Flexible circuit board and preparation method thereof, flexible circuit board assembly and display device

Abstract

A flexible circuit board includes a first protective layer, a plurality of conductive layers, and a second protective layer. The plurality of conductive layers are arranged on the first protective layer and are sequentially stacked in the direction perpendicular to the first protective layer. And the second protection layer is arranged on one side, far away from the first protection layer, of the plurality of conductive layers. Wherein the conductive layer, closest to the second protection layer, in the plurality of conductive layers is a first conductive layer, and the first conductive layer comprises a plurality of bonding pads; the second protection layer is provided with a plurality of first openings, and the plurality of first openings respectively expose a part of the plurality of bonding pads; and the area of the orthographic projection of each first opening on the first protection layer is smaller than the surface area of the bonding pad.

Description

Technical Field

[0001] The present disclosure relates to the field of display technologies, and in particular, to a flexible circuit board, a method for manufacturing the same, a flexible circuit board assembly, and a display device. Background Art

[0002] Flexible Printed Circuit (FPC) has characteristics such as high wiring density, light weight, thin thickness, and bendability, and is currently widely used in many display devices such as mobile phones, laptop computers, wearable devices, and tablet computers. Summary of the Invention

[0003] On the one hand, a flexible circuit board is provided. The flexible circuit board includes a first protective layer, a plurality of conductive layers, and a second protective layer. The plurality of conductive layers are disposed on the first protective layer and are sequentially stacked in a direction perpendicular to the first protective layer. The second protective layer is disposed on a side of the plurality of conductive layers away from the first protective layer. Wherein, the conductive layer closest to the second protective layer among the plurality of conductive layers is a first conductive layer, and the first conductive layer includes a plurality of pads; the second protective layer has a plurality of first openings, and the plurality of first openings respectively expose a part of the plurality of pads; the area of the orthographic projection of each first opening on the first protective layer is smaller than the surface area of the pad.

[0004] In some embodiments, at least one groove is formed on a surface of the pad on the exposed side.

[0005] In some embodiments, the groove penetrates through the pad.

[0006] In some embodiments, the bottom wall of the groove is located within the pad.

[0007] In some embodiments, the side wall of the groove is flush with the edge of the first opening.

[0008] In some embodiments, the orthographic projection of the end of the first opening away from the first protective layer on the first protective layer is located within the orthographic projection of the end of the first opening close to the first protective layer on the first protective layer.

[0009] In some embodiments, the pad includes a sub - part and at least one branch - part; the sub - part includes a first node and a second node arranged at intervals, the branch - part includes opposite first and second ends, the first end is connected to the first node, and the second end is connected to the second node.

[0010] In some embodiments, the pad includes a plurality of branch - parts located on both sides of the sub - part, and the plurality of branch - parts are symmetrically arranged with respect to the sub - part.

[0011] In some embodiments, the conductive layer second closest to the second protective layer among the plurality of conductive layers is the second conductive layer; the second conductive layer includes a plurality of pad auxiliary portions; the flexible circuit board further includes: an insulating layer disposed between the first conductive layer and the second conductive layer, and a plurality of vias are provided in the insulating layer; the pads are connected to the pad auxiliary portions through the vias.

[0012] In some embodiments, the orthographic projection of the pad on the first protective layer and the orthographic projection of the pad auxiliary portion on the first protective layer at least partially overlap.

[0013] On the other hand, a method for manufacturing a flexible circuit board is provided. The manufacturing method includes: providing a copper-clad substrate, the copper-clad substrate including a plurality of conductive layers stacked in sequence, and one conductive layer located at the top layer among the plurality of conductive layers is the first conductive layer; forming a plurality of pads in the first conductive layer; forming a second protective layer on a side of the first conductive layer away from other conductive layers; the second protective layer has a plurality of first openings, and a part of each of the plurality of pads is exposed by the plurality of first openings; the area of the orthographic projection of each first opening on the first protective layer is smaller than the surface area of the pad; forming a first protective layer on a side of the plurality of conductive layers away from the second protective layer.

[0014] In some embodiments, the conductive layer second closest to the second protective layer among the plurality of conductive layers is the second conductive layer; the copper-clad substrate further includes: an insulating layer disposed between the first conductive layer and the second conductive layer; before forming the first protective layer on a side of the plurality of conductive layers away from the second protective layer, the manufacturing method further includes: forming a plurality of vias in the insulating layer; forming a plurality of pad auxiliary portions in the second conductive layer, and the pads are connected to the pad auxiliary portions through the vias.

[0015] In yet another aspect, a flexible circuit board assembly is provided, including: a flexible circuit board, the flexible circuit board being the flexible circuit board as described in any of the above embodiments; an optical component, the optical component including a plurality of pins; a bonding portion located in each of the first openings of the flexible circuit board; the pins are bonded to the pads of the flexible circuit board through the bonding portion.

[0016] In yet another aspect, a display device is provided. The display device includes: the flexible circuit board assembly as described in any of the above embodiments. Description of the Drawings

[0017] To more clearly illustrate the technical solutions in the present disclosure, the following will briefly introduce the drawings required for use in some embodiments of the present disclosure. Obviously, the drawings in the following description are only the drawings of some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings. In addition, the drawings in the following description can be regarded as schematic diagrams and are not limitations on the actual sizes of the products involved in the embodiments of the present disclosure, the actual processes of the methods, etc.

[0018] Figure 1 Structural diagram of a display device according to some embodiments;

[0019] Figure 2 Structural diagram of a flexible circuit board assembly according to some embodiments;

[0020] Figure 3A Structural diagram of another flexible circuit board assembly according to some embodiments;

[0021] Figure 3B Top view of another flexible circuit board assembly according to some embodiments;

[0022] Figure 4A Structural diagram of a flexible circuit board according to some embodiments;

[0023] Figure 4B Partial top view of a flexible circuit board according to some embodiments;

[0024] Figure 5 Structural diagram of another flexible circuit board assembly according to some embodiments;

[0025] Figure 6 Structural diagram of another flexible circuit board according to some embodiments;

[0026] Figure 7A Structural diagram of another flexible circuit board assembly according to some embodiments;

[0027] Figure 7B Top view of another flexible circuit board assembly according to some embodiments;

[0028] Figure 8 Structural diagram of another flexible circuit board according to some embodiments;

[0029] Figure 9 Structural diagram of another flexible circuit board assembly according to some embodiments;

[0030] Figure 10 Structural diagram of another flexible circuit board according to some embodiments;

[0031] Figure 11Structural diagram of another flexible circuit board according to some embodiments;

[0032] Figure 12 Flowchart of a method for manufacturing a flexible circuit board according to some embodiments;

[0033] Figures 13A to 13D Structural diagrams corresponding to the respective steps in a method for manufacturing a flexible circuit board according to some embodiments. Detailed implementation manners

[0034] Next, the technical solutions in some embodiments of the present disclosure will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present disclosure.

