Flexible circuit board, 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 technology, and in particular to a flexible circuit board, a flexible circuit board assembly and a display device. Background Art

[0002] Flexible Printed Circuit (FPC) is currently widely used in many display devices such as mobile phones, laptops, wearable devices, tablet computers, etc. due to its high wiring density, light weight, thin thickness, and bendability. Utility Model Content

[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. A plurality of conductive layers are arranged on the first protective layer and are stacked in sequence in a direction perpendicular to the first protective layer. The second protective layer is arranged on a side of the plurality of conductive layers away from the first protective layer. Among the plurality of conductive layers, the conductive layer closest to the second protective layer is the 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 portion 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 the exposed surface of the pad.

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

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

[0007] In some embodiments, a sidewall of the groove is flush with an edge of the first opening.

[0008] In some embodiments, an orthographic projection of an end of the first opening away from the first protective layer on the first protective layer is located within a range of an orthographic projection of an 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-portion and at least one branch; the sub-portion includes a first node and a second node spaced apart, and the branch includes a first end and a second end opposite to each other, 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 branches located on both sides of the sub-portion, and the plurality of branches are symmetrically arranged with respect to the sub-portion.

[0011] In some embodiments, the conductive layer among the multiple conductive layers that is next closest to the second protective layer is the second conductive layer; the second conductive layer includes a plurality of pad auxiliary parts; the flexible circuit board also includes: an insulating layer arranged between the first conductive layer and the second conductive layer, a plurality of vias being arranged in the insulating layer; the pads are connected to the pad auxiliary parts through the vias.

[0012] In some embodiments, an orthographic projection of the pad on the first protection layer at least partially overlaps with an orthographic projection of the pad auxiliary portion on the first protection layer.

[0013] On the other hand, a method for preparing a flexible circuit board is provided. The preparation method comprises: providing a copper-clad substrate, the copper-clad substrate comprising a plurality of conductive layers stacked in sequence, wherein a conductive layer located at the top of the plurality of conductive layers is a 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, the plurality of first openings respectively exposing a portion 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; and 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 that is next closest to the second protective layer among the multiple conductive layers is the second conductive layer; the copper-clad substrate also includes: an insulating layer arranged between the first conductive layer and the second conductive layer; before the first protective layer is formed on the side of the multiple conductive layers away from the second protective layer, the preparation method also includes: forming a plurality of vias in the insulating layer; forming a plurality of pad auxiliary parts in the second conductive layer, and the pads are connected to the pad auxiliary parts through the vias.

[0015] On the other hand, a flexible circuit board assembly is provided, comprising: 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 comprising a plurality of pins; a bonding portion located in each first opening of the flexible circuit board; and the pins being bonded to the pads of the flexible circuit board through the bonding portion.

[0016] In another aspect, a display device is provided, comprising: the flexible circuit board assembly as described in any one of the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present disclosure, the following briefly introduces the drawings required for use in some embodiments of the present disclosure. Obviously, the drawings described below are only drawings of some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can also be obtained based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams, and are not limitations on the actual size of the products involved in the embodiments of the present disclosure, the actual process of the method, etc.

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

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

[0020] Figure 3A is a structural diagram of yet another flexible circuit board assembly according to some embodiments;

[0021] Figure 3B is a top view of yet another flexible circuit board assembly according to some embodiments;

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

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

[0024] Figure 5 is a structural diagram of yet another flexible circuit board assembly according to some embodiments;

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

[0026] Fig. 7A is a structural diagram of yet another flexible circuit board assembly according to some embodiments;

[0027] Figure 7B is a top view of yet another flexible circuit board assembly according to some embodiments;

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

[0029] Fig. 9 is a structural diagram of yet another flexible circuit board assembly according to some embodiments;

[0030] Fig.10 is a structural diagram of another flexible circuit board according to some embodiments;

[0031] Fig.11is a structural diagram of another flexible circuit board according to some embodiments;

[0032] Fig.12 is a flow chart of a method for manufacturing a flexible circuit board according to some embodiments;

[0033] FIG. 13A to FIG. 13D The figure is a structural diagram corresponding to each step in a method for manufacturing a flexible circuit board according to some embodiments. DETAILED DESCRIPTION

[0034] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present disclosure.

