Circuit board, display module and electronic equipment

Abstract

The embodiment of the utility model provides a circuit board, a display module and electronic equipment, and relates to the technical field of electronic equipment. The circuit board comprises a first functional layer and a second functional layer. Wherein the first functional layer comprises a first non-bending part, a first transition part and a bending part which are connected in sequence. And