[0035] Unless otherwise required by the context, throughout the specification and claims, the term "comprise" and its other forms, such as the third-person singular form "comprises" and the present participle form "comprising", are interpreted as open and inclusive, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific example" or "some examples", etc., are intended to indicate that the specific features, structures, materials or characteristics related to the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representations of the above terms do not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials or characteristics may be included in any one or more embodiments or examples in any appropriate manner.

[0036] Hereinafter, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present disclosure, unless otherwise stated, the meaning of "a plurality" is two or more.

[0037] In describing some embodiments, the expressions "coupled" and "connected" and their derivatives may be used. The term "connected" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral one; it can be directly connected or indirectly connected through an intermediate medium. The term "coupled" indicates, for example, that two or more components have direct physical contact or electrical contact. The term "coupled" or "communicatively coupled" may also mean that two or more components do not have direct contact with each other, but still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited to the content herein.

[0038] "At least one of A, B, and C" has the same meaning as "at least one of A, B, or C", and both include the following combinations of A, B, and C: only A, only B, only C, the combination of A and B, the combination of A and C, the combination of B and C, and the combination of A, B, and C.

[0039] "A and / or B" includes the following three combinations: only A, only B, and the combination of A and B.

[0040] In addition, the use of "based on" means open and inclusive, because a process, step, calculation, or other action "based on" one or more of the stated conditions or values can in practice be based on additional conditions or values beyond the stated ones.

[0041] It should be understood that when a layer or element is referred to as being on another layer or substrate, it can be that the layer or element is directly on the other layer or substrate, or there can be an intermediate layer between the layer or element and the other layer or substrate.

[0042] Exemplary embodiments are described herein with reference to cross-sectional views and / or plan views that are idealized exemplary drawings. In the drawings, the thickness of the layers and the area of the regions are enlarged for clarity. Therefore, variations in the shape relative to the drawings due to, for example, manufacturing techniques and / or tolerances can be envisioned. Accordingly, the exemplary embodiments should not be construed as being limited to the shapes of the regions shown herein, but rather include shape deviations caused by, for example, manufacturing. For example, an etched region shown as rectangular will generally have curved features. Thus, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shape of the regions of the device and are not intended to limit the scope of the exemplary embodiments.

[0043] Some embodiments of the present disclosure provide a display device, which can be any display device that displays images whether in motion (e.g., video) or stationary (e.g., still images), and whether text or not. More specifically, it is expected that the display device of the embodiments can be implemented in or associated with a variety of electronic devices, such as (but not limited to) mobile phones, wireless devices, personal digital assistants (PDAs), handheld or portable computers, GPS receivers / navigators, cameras, MP4 video players, video cameras, game consoles, watches, clocks, calculators, television monitors, flat panel displays, computer monitors, automotive displays (e.g., odometer displays, etc.), navigators, cockpit controllers and / or displays, displays of camera views (e.g., displays of rearview cameras in vehicles), electronic photos, electronic billboards or signs, projectors, architectural structures, packaging, and aesthetic structures (e.g., displays of images of a piece of jewelry), etc.

[0044] In an embodiment of the present disclosure, taking the display device as a wearable device as an example for illustration, the device can be a smart watch, a smart bracelet, etc.

[0045] Figure 1 FIG. is a structural diagram of a display device according to some embodiments. As Figure 1 shown, the display device 1000 includes a frame 100, a cover plate 200, a display panel 300, a flexible circuit board assembly 400, and other electronic accessories, etc.

[0046] As Figure 1 shown, the longitudinal cross-section of the frame 100 is U-shaped, the display panel 300, the flexible circuit board assembly 400, and other electronic accessories are disposed within the frame 100, the flexible circuit board assembly 400 is located between the display panel 300 and the frame 100, and the cover plate 200 is located on the side of the display panel 300 away from the flexible circuit board assembly 400.

[0047] Exemplarily, the flexible circuit board assembly 400 is located on the non-light-emitting side of the display panel 300, and the flexible circuit board assembly 400 is coupled to the display panel 300. The flexible circuit board assembly 400 is used to provide a driving signal for the display panel 300, thereby ensuring the normal display of the display panel 300. Among them, the side of the display panel 300 for displaying the picture is the light-emitting side, and the non-light-emitting side of the display panel 300 is the side opposite to the light-emitting side in the display panel 300.

[0048] Exemplarily, the above display panel 300 may be: an Organic Light Emitting Diodes (OLED) display panel, a Quantum Dot Light Emitting Diodes (QLED) display panel, a Micro Light Emitting Diodes (Micro LED) display panel, etc. The present disclosure does not make specific limitations thereto.

[0049] In addition, the display panel 300 may be a flexible display panel. When the display panel 300 is a flexible display panel, the display device 1000 is a flexible display device.

[0050] In some examples, in combination with Figure 2 and Figure 3A , the flexible circuit board assembly 400 includes a flexible circuit board 10, an optical component 20, and a bonding portion 30. The optical component 20 is bonded to the flexible circuit board 10 through the bonding portion 30.

[0051] Exemplarily, the optical component 20 may be an infrared sensor or an Ambient Light Sensor (ALS device), etc.

[0052] For example, when the display device 1000 is a smart watch, the optical component 20 may be an ALS device. The ALS device is used to detect the light intensity in the usage scenario of the smart watch. The smart watch adjusts the screen brightness of the display screen according to the ambient light intensity detected by the ALS device to ensure that the user can clearly view the screen information.

[0053] Exemplarily, the bonding portion 30 is formed of solder. Among them, the material of the solder is a conductive material, so that the optical component 20 and the flexible circuit board 10 can be fixedly connected and electrically connected through the bonding portion 30 at the same time.

[0054] Exemplarily, the solder may include tin-lead solder, binary alloy lead-free solder, or multi-alloy lead-free solder, etc. Specifically, the material of the solder may include tin-lead alloy (Sn-Pb), tin-silver alloy (Sn-Ag), tin-copper alloy (Sn-Cu), and may also be at least one of tin-silver-copper alloy (Sn-Ag-Cu), tin-zinc-bismuth alloy (Sn-Zn-Bi), tin-silver-bismuth-copper alloy (Sn-Ag-Bi-Cu), tin-silver-bismuth-indium alloy (Sn-Ag-Bi-In), tin-silver-bismuth-copper-germanium alloy (Sn-Ag-Bi-Cu-Ge).