[0035] Unless the context requires otherwise, throughout the specification and claims, the term "comprise" and other forms thereof, such as the third person singular form "comprises" and the present participle form "comprising", are to be interpreted as open, 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" and the like are intended to indicate that specific features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representation of the above terms does 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] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "plurality" means two or more.

[0037] When 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, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. The term "coupled" indicates, for example, that two or more components are in direct physical or electrical contact. The term "coupled" or "communicatively coupled" may also refer to two or more components that are not in direct contact with each other, but still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited to the contents of this document.

[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: A only, B only, C only, 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: A only, B only, and a combination of A and B.

[0040] Additionally, the use of “based on” is meant to be open and inclusive, as a process, step, calculation, or other action “based on” one or more stated conditions or values ​​may, in practice, be based on additional conditions or values ​​beyond those stated.

[0041] It will be understood that when a layer or an element is referred to as being on another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may be present 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 exaggerated for clarity. Therefore, variations in the shapes relative to the drawings due to, for example, manufacturing techniques and / or tolerances are conceivable. Therefore, the exemplary embodiments should not be interpreted as being limited to the shapes of the regions shown herein, but include shape deviations due to, for example, manufacturing. For example, an etched region shown as a rectangle will typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shapes 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 fixed (e.g., still images), and whether text or text. 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 data assistants (PDAs), handheld or portable computers, GPS receivers / navigators, cameras, MP4 video players, camcorders, game consoles, watches, clocks, calculators, television monitors, flat panel displays, computer monitors, automotive displays (e.g., odometer displays, etc.), navigators, cockpit controls and / or displays, displays of camera views (e.g., displays of rear-view cameras in vehicles), electronic photographs, electronic billboards or signs, projectors, architectural structures, packaging, and aesthetic structures (e.g., displays of images of a piece of jewelry), etc.

[0044] In the embodiments of the present disclosure, the display device is taken as a wearable device for example, and the device may be a smart watch, a smart bracelet, etc.

[0045] Figure 1 FIG. 1 is a structural diagram of a display device according to some embodiments. Figure 1 As 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 components.

[0046] like Figure 1 As shown, the longitudinal section of the frame 100 is U-shaped, the display panel 300, the flexible circuit board assembly 400 and other electronic accessories are arranged in 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, and 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 used to display the picture is the light-emitting side, and the non-light-emitting side of the display panel 300 is the side of the display panel 300 opposite to the light-emitting side.

[0048] Exemplarily, the above-mentioned display panel 300 can be: an organic light emitting diode (OLED) display panel, a quantum dot light emitting diode (QLED) display panel, a micro light emitting diode (Micro LED) display panel, etc., and the present disclosure does not make any specific limitations on this.

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

[0050] In some examples, combined 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 , and 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 (Ambient Light Sensor, ALS device for short), 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, wherein 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 at the same time through the bonding portion 30 .

[0054] For example, 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), and 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] For example, Figure 3A As 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 arranged 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 arranged on a side of the plurality of conductive layers 2 away from the first protective layer 1.

[0057] The first protective layer 1 and the second protective layer 3 can both effectively protect the multiple conductive layers 2 .

[0058] Exemplarily, the first protective layer 1 may 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. For another example, 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 are not limited to this.

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

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

[0061] For example, the number of the conductive layers 2 may be two, three or more layers, etc. The embodiments of the present disclosure are not limited to this.

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

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

[0064] For example, Figure 3A As shown, the second protection layer 3 has a plurality of first openings 31 , and the plurality of first openings 31 respectively expose a portion 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 portion of one pad 211 .

[0066] It is understandable 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, voltage division, and impedance matching, capacitors for storing charge and releasing energy, inductors for storing magnetic energy and resisting current changes, and integrated circuits integrating multiple electronic components, etc., but are not limited thereto.

[0067] For example, Figure 3A As shown, the optical component 20 has a pin 201 , and the exposed portion of the pad 211 is connected to the pin 201 of the optical component 20 via a bonding portion 30 , thereby achieving 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 achieved through surface mounting technology (SMT for short).