[0055] In some examples, such as Figure 2As shown, the flexible circuit board assembly 400 further includes a connection portion 40 located on the flexible circuit board 10. The connection portion 40 is electrically connected to the display panel 300 or other circuit boards through a Board-To-Board (BTB) connection method.

[0056] Exemplarily, as Figure 3A shown, the flexible circuit board 10 includes: a first protective layer 1, a plurality of conductive layers 2, and a second protective layer 3. The plurality of conductive layers 2 are disposed on the first protective layer 1 and are stacked in sequence in a direction perpendicular to the first protective layer 1. The second protective layer 3 is disposed on a side of the plurality of conductive layers 2 away from the first protective layer 1.

[0057] Among them, both the first protective layer 1 and the second protective layer 3 can effectively protect the plurality of conductive layers 2.

[0058] Exemplarily, the first protective layer 1 can be a single-layer structure, a double-layer structure, or a multi-layer structure. For example, the first protective layer 1 is a single-layer structure composed of a Polyimide (PI) layer. Another example is that the first protective layer 1 is a double-layer structure composed of a glue layer and a PI layer stacked in sequence. The embodiments of the present disclosure do not limit this.

[0059] The structure of the second protective layer 3 can be the same as or different from the structure of the first protective layer 1. For example, the structure of the second protective layer 3 is the same as the structure of the first protective layer 1. Both the second protective layer 3 and the first protective layer 1 are single-layer structures composed of PI layers.

[0060] Exemplarily, the material of each conductive layer 2 can include a metal material, such as copper Cu, or other suitable materials. When the material of the conductive layer 2 includes copper, the conductive layer 2 can be a copper foil.

[0061] Exemplarily, the number of conductive layers 2 can be two layers, three layers, or more layers, etc. The embodiments of the present disclosure do not limit this.

[0062] It should be noted that an insulating layer is provided between two adjacent conductive layers 2, and the insulating layer between adjacent conductive layers 2 is used to electrically insulate the two adjacent conductive layers 2.

[0063] As Figure 3A shown, among the plurality of conductive layers 2, the conductive layer 2 closest to the second protective layer 3 is the first conductive layer 21, and the first conductive layer 21 includes a plurality of pads 211.

[0064] Exemplarily, as Figure 3A shown, the second protective layer 3 has a plurality of first openings 31, and the plurality of first openings 31 respectively expose a part of the plurality of pads 211.

[0065] Exemplarily, the first openings 31 correspond to the pads 211 one by one. For example, one first opening 31 is used to expose a part of one pad 211.

[0066] It can be understood that some of the multiple pads 211 are used to connect to the optical component 20; some of the multiple pads 211 can also be connected to other devices. Among them, other devices can be, for example, resistors for controlling current, dividing voltage, and matching impedance, capacitors for storing charge and releasing energy, inductors for storing magnetic energy and resisting current changes, integrated circuits in which multiple electronic components are integrated together, etc., but are not limited thereto.

[0067] Exemplarily, as Figure 3A shown, the optical component 20 has pins 201, and the exposed part of the pad 211 is connected to the pin 201 of the optical component 20 through the bonding portion 30, so as to realize the electrical connection between the optical component 20 and the flexible circuit board 10.

[0068] Specifically, the electrical connection between the optical component 20 and the flexible circuit board 10 can be realized through Surface Mounted Technology (SMT for short).

[0069] Surface Mounted Technology refers to: mounting leadless or short-lead surface-mounted components on the surface of a circuit board or other substrates, and connecting and assembling the circuits by methods such as reflow soldering or dip soldering. Specifically in the embodiments of the present disclosure, the optical component 20 is mounted on the surface of the flexible circuit board 10 and is connected and assembled by methods such as reflow soldering or dip soldering, so as to realize the electrical connection between the optical component 20 and the flexible circuit board 10.

[0070] Specifically, when realizing the electrical connection between the optical component 20 and the flexible circuit board 10, first print solder for reflow soldering on the multiple pins 201 of the optical component 20 or the corresponding pads 211 on the flexible circuit board 10, align and contact the multiple pins 201 of the optical component 20 with the pads 211 of the flexible circuit board 10, heat the solder by soldering techniques such as reflow soldering or dip soldering to make the solder molten, and then quickly cool and lower the temperature to make the solder solidify, forming the bonding portion 30. The bonding portion 30 is located within the first opening 31. The surface of the bonding portion 30 close to the pad 211 is electrically connected to the pad 211 of the flexible circuit board 10, and the surface of the bonding portion 30 close to the pin 201 is electrically connected to the pin 201. Thus, the electrical connection between the optical component 20 and the flexible circuit board 10 is realized through the bonding portion 30.

[0071] Exemplarily, the number of pads 211 connected to one optical component 20 can be one, two or more, etc., and the embodiments of the present disclosure do not limit this.

[0072] Exemplarily, as Figure 3A shown, when the number of pins 201 of the optical component 20 is multiple, the number of pads 211 connected to one optical component 20 is also multiple, and one pad 211 is connected to one pin 201 of the optical component 20.

[0073] Among them, multiple pads 211 connected to the same optical component 20 can transmit the same signal or different signals.

[0074] For example, multiple pads 211 connected to the same optical component 20 are used to transmit different signals. Specifically, multiple pads 211 connected to one optical component 20 are connected to multiple traces provided on the conductive layer 2 for transmitting different signals. When the optical component 20 is connected to the flexible circuit board 10, multiple pads 211 can respectively transmit different signals from multiple traces to corresponding multiple pins 201 on the optical component 20.

[0075] In some examples, in combination with Figure 3A and Figure 3B , the portion of the pad 211 exposed by the first opening 31 contacts the bonding portion 30.

[0076] It can be understood that the portion of the pad 211 exposed by the first opening 31 is adapted to the shape of the first opening 31. For example, the orthographic projection of the first opening 31 on the first protective layer 1 is circular, and the orthographic projection of the portion of the pad 211 exposed by the first opening 31 on the first protective layer 1 is also circular. Another example is that the orthographic projection of the first opening 31 on the first protective layer 1 is rectangular, and the orthographic projection of the portion of the pad 211 exposed by the first opening 31 on the first protective layer 1 is also rectangular. Figure 3B shows the case where the orthographic projection of the portion of the pad 211 exposed by the first opening 31 on the first protective layer 1 is rectangular. At this time, the pad 211 can be called a rectangular pad.

[0077] In the thickness direction of the flexible circuit board 10, when the cross-sectional area at different positions of the first opening 31 remains unchanged, the orthographic projection of the portion of the pad 211 exposed by the first opening 31 on the first protective layer 1 coincides with the orthographic projection of the cross-section at any position of the first opening 31 on the first protective layer 1. That is, the area of the portion of the pad 211 exposed by the first opening 31 is equal to the cross-sectional area at any position of the first opening 31 (that is, the area of the orthographic projection of the first opening 31 on the first protective layer 1).

[0078] In some implementations, there is an easy problem of poor soldering between the optical component 20 and the flexible circuit board 10. When the soldering between the optical component 20 and the flexible circuit board 10 is not firm, during the overall assembly of the display device 1000 including the flexible circuit board assembly 400 or during transportation, due to vibration and collision, the optical component 20 and the flexible circuit board 10 may become detached, affecting the connectivity between the optical component 20 and the flexible circuit board 10 and the functional use of the optical component 20.

[0079] Based on this, the present disclosure makes improvements to the flexible circuit board 10. For example, Figures 4A to 6 as shown, in the flexible circuit board 10 provided in the embodiments of the present disclosure, the area of the orthographic projection of each first opening 31 on the first protective layer 1 is smaller than the surface area of the solder pad 211.

[0080] In some examples, in combination with Figure 4A and Figure 4B , the orthographic projection of the first opening 31 on the first protective layer 1 completely falls within the orthographic projection of the solder pad 211 on the first protective layer 1.

[0081] It should be noted that the above "surface area of the solder pad 211" refers to: the sum of the surface areas of the outer surfaces of the solder pad 211 exposed by the first opening 31. Among them, the outer surface refers to the surface exposed outside. Specifically, in the embodiments of the present disclosure, the surface area of the solder pad 211 refers to the sum of the areas of the surfaces of the solder pad 211 exposed outside by the first opening 31.

[0082] Exemplarily, the number of outer surfaces of the solder pad 211 exposed by the first opening 31 can be one or more. The embodiments of the present disclosure do not limit this.

[0083] For example, as Figure 4A and Figure 6 shown, the portion of the solder pad 211 exposed by the first opening 31 includes multiple outer surfaces.

[0084] At this time, the surface area of the solder pad 211 is equal to the sum of the areas of the multiple outer surfaces of the solder pad 211 exposed by the first opening 31.

[0085] It can be understood that when the portion of the solder pad 211 exposed by the first opening 31 includes multiple side surfaces, the bonding portion 30 contacts all the side surfaces. At this time, the contact area between the bonding portion 30 and the solder pad 211 is the surface area of the solder pad 211 exposed by the first opening 31. The larger the contact area between the bonding portion 30 and the solder pad 211, the firmer the soldering between the optical component 20 and the flexible circuit board 10.

[0086] In such as Figure 3AIn the illustrated embodiment, in the thickness direction of the flexible circuit board 10, the cross-sectional area at different positions of the first opening 31 remains unchanged, and the surface area of the exposed portion of the pad 211 is equal to the cross-sectional area of the first opening 31 (i.e., the area of the orthographic projection of the first opening 31 on the first protective layer 1). At this time, the contact area between the bonding portion 30 and the pad 211 is equal to the surface area of the exposed portion of the pad 211 by the first opening 31, that is, the cross-sectional area of the first opening 31.

[0087] In this embodiment of the present disclosure, by making the surface area of the pad 211 exposed by the first opening 31 larger than the area of the orthographic projection of the first opening 31 on the first protective layer 1, that is, making the contact area between the pad 211 and the bonding portion 30 larger, the welding strength between the optical component 20 and the flexible circuit board 10 is enhanced, so that the welding between the optical component 20 and the flexible circuit board 10 is more firm, the welding quality between the optical component 20 and the flexible circuit board 10 is improved, and the probability of fracture at the welding joint between the optical component 20 and the flexible circuit board 10 due to the insecure welding between the optical component 20 and the flexible circuit board 10 during transportation collisions or vibrations is reduced, ensuring the effectiveness of the electrical connection between the optical component 20 and the flexible circuit board 10.

[0088] In some embodiments, as Figures 4A to 6 shown, at least one groove A is formed on the exposed side surface of the pad 211.

[0089] Exemplarily, the number of grooves A can be one, two or more. The embodiments of the present disclosure do not limit this. For example, as Figure 4A and Figure 6 shown, one groove A is formed on the exposed side surface of the pad 211.

[0090] Exemplarily, the orthographic projection of the groove A on the first protective layer 1 can be any one of a zigzag shape, a cross shape or a polygon; wherein, the polygon can be any one of a triangle, a pentagon, a hexagon, etc. Of course, the projection of the groove A on the first protective layer 1 can also be any other shape. The embodiments of the present disclosure do not limit this.

[0091] Exemplarily, when at least one groove A is formed on the exposed side surface of the pad 211, the bonding portion 30 includes at least one protruding portion that extends into the groove A.

[0092] It is understandable that the protruding part of the bonding portion 30 and the groove A of the pad 211 match each other. Specifically, it may include: matching in shape, matching in quantity, and matching in positional relationship. Among them, the number of the protruding parts of the bonding portion 30 is the same as the number of the grooves A of the pad, and the protruding parts of the bonding portion 30 and the grooves A of the pad correspond one by one. That is, one protruding part of the bonding portion 30 is located in one groove A of the pad.

[0093] Optionally, when the number of the grooves A of the pad 211 is one, the number of the protruding parts of the bonding portion 30 is also one; when the number of the grooves A of the pad 211 is two, the number of the protruding parts of the bonding portion 30 is also two. Among them, Figure 6 it is shown that a groove A is formed on the exposed side surface of the pad 211. At this time, combined with Figure 6 and Figure 7A , the bonding portion 30 includes one protruding part, and this protruding part extends into the groove A. At this time, in the cross-sectional view of the flexible circuit board assembly 400, the shape of the bonding portion 30 is "T" shaped.

[0094] Exemplarily, the protruding part of the bonding portion 30 extends into the groove A of the pad 211 and is in close contact with the bottom wall and the side wall of the groove A.