[0069] Surface mount technology refers to a circuit assembly technology that mounts pinless or short-lead surface mount components on the surface of a circuit board or other substrate, and assembles them by soldering through methods such as reflow soldering or dip soldering. Specifically, in the embodiment of the present disclosure, the optical component 20 is mounted on the surface of the flexible circuit board 10, and is assembled by soldering through methods such as reflow soldering or dip soldering, thereby achieving 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, firstly, solder for reflow soldering is printed on the multiple pins 201 of the optical component 20 or the corresponding pads 211 on the flexible circuit board 10, and the multiple pins 201 of the optical component 20 are aligned and contacted with the pads 211 of the flexible circuit board 10. The solder is heated by a soldering technique such as reflow soldering or dip soldering to melt the solder, and then the solder is rapidly cooled to solidify to form a bonding portion 30. The bonding portion 30 is located in the first opening 31, and 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 may be one, two, or more, etc., which is not limited in the embodiments of the present disclosure.

[0072] For example, Figure 3A As shown, when the optical component 20 has a plurality of pins 201 , the number of pads 211 connected to one optical component 20 is also a plurality, and one pad 211 is connected to one pin 201 of the optical component 20 .

[0073] The multiple pads 211 connected to the same optical component 20 may 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 for transmitting different signals provided on the conductive layer 2. When the optical component 20 is connected to the flexible circuit board 10, the multiple pads 211 can transmit different signals from the multiple traces to the corresponding multiple pins 201 on the optical component 20.

[0075] In some examples, combined Figure 3A and Figure 3B , a 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 a circle, 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 a circle. For another example, the orthographic projection of the first opening 31 on the first protective layer 1 is a yoke shape, 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 a yoke shape. Figure 3B FIG. 3 schematically shows a case where the orthographic projection of the portion of the pad 211 exposed by the first opening 31 on the first protection layer 1 is a rectangular shape. In this case, the pad 211 can be called a rectangular pad.

[0077] In the thickness direction of the flexible circuit board 10, when the cross-sectional areas at different positions of the first opening 31 remain 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, the optical component 20 and the flexible circuit board 10 may be easily welded loosely. In the case of loose welding between the optical component 20 and the flexible circuit board 10, the display device 1000 including the flexible circuit board assembly 400 may be separated from the flexible circuit board 10 due to vibration or collision during assembly or transportation, thereby affecting the connectivity between the optical component 20 and the flexible circuit board 10 and affecting the functional use of the optical component 20.

[0079] Based on this, the present disclosure makes improvements to the flexible circuit board 10, such as Figure 4A to Figure 6 As shown, in the flexible circuit board 10 provided in the embodiment 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 pad 211 .

[0080] In some examples, combined 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 pad 211 on the first protective layer 1 .

[0081] It should be noted that the above-mentioned "surface area of ​​the pad 211" refers to: the sum of the surface areas of the outer surfaces of the pad 211 exposed by the first opening 31. The outer surface refers to the surface exposed to the outside. Specifically in the embodiment of the present disclosure, the surface area of ​​the pad 211 refers to the sum of the areas of the surfaces of the pad 211 exposed to the outside by the first opening 31.

[0082] For example, the number of the outer surfaces of the pad 211 exposed by the first opening 31 may be one or more, which is not limited in the embodiments of the present disclosure.

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

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

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

[0086] In such 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 (that is, the area of ​​the positive 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 portion of the pad 211 exposed by the first opening 31, that is, the cross-sectional area of ​​the first opening 31.

[0087] In this embodiment of the present disclosure, the surface area of ​​the pad 211 exposed by the first opening 31 is made larger than the area of ​​the positive projection of the first opening 31 on the first protective layer 1, that is, the contact area between the pad 211 and the bonding portion 30 is made larger, 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 of fracture at the welding point between the optical component 20 and the flexible circuit board 10 due to loose welding between the optical component 20 and the flexible circuit board 10 in the event of collision or vibration during transportation, thereby ensuring the effectiveness of the electrical connection between the optical component 20 and the flexible circuit board 10.

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

[0089] For example, the number of grooves A may be one, two or more. The embodiments of the present disclosure are not limited to this. Figure 4A and Figure 6 As shown, a groove A is formed on the exposed surface of the pad 211 .

[0090] For example, the orthographic projection of the groove A on the first protective layer 1 may be any one of a sawtooth shape, a cross shape or a polygon; wherein the polygon may 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 may also be any shape. The embodiments of the present disclosure are not limited to this.

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

[0092] It can be understood that the protrusion of the bonding part 30 and the groove A of the pad 211 match each other. Specifically, it can include: matching in shape, matching in quantity, and matching in positional relationship. Among them, the number of protrusions of the bonding part 30 is the same as the number of grooves A of the pad, and the protrusions of the bonding part 30 and the grooves A of the pad correspond one to one. That is, one protrusion of the bonding part 30 is located in one groove A of the pad.

[0093] Optionally, when the number of grooves A of the pad 211 is one, the number of protrusions of the bonding portion 30 is also one; when the number of grooves A of the pad 211 is two, the number of protrusions of the bonding portion 30 is also two. Figure 6 As shown in the figure, a groove A is formed on the surface of the exposed side of the pad 211. Figure 6 and Fig. 7A The bonding portion 30 includes a protrusion that extends into the groove A. At this time, in the cross-sectional view of the flexible circuit board assembly 400, the bonding portion 30 is in a “T” shape.

[0094] Exemplarily, the protrusion of the bonding portion 30 extends into the groove A of the pad 211 and fits tightly with the bottom wall and side walls of the groove A.

[0095] With the above arrangement, by providing a groove A on the surface of one side where the pad 211 is exposed, 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 area space that can accommodate the bonding portion 30 is increased, and when the bonding portion 30 is formed by a welding technique such as reflow soldering or dip soldering, the bonding portion 30 can also be filled in the groove A of the pad 211, thereby further improving 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 phenomenon of abnormal transmission between the optical component 20 and the flexible circuit board 10 caused by the breakage of the welding point between the optical component 20 and the flexible circuit board 10 due to collision during transportation.

[0096] It should be noted that there are many specific configuration methods for the groove A, which can be selected according to actual needs.

[0097] In one implementation, Figure 4A As shown, the bottom wall aa of the groove A is located in the pad 211. That is, the groove A only passes through a portion of the pad 211. At this time, the bottom wall aa and the side wall bb of the groove A are both located in the pad 211.

[0098] Combination Figure 4A and Figure 5 As shown, the bonding portion 30 contacts the bottom wall aa and the side wall bb of the groove A, thereby increasing the contact area between the solder and the pad 211, ensuring the welding quality between the optical component 20 and the flexible circuit board 10, and improving the product yield; moreover, the bottom wall aa and the side wall bb of the groove A are both located inside 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, thereby ensuring the effectiveness of the electrical connection between the optical component 20 and the flexible circuit board 10.

[0099] Further, such as Figure 4A As 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] For example, Figure 4A As 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, if Figure 5 As shown, a portion of the bonding portion 30 is located in 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 greatly increased, so that the material of the bonding portion 30 is increased, which is beneficial to further improve the welding quality between the optical component 20 and the flexible circuit board 10, and ensure the stability of signal transmission between the optical component 20 and the flexible circuit board 10.

[0103] Further, combined with Figure 4A and Figure 5 The bottom wall aa of the groove A is in contact with 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 of fracture at the welding point between the optical component 20 and the flexible circuit board 10 due to loose welding between the optical component 20 and the flexible circuit board 10 in the case of collision or vibration during transportation or other environments (for example, bending of the flexible circuit board 10), thereby greatly improving the yield of the product.

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

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

[0106] For example, Figure 6 As shown, the bottom wall aa of the groove A is located in the insulating layer close to the first conductive layer 21 .

[0107] Exemplary, combined Figure 6 to Figure 7B When the groove A runs through the pad 211 and the number of grooves A is one, the shape of the positive projection of the pad 211 on the first protective layer 1 is annular. At this time, the pad 211 is different from the conventional rectangular pad mentioned above and can be called an irregular pad 211.

[0108] In this case, a portion of the bonding portion 30 is located in the groove A and contacts the bottom wall aa and the side wall bb of the groove A, thereby increasing the contact area between the bonding portion 30 and the pad 211, thereby improving the welding quality between the optical component 20 and the flexible circuit board 10; moreover, the groove A runs through the pad 211, thereby further increasing the space in the groove A for accommodating the bonding portion 30, thereby 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, Figure 8 and Fig. 9 As shown, the orthographic projection of the end of the first opening 31 away from the first protective layer 1 on the first protective layer 1 is located 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 away 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 a trapezoid.