[0095] With the above settings, by forming the groove A on the exposed side surface of the pad 211, the surface area of the pad 211 exposed by the first opening 31 is increased, and the contact area between the bonding portion 30 and the pad 211 is increased, thereby improving the welding quality between the optical component 20 and the flexible circuit board 10; at the same time, the regional space for accommodating the bonding portion 30 is increased. When the bonding portion 30 is formed by welding technologies such as reflow soldering or dip soldering, the bonding portion 30 can also be filled in the groove A of the pad 211, so as to further improve the stability and firmness of the welding between the optical component 20 and the flexible circuit board 10, effectively improving the problem of poor welding between the optical component 20 and the flexible circuit board 10, and ensuring the effectiveness of the electrical connection between the optical component 20 and the flexible circuit board 10; at the same time, it can also improve the abnormal transmission phenomenon between the optical component 20 and the flexible circuit board 10 caused by the fracture of the welding part between the optical component 20 and the flexible circuit board 10 due to collision during transportation.

[0096] It should be noted that the specific setting method of the groove A includes various types and can be selected according to actual needs.

[0097] In one implementation, as Figure 4A shown, the bottom wall aa of the groove A is located within the pad 211. That is, the groove A only penetrates a part of the pad 211. At this time, both the bottom wall aa and the side wall bb of the groove A are located within the pad 211.

[0098] Combined withFigure 4A and Figure 5 As shown in Figure 5 , the bonding portion 30 contacts the bottom wall aa and the side wall bb of the groove A. Thereby, the contact area between the solder and the pad 211 is increased, ensuring the welding quality between the optical component 20 and the flexible circuit board 10 and improving the product yield. Moreover, both the bottom wall aa and the side wall bb of the groove A are located within the pad 211, that is, the contact area between the bonding portion 30 and the pad 211 is large, ensuring good connectivity between the bonding portion 30 and the pad 211, and thus ensuring the effectiveness of the electrical connection between the optical component 20 and the flexible circuit board 10.

[0099] Furthermore, as Figure 4A shown, when the bottom wall aa of the groove A is located within the pad 211, the side wall bb of the groove A is flush with the edge of the first opening 31.

[0100] Exemplarily, as Figure 4A shown, the orthographic projection of the groove A on the first protective layer 1 coincides with the orthographic projection of the first opening 31 on the first protective layer 1.

[0101] In this case, as Figure 5 shown, a part of the bonding portion 30 is located within the groove A, and the orthographic projection of the bonding portion 30 on the first protective layer 1 coincides with the orthographic projection of the groove A on the first protective layer 1.

[0102] In this embodiment, by making the side wall bb of the groove A flush with the edge of the first opening 31, the space in the groove A for accommodating the bonding portion 30 can be increased to a large extent, so that the material of the bonding portion 30 increases, which is beneficial to further improving the welding quality between the optical component 20 and the flexible circuit board 10 and ensuring the stability of signal transmission between the optical component 20 and the flexible circuit board 10.

[0103] Furthermore, in combination with Figure 4A and Figure 5 , the bottom wall aa of the groove A fits the surface of the bonding portion 30 close to the first protective layer 1. Since the bottom wall aa of the groove A is a flat surface, when the bonding portion 30 is formed by welding techniques such as reflow soldering or dip soldering, the bonding portion 30 and the pad 211 can be tightly combined, further ensuring the welding quality between the optical component 20 and the flexible circuit board 10, and reducing the probability that the optical component 20 and the flexible circuit board 10 break at the welding point under the condition of collision or vibration during transportation or other environments (for example, when the flexible circuit board 10 is bent), greatly improving the product yield.

[0104] In another implementation, as Figure 6 shown, the groove A penetrates through the pad 211.

[0105] Exemplarily, as Figure 6 shown, the orthographic projection of the groove A on the first protective layer 1 is within the range of the orthographic projection of the first opening 31 on the first protective layer 1.

[0106] Exemplarily, as Figure 6 shown, the bottom wall aa of the groove A is located within the insulating layer close to the first conductive layer 21.

[0107] Exemplarily, in combination with Figures 6 to 7B , when the groove A penetrates the pad 211 and the number of the grooves A is one, the shape of the orthographic projection of the pad 211 on the first protective layer 1 is annular. At this time, the pad 211 is different from the above-mentioned conventional rectangular pad and can be called a special-shaped pad 211.

[0108] In this case, a part of the bonding portion 30 is located within the groove A and contacts the bottom wall aa and the side wall bb of the groove A, increasing the contact area between the bonding portion 30 and the pad 211, so as to improve the welding quality between the optical component 20 and the flexible circuit board 10; moreover, the groove A penetrates the pad 211, further increasing the space in the groove A for accommodating the bonding portion 30, increasing the material of the bonding portion 30, thereby further ensuring the welding quality between the optical component 20 and the flexible circuit board 10 and ensuring the stability of signal transmission between the optical component 20 and the flexible circuit board 10.

[0109] In some embodiments, as Figure 8 and Figure 9 shown, the orthographic projection of the end of the first opening 31 far from the first protective layer 1 on the first protective layer 1 is within the range of the orthographic projection of the end of the first opening 31 close to the first protective layer 1 on the first protective layer 1. That is, the cross-sectional area of the end of the first opening 31 far from the first protective layer 1 is smaller than the cross-sectional area of the end of the first opening 31 close to the first protective layer 1.

[0110] Exemplarily, in the cross-sectional view of the flexible circuit board 10, the shape of the first opening 31 is trapezoidal.

[0111] Wherein, the end of the first opening 31 close to the first protective layer 1 may expose all the surfaces of the pad 211 close to the second protective layer 3; or may expose a part of the surface of the pad 211 close to the second protective layer 3, and the embodiments of the present disclosure do not limit this.

[0112] In this example, as Figure 9 shown, the bonding portion 30 is filled in the first opening 31. The side wall of the pin 201 of the optical component 20 contacts the end of the first opening 31 far from the first protective layer 1, or there is a small distance therebetween. At this time, the bonding portion 30 contacts the bottom surface and part of the side surface of the pin 201 of the optical component 20.

[0113] With the above settings, when forming the bonding portion 30 by soldering techniques such as reflow soldering or dip soldering, since the cross-sectional area of the first opening 31 at the end far from the first protective layer 1 is smaller than the cross-sectional area of the first opening 31 at the end close to the first protective layer 1, when the pin 201 of the optical component 20 extends into the first opening 31, the side surface of the pin 201 does not fit with the first opening 31. Therefore, after the solder used to form the bonding portion 30 liquefies, the liquid solder can climb along the bottom surface of the pin 201 of the optical component 20 close to the pad 211 to both sides of the pin 201, that is, the solder is not only located on the bottom surface of the pin 201 of the optical component 20 close to the pad 211, but also on both sides of the pin 201 of the optical component 20, further increasing the contact area between the pin 201 of the optical component 20 and the bonding portion 30, thereby improving the soldering quality between the optical component 20 and the flexible circuit board 10, effectively avoiding the disconnection between the optical component 20 and the flexible circuit board 10 at the soldering position, and increasing the stability between the optical component 20 and the flexible circuit board 10; moreover, by changing the sizes of both ends of the first opening 31, a stable connection between the optical component 20 and the flexible circuit board 10 is achieved, with a simple process, strong operation feasibility, relatively low processing cost, and can be mass-produced and used.