[0111] Among them, the end of the first opening 31 close to the first protective layer 1 can expose the entire surface of the pad 211 close to the second protective layer 3; it can also expose a part of the surface of the pad 211 close to the second protective layer 3, and the embodiments of the present disclosure are not limited to this.

[0112] In this example, if Fig. 9 As shown, the bonding portion 30 is filled in the first opening 31. The side wall of the pin 201 of the optical component 20 is in contact with the end of the first opening 31 away from the first protective layer 1, or there is a small gap between the two. At this time, the bonding portion 30 is in contact with the bottom surface and part of the side surface of the pin 201 of the optical component 20.

[0113] With the above arrangement, when the bonding portion 30 is formed by a soldering technique such as reflow soldering or dip soldering, since the cross-sectional area of ​​the end of the first opening 31 away 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, when the pin 201 of the optical component 20 extends into the first opening 31, the side surface of the pin 201 is not in contact with the first opening 31. Therefore, after the solder used to form the bonding portion 30 is liquefied, the liquid solder can crawl 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 at the pin 201 of the optical component 20 close to the pad 211, but also at the side surface of the pin 201 of the optical component 20 close to the pad 211. The bottom surface of the optical component 20 is also located on both sides of the pin 201 of the optical component 20, which further increases the contact area between the pin 201 of the optical component 20 and the bonding portion 30, thereby improving the welding quality between the optical component 20 and the flexible circuit board 10, and effectively avoiding the optical component 20 and the flexible circuit board 10 from being disconnected at the welding position, thereby increasing the stability between the optical component 20 and the flexible circuit board 10; moreover, by changing the size of the two ends of the first opening 31, a stable connection between the optical component 20 and the flexible circuit board 10 is achieved, the process is simple, the operation feasibility is strong, the processing cost is relatively low, and it can be mass-produced and used.

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

[0115] Among them, Fig.10 As shown, the sub-portion 211a includes a first node a1 and a second node a2 arranged at intervals, and the branch 211b includes a first end b1 and a second end b2 opposite to each other, 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 211b are connected in parallel.

[0116] For example, the number of the branches 211 b in the pad 211 may be one, two, or more, which is not limited in the embodiments of the present disclosure.

[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 away from the second protective layer 3 is connected to the trace on the flexible circuit board 10, thereby achieving electrical connection between the optical component 20 and the flexible circuit board 10.

[0118] In the case where the pad 211 includes a sub-portion 211a and at least one branch 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 211b. When one of the sub-portion 211a and the at least one branch 211b is poorly welded to the optical component 20, the optical component 20 can also be connected to the trace on the flexible circuit board 10 through the other of the sub-portion 211a and the at least one branch 211b. As a result, the probability of poor communication between the optical component 20 and the flexible circuit board 10 is reduced, and the effectiveness of the electrical connection between the optical component 20 and the flexible circuit board 10 is ensured.

[0119] As can be seen from the above, the portion of the pad 211 exposed by the first opening 31 is electrically connected to the optical component 20 via the bonding portion 30. Fig.10 As shown, the sub-portion 211a and the branch 211b of the pad 211 can be electrically connected to the optical component 20, and at this time, the first opening 31 can simultaneously expose the sub-portion 211a and the branch 211b of the pad 211. It can be understood that the first opening 31 also exposes the gap between the sub-portion 211a and the branch 211b, and the bonding portion 30 can also fill the gap, so that the material of the bonding portion 30 is increased, thereby increasing the welding strength between the optical component 20 and the flexible circuit board 10, 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.

[0120] Furthermore, when electrical connection can be achieved between the optical component 20 and the flexible circuit board 10 through the sub-part 211a or any one of the branches 211b, when the bonding part 30 is formed by welding techniques such as reflow soldering or dip soldering, the welding angle between the optical component 20 and the flexible circuit board 10 and the required amount of the bonding part 30 can be selected independently, thereby further improving the welding 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 relatively small. When the optical components 20 are mounted on the surface of the flexible circuit board 10 through 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 poor welding (for example, loose welding) between the ALS device and the flexible circuit board 10, thereby causing abnormal signal transmission between the ALS device and the flexible circuit board 10, affecting the product yield.