[0114] In some embodiments, as Figure 10 shown, the pad 211 includes a sub-portion 211a and at least one branch portion 211b.

[0115] Among them, as Figure 10 shown, the sub-portion 211a includes a first node a1 and a second node a2 arranged at intervals, the branch portion 211b includes opposite first end b1 and second end b2, the first end b1 is connected to the first node a1, and the second end b2 is connected to the second node a2. That is, the sub-portion 211a and at least one branch portion 211b are connected in parallel.

[0116] Exemplarily, the number of branch portions 211b in the pad 211 can be one, two or more. The embodiments of the present disclosure do not limit this.

[0117] It can be understood that the portion of the pad 211 exposed by the first opening 31 is connected to the pin 201 of the optical component 20, and the end of the pad 211 far from the second protective layer 3 is connected to the trace on the flexible circuit board 10, thereby realizing the electrical connection between the optical component 20 and the flexible circuit board 10.

[0118] When the pad 211 includes a sub - portion 211a and at least one branch - portion 211b, the pin 201 of the optical component 20 can be connected to the trace on the flexible circuit board 10 through the sub - portion 211a, and the pin 201 of the optical component 20 can also be connected to the trace on the flexible circuit board 10 through the branch - portion 211b. When there is a poor soldering between the optical component 20 and one of the sub - portion 211a and at least one branch - portion 211b, the optical component 20 can still be connected to the trace on the flexible circuit board 10 through the other of the sub - portion 211a and at least one branch - portion 211b. Thus, the probability of poor communication between the optical component 20 and the flexible circuit board 10 is reduced, ensuring the effectiveness of the electrical connection between the optical component 20 and the flexible circuit board 10.

[0119] As can be seen from the above, the part of the pad 211 exposed by the first opening 31 is electrically connected to the optical component 20 through the bonding portion 30. As Figure 10 shown, both the sub - portion 211a and the branch - portion 211b of the pad 211 can be electrically connected to the optical component 20. At this time, the first opening 31 can simultaneously expose the sub - portion 211a and the branch - portion 211b of the pad 211. It can be understood that the first opening 31 also exposes the gap position between the sub - portion 211a and the branch - portion 211b, and the bonding portion 30 can also fill this gap position, so that the material of the bonding portion 30 increases, thereby increasing the soldering strength between the optical component 20 and the flexible circuit board 10, further ensuring the soldering quality between the optical component 20 and the flexible circuit board 10, and ensuring the stability of signal transmission between the optical component 20 and the flexible circuit board 10.

[0120] Furthermore, when electrical connection can be achieved between the optical component 20 and the flexible circuit board 10 through the sub - portion 211a or any one of the branch - portions 211b, when forming the bonding portion 30 by soldering techniques such as reflow soldering or dip soldering, the soldering angle between the optical component 20 and the flexible circuit board 10 and the amount of the bonding portion 30 required can be freely selected, further improving the soldering effect between the optical component 20 and the flexible circuit board 10.

[0121] In some embodiments, the pins of some optical components 20 (for example, ALS devices) are small. When the optical component 20 is mounted on the surface of the flexible circuit board 10 by the SMT process, it is difficult to accurately align the pins of the ALS device with the pads 211 of the flexible circuit board 10. When there is a slight misalignment between the pins of the ALS device and the pads of the flexible circuit board 10, it will cause problems such as poor soldering (for example, loose soldering) between the ALS device and the flexible circuit board 10, resulting in abnormal signal transmission between the ALS device and the flexible circuit board 10 and affecting the product yield.

[0122] In the above embodiments of the present application, the pad 211 includes a sub - portion 211a and at least one branch portion 211b, and the first opening 31 exposes both the sub - portion 211a and the branch portion 211b of the pad 211. The area of the projection of the exposed part of the pad 211 by the first opening 31 on the plane where the first protective layer 1 is located is increased, reducing the difficulty of aligning the pins of the ALS device with the pad 211 of the flexible circuit board 10, reducing the probability of poor soldering between the ALS device and the flexible circuit board 10, and ensuring the effectiveness of the electrical connection between the optical component 20 and the flexible circuit board 10.

[0123] In some embodiments, as Figure 10 shown, the pad 211 includes a plurality of branch portions 211b located on both sides of the sub - portion 211a, and the plurality of branch portions 211b are symmetrically arranged with respect to the sub - portion 211a.

[0124] Exemplarily, the number of the branch portions 211b included in the pad 211 is an even number, and the even - numbered branch portions 211b are evenly distributed on both sides of the sub - portion 211a. For example, the number of the branch portions 211b included in the pad 211 can be two, four, six, eight, etc. Figure 10 Two branch portions 211b are shown, and the two branch portions 211b are respectively located on both sides of the sub - portion 211a.

[0125] In this embodiment, the plurality of branch portions 211b are independent of each other and can all achieve the electrical connection between the optical component 20 and the flexible circuit board 10, improving the effectiveness of the electrical connection between the optical component 20 and the flexible circuit board 10; moreover, the plurality of branch portions 211b are symmetrically arranged with respect to the sub - portion 211a. When forming the bonding portion 30 by soldering techniques such as reflow soldering or dip soldering, the forces at different positions of the pad 211 are uniform, ensuring the stability of soldering and the soldering quality between the optical component 20 and the flexible circuit board 10.

[0126] In some embodiments, as Figure 11 shown, the second - closest conductive layer 2 to the second protective layer 3 among the plurality of conductive layers 2 is the second conductive layer 22; the second conductive layer 22 includes a plurality of pad auxiliary portions 221; the flexible circuit board 10 further includes: an insulating layer 4 disposed between the first conductive layer 21 and the second conductive layer 22, and a plurality of vias 41 are disposed in the insulating layer 4; the pad 211 is connected to the pad auxiliary portion 221 through the vias 41.

[0127] Exemplarily, the insulating layer 4 can be made of at least one of polyimide (PI for short), polydimethylsiloxane (PDM for short), liquid crystal polymer (LCP for short), modified polyimide (MPI for short), platinum-catalyzed silica gel (ecoflex), and hydrogel.

[0128] Exemplarily, a conductive material can be filled in the via 41 through electroplating or other processes, so that the pad 211 and the pad auxiliary part 221 are electrically connected. At this time, the pad 211 and the pad auxiliary part 221 constitute a "dual-pad" design.

[0129] Exemplarily, one end of the pad 211 close to the first protective layer 1 is connected to the wire in the flexible circuit board 10 through the pad auxiliary part 221. The signal in the flexible circuit board 10 is transmitted to the pin of the optical component 20 through the pad 211 and the pad auxiliary part 221, ensuring the functional use of the optical component 20.

[0130] In this embodiment, by providing the pad auxiliary part 221, the pad 211 and the pad auxiliary part 221 located in different conductive layers 2 constitute a "dual-pad" design, improving the connection strength between the flexible circuit board 10 and the optical component 20 and ensuring the stability of the connection between the flexible circuit board 10 and the optical component 20.

[0131] In some embodiments, as Figure 11 shown, the orthographic projection of the pad 211 on the first protective layer 1 and the orthographic projection of the pad auxiliary part 221 on the first protective layer 1 at least partially overlap.

[0132] It should be noted that the above "the orthographic projection of the pad 211 on the first protective layer 1 and the orthographic projection of the pad auxiliary part 221 on the first protective layer 1 at least partially overlap" includes two cases: the orthographic projection of the pad 211 on the first protective layer 1 and the orthographic projection of the pad auxiliary part 221 on the first protective layer 1 partially overlap, and the orthographic projection of the pad 211 on the first protective layer 1 and the orthographic projection of the pad auxiliary part 221 on the first protective layer 1 completely overlap.

[0133] Exemplarily, as Figure 11 shown, the orthographic projection of the pad 211 on the first protective layer 1 and the orthographic projection of the pad auxiliary part 221 on the first protective layer 1 completely overlap. At this time, the same mask plate can be used when forming the pad 211 and the pad auxiliary part 221, thus simplifying the manufacturing process of the flexible circuit board 10 and reducing the manufacturing cost of the flexible circuit board 10.

[0134] Embodiments of the present disclosure also provide a method for manufacturing a flexible circuit board 10 for manufacturing the above flexible circuit board 10. As Figure 12 shown, the method for manufacturing the flexible circuit board 10 includes steps S1 to S4.

[0135] S1: As Figure 13A shown, provide a copper-clad substrate 01, the copper-clad substrate 01 includes a plurality of conductive layers 2 stacked in sequence, and one conductive layer 2 located at the top layer among the plurality of conductive layers 2 is the first conductive layer 21.

[0136] Exemplarily, the number of conductive layers 2 included in the above copper-clad substrate 01 may be one layer, two layers or multiple layers. Embodiments of the present disclosure do not limit this.

[0137] In addition, the copper-clad substrate 01 is composed of at least one copper-clad laminate. A copper-clad laminate, also known as a copper-clad foil laminate, is a plate-like material formed by impregnating a reinforcing material with resin and covering one or both sides with copper foil through hot pressing. Copper-clad laminates include single-sided copper-clad laminates and double-sided copper-clad laminates. Among them, a single-sided copper-clad laminate includes one insulating layer and one conductive layer located on one side of the insulating layer; a double-sided copper-clad laminate includes one insulating layer and two conductive layers located on both sides of the insulating layer.

[0138] When the copper-clad substrate 01 includes one conductive layer 2, the copper-clad substrate 01 may be composed of one single-sided copper-clad laminate. When the copper-clad substrate 01 includes multiple conductive layers 2, the copper-clad substrate 01 may be composed of multiple double-sided copper-clad laminates; or, it may be composed of multiple single-sided copper-clad laminates; or, it may be composed of multiple single-sided copper-clad laminates and multiple double-sided copper-clad laminates together. Embodiments of the present disclosure do not limit this. For example, as Figure 13A shown, the copper-clad substrate 01 is composed of one double-sided copper-clad laminate and one single-sided copper-clad laminate. At this time, the copper-clad substrate 01 includes three conductive layers 2.

[0139] S2: As Figure 13B shown, form a plurality of pads 211 in the first conductive layer 21.

[0140] Exemplarily, in this step, other conductive layers 2 in the copper-clad substrate 01 may be etched simultaneously to form conductive patterns (such as pads 211 and signal traces of the flexible circuit board 10) in the plurality of conductive layers 2 at the same time. Thereby, the manufacturing process of the flexible circuit board 10 can be simplified.

[0141] Exemplarily, when part of the signal traces of the flexible circuit board 10 are located in the first conductive layer 21, when forming a plurality of pads 211, this part of the signal traces can be formed in the first conductive layer 21 synchronously.

[0142] Specifically, the above step S2 may include: forming a layer of photoresist on the first conductive layer 21, and then exposing and developing the photoresist layer to form a plurality of openings on the photoresist layer. Then, using the developed photoresist layer as a mask, the corresponding part of the first conductive layer 21 in the openings is etched away to form the pads 211 and part of the signal traces.

[0143] Exemplarily, after this step, it may further include: forming an interlayer conduction structure to conduct the signal traces located in different conductive layers 2, or to conduct the pads 211 and the signal traces located in other conductive layers 2.

[0144] S3: As Figure 13C shown, a second protective layer 3 is formed on the side of the first conductive layer 21 away from other conductive layers 2; the second protective layer 3 has a plurality of first openings 31, and the plurality of first openings 31 respectively expose a part of the plurality of 211; the area of the orthographic projection of each first opening 31 on the first protective layer 1 is smaller than the surface area of the pad 211.

[0145] Among them, the surface area of the pad 211 can refer to the description in some of the above embodiments and will not be elaborated here.

[0146] Exemplarily, the material of the second protective layer 3 can refer to the description in some of the above embodiments and will not be elaborated here.

[0147] S4: As Figure 13D shown, a first protective layer 1 is formed on the side of the plurality of conductive layers 2 away from the second protective layer 3.

[0148] Exemplarily, the material of the first protective layer 1 can refer to the description in some of the above embodiments and will not be elaborated here.

[0149] It should be noted that some steps of the above manufacturing method can be executed simultaneously, or can be executed in an order different from Figure 12 shown. For example, the above steps S3 and S4 can be executed simultaneously, that is, the second protective layer 3 is formed on the side of the first conductive layer 21 away from other conductive layers 2, and the first protective layer 1 is formed on the side of the plurality of conductive layers 2 away from the second protective layer 3 at the same time.