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

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

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

[0125] In this embodiment, the multiple branches 211b are independent of each other and can all realize the electrical connection between the optical component 20 and the flexible circuit board 10, thereby improving the effectiveness of the electrical connection between the optical component 20 and the flexible circuit board 10; moreover, the multiple branches 211b are symmetrically arranged about the sub-part 211a. When the bonding part 30 is formed by welding techniques such as reflow soldering or dip soldering, different positions of the pad 211 are subjected to uniform force, thereby ensuring the stability of welding and the welding quality between the optical component 20 and the flexible circuit board 10.

[0126] In some embodiments, Fig.11 As shown, the conductive layer 2 that is next closest to the second protective layer 3 among the multiple conductive layers 2 is the second conductive layer 22; the second conductive layer 22 includes a plurality of pad auxiliary parts 221; the flexible circuit board 10 also includes: an insulating layer 4 arranged between the first conductive layer 21 and the second conductive layer 22, and a plurality of vias 41 are arranged in the insulating layer 4; the pad 211 is connected to the pad auxiliary part 221 through the via 41.

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

[0128] For example, conductive material may be filled in the via hole 41 by electroplating or other processes, so as to electrically connect the pad 211 and the pad auxiliary portion 221. At this time, the pad 211 and the pad auxiliary portion 221 form a "double 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 a pad auxiliary portion 221, the pad 211 and the pad auxiliary portion 221 located on 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.

[0131] In some embodiments, Fig.11 As shown, the orthographic projection of the pad 211 on the first protection layer 1 at least partially overlaps with the orthographic projection of the pad auxiliary portion 221 on the first protection layer 1 .

[0132] It should be noted that the above-mentioned “the orthographic projection of the pad 211 on the first protective layer 1 at least partially overlaps with the orthographic projection of the pad auxiliary part 221 on the first protective layer 1” includes two situations: the orthographic projection of the pad 211 on the first protective layer 1 partially overlaps with the orthographic projection of the pad auxiliary part 221 on the first protective layer 1, and the orthographic projection of the pad 211 on the first protective layer 1 completely overlaps with the orthographic projection of the pad auxiliary part 221 on the first protective layer 1.

[0133] For example, Fig.11 As shown, the orthographic projection of the pad 211 on the first protective layer 1 completely overlaps with the orthographic projection of the pad auxiliary portion 221 on the first protective layer 1. At this time, the same mask plate can be used when forming the pad 211 and the pad auxiliary portion 221, thereby simplifying the manufacturing process of the flexible circuit board 10 and reducing the manufacturing cost of the flexible circuit board 10.

[0134] The embodiment of the present disclosure also provides a method for preparing a flexible circuit board 10, which is used to prepare the above-mentioned flexible circuit board 10. Fig.12 As shown, the method for preparing the flexible circuit board 10 includes steps S1 to S4.

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

[0136] For example, the number of the conductive layers 2 included in the copper-clad substrate 01 may be one layer, two layers, or multiple layers, which is not limited in the embodiments of the present disclosure.

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

[0138] When the copper-clad substrate 01 includes a conductive layer 2, the copper-clad substrate 01 may be composed of a 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, may be composed of multiple single-sided copper-clad laminates; or, may be composed of multiple single-sided copper-clad laminates and multiple double-sided copper-clad laminates. The embodiments of the present disclosure are not limited to this. For example, Fig.13A As shown, the copper-clad substrate 01 is composed of a double-sided copper-clad laminate and a single-sided copper-clad laminate. At this time, the copper-clad substrate 01 includes three conductive layers 2 .

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

[0140] Exemplarily, in this step, other conductive layers 2 in the copper-clad substrate 01 can be etched simultaneously, and conductive patterns (eg, pads 211 and signal traces of the flexible circuit board 10) can be formed simultaneously in multiple conductive layers 2. Thus, 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 the plurality of pads 211 , the part of the signal traces can be simultaneously formed on the first conductive layer 21 .

[0142] The above-mentioned step S2 may specifically include: forming a layer of photoresist on the first conductive layer 21, then exposing and developing the photoresist layer to form a plurality of openings on the photoresist layer, and then using the developed photoresist layer as a mask to etch and remove the portion of the first conductive layer 21 corresponding to the opening to form a pad 211 and a portion of the signal routing.