[0150] The preparation method of the flexible circuit board 10 provided by some embodiments of the present disclosure can be used to prepare the flexible circuit board 10 in any of the above embodiments. In the flexible circuit board 10 prepared by this preparation method, the surface area of the pad 211 exposed by the first opening 31 is larger than the area of the positive projection of the first opening 31 on the first protective layer 1. When the optical component 20 and the flexible circuit board 10 are electrically connected through the bonding portion 30, the contact area between the pad 211 and the bonding portion 30 is relatively large, thereby enhancing the welding strength between the optical component 20 and the flexible circuit board 10, making the welding between the optical component 20 and the flexible circuit board 10 more firm, improving the welding quality between the optical component 20 and the flexible circuit board 10, and reducing the probability that the optical component 20 and the flexible circuit board 10 break at the welding point in the case of collision or vibration during transportation due to the insecure welding between the optical component 20 and the flexible circuit board 10, ensuring the effectiveness of the electrical connection between the optical component 20 and the flexible circuit board 10.

[0151] In some embodiments, the conductive layer 2 second closest to the second protective layer 3 among the multiple conductive layers 2 is the second conductive layer 22; the copper-clad substrate 01 further includes: an insulating layer 4 disposed between the first conductive layer 21 and the second conductive layer 22. Before forming the first protective layer 1 on one side of the multiple conductive layers 2 away from the second protective layer 3, the above preparation method further includes: forming a plurality of vias 41 in the insulating layer 4; forming a plurality of pad auxiliary portions 221 in the second conductive layer 22, and the pad 211 is connected to the pad auxiliary portion 221 through the via 41.

[0152] Among them, the material of the insulating layer 4 can refer to the description in some of the above embodiments and will not be elaborated here.

[0153] Exemplarily, conductive material can be filled in the via 41 by electroplating or other processes, so that the pad 211 and the pad auxiliary portion 221 are electrically connected. At this time, the pad 211 and the pad auxiliary portion 221 constitute a "double pad" design.

[0154] In this embodiment, the pad auxiliary portion 221 is formed in the second conductive layer 22 close to the first conductive layer 21, so that the pad 211 and the pad auxiliary portion 221 located in different conductive layers 2 constitute a "double pad" design, thereby improving the connection strength between the flexible circuit board 10 and the optical component 20 and ensuring the stability of the connection between the flexible circuit board 10 and the optical component 20.

[0155] The above is only the specific implementation manner of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present disclosure, thinking of changes or substitutions, should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claimed rights.

Claims

1. A flexible circuit board, comprising: A first protective layer; A plurality of conductive layers disposed on the first protective layer and stacked in sequence along a direction perpendicular to the first protective layer; And A second protective layer disposed on a side of the plurality of conductive layers away from the first protective layer; Wherein, among the plurality of conductive layers, the conductive layer closest to the second protective layer is a first conductive layer, and the first conductive layer includes a plurality of pads; the second protective layer is provided with a first opening at a position corresponding to the pad, and at least a part of the pad is exposed through the first opening; the area of the orthographic projection of each first opening on the first protective layer is smaller than the surface area of the pad.

2. The flexible circuit board according to claim 1, wherein, At least one groove is formed on a surface of the pad where it is exposed.

3. The flexible circuit board according to claim 2, wherein, The groove penetrates through the pad.

4. The flexible circuit board according to claim 2, wherein, The bottom wall of the groove is located within the pad.

5. The flexible circuit board according to claim 4, wherein, The side wall of the groove is flush with the edge of the first opening.

6. The flexible circuit board according to claim 1, wherein The orthographic projection of the end of the first opening away from the first protective layer on the first protective layer is located within the range of the orthographic projection of the end of the first opening close to the first protective layer on the first protective layer.

7. The flexible circuit board according to claim 1, wherein, The pad includes a sub - part and at least one branch - part; The sub - part includes a first node and a second node arranged at intervals, the branch - part includes an opposite first end and a second end, the first end is connected to the first node, and the second end is connected to the second node.

8. The flexible circuit board according to claim 7, wherein the pad includes a plurality of branch - parts located on both sides of the sub - part, and the plurality of branch - parts are symmetrically arranged with respect to the sub - part.

9. The flexible circuit board according to any one of claims 1 to 8, wherein, Among the plurality of conductive layers, the conductive layer next to the second protective layer is a second conductive layer; the second conductive layer includes a plurality of pad auxiliary parts; The flexible circuit board further includes: an insulating layer disposed between the first conductive layer and the second conductive layer, and a plurality of vias are provided in the insulating layer; The pad is connected to the pad auxiliary part through the via.

10. The flexible circuit board according to claim 9, wherein, The orthographic projection of the pad on the first protective layer and the orthographic projection of the pad auxiliary part on the first protective layer at least partially overlap.

11. A method for manufacturing a flexible circuit board, wherein, Provide a copper - clad substrate, the copper - clad substrate includes a plurality of conductive layers stacked in sequence, and one of the conductive layers located at the top layer is a first conductive layer; Form a plurality of pads in the first conductive layer; Form a second protective layer on a side of the first conductive layer away from other conductive layers; the second protective layer has a plurality of first openings, and each of the plurality of first openings exposes a part of the plurality of pads; the area of the orthographic projection of each first opening on the first protective layer is smaller than the surface area of the pad; Form a first protective layer on a side of the plurality of conductive layers away from the second protective layer.

12. The preparation method according to claim 11, wherein, Among the plurality of conductive layers, the conductive layer next to the second protective layer is a second conductive layer; the copper - clad substrate further includes: an insulating layer disposed between the first conductive layer and the second conductive layer; before forming the first protective layer on a side of the plurality of conductive layers away from the second protective layer, the manufacturing method further includes: Form a plurality of vias in the insulating layer; A plurality of pad assisting portions are formed in the second conductive layer, and the pads are connected to the pad assisting portions through vias.

13. A flexible circuit board assembly, comprising: A flexible circuit board, which is the flexible circuit board according to any one of claims 1 to 10; An optical component, which includes a plurality of pins; Bonding portions located in respective first openings of the flexible circuit board; the pins are bonded to the pads of the flexible circuit board through the bonding portions.

14. A display device, comprising: A display panel; A flexible circuit board assembly, located on a non-light-emitting side of the display panel and coupled to the display panel, and the flexible circuit board assembly is the flexible circuit board assembly according to claim 13.

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