[0143] Exemplarily, after this step, the method may further include: forming an interlayer conductive structure to connect signal lines in different conductive layers 2 , or to connect pad 211 to signal lines in other conductive layers 2 .

[0144] S3: Fig. 13C As shown, a second protective layer 3 is formed on a 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 portion 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] The surface area of ​​the pad 211 may refer to the description in some of the above embodiments, which will not be repeated here.

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

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

[0148] For example, the material of the first protective layer 1 can refer to the description in some of the above embodiments, which will not be described again here.

[0149] It should be noted that some steps of the above-mentioned production method may be performed simultaneously, or may be performed in different steps. Fig.12 For example, the above steps S3 and S4 can be performed simultaneously, that is, the second protective layer 3 is formed on the side of the first conductive layer 21 away from the other conductive layers 2, and the first protective layer 1 is formed on the side of the multiple conductive layers 2 away from the second protective layer 3.

[0150] The method for preparing the flexible circuit board 10 provided in 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 the preparation method, the surface area of ​​the pad 211 exposed by the first opening 31 is greater than the area of ​​the orthographic 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 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, reducing the probability of fracture at the welding point between the optical component 20 and the flexible circuit board 10 due to the loose welding between the optical component 20 and the flexible circuit board 10 in the case of collision or vibration during transportation, and 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 that is next 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 the side of the multiple conductive layers 2 away from the second protective layer 3, the 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 pads 211 are connected to the pad auxiliary portions 221 through the vias 41.

[0152] The material of the insulating layer 4 can refer to the description in some of the above embodiments, which will not be described again here.

[0153] For example, conductive material may be filled in the via hole 41 by electroplating or other processes, so as to electrically connect the pad 211 and the pad auxiliary portion 221. At this time, the pad 211 and the pad auxiliary portion 221 form a "double pad" design.

[0154] In this embodiment, a 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 on 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 a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or substitutions that can be thought of by any person skilled in the art within the technical scope disclosed in the present disclosure should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A flexible circuit board, characterized in that: include: First protective layer; A plurality of conductive layers are disposed on the first protective layer and are sequentially stacked in a direction perpendicular to the first protective layer; as well as, A second protective layer disposed on a side of the plurality of conductive layers away from the first protective layer; Among them, the conductive layer closest to the second protective layer among the multiple conductive layers is the first conductive layer, and the first conductive layer includes multiple pads; the second protective layer is provided with a first opening at a position corresponding to the pad, and the first opening exposes at least a portion of the pad; 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, characterized in that: At least one groove is formed on the surface of the exposed side of the pad.

3. The flexible circuit board according to claim 2, characterized in that: The groove passes through the pad.

4. The flexible circuit board according to claim 2, characterized in that: The bottom wall of the groove is located inside the pad.

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

6. The flexible circuit board according to claim 1, characterized in that: An orthographic projection of an end of the first opening away from the first protective layer on the first protective layer is located within a range of an orthographic projection of an 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, characterized in that: The pad includes a sub-portion and at least one branch portion; The sub-portion includes a first node and a second node that are spaced apart from each other, and the branch includes a first end and a second end that are opposite to each other, wherein 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, characterized in that: The pad includes a plurality of branches located at both sides of the sub-portion, and the plurality of branches are symmetrically arranged with respect to the sub-portion.

9. The flexible circuit board according to any one of claims 1 to 8, characterized in that: The conductive layer next to the second protective layer among the plurality of conductive layers is a 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, wherein a plurality of via holes are disposed in the insulating layer; The pad is connected to the pad auxiliary portion through a via hole.

10. The flexible circuit board according to claim 9, characterized in that: An orthographic projection of the pad on the first protection layer at least partially overlaps with an orthographic projection of the pad auxiliary portion on the first protection layer.

11. A flexible circuit board assembly, characterized in that: include: A flexible circuit board, wherein the flexible circuit board is the flexible circuit board according to any one of claims 1 to 10; An optical component, the optical component comprising a plurality of pins; A bonding portion is located in each first opening of the flexible circuit board; the pin is bonded to the pad of the flexible circuit board through the bonding portion.

12. A display device, characterized in that: include: Display panel; A flexible circuit board assembly is located on the non-light-emitting side of the display panel and is coupled to the display panel. The flexible circuit board assembly is the flexible circuit board assembly as claimed in claim 11.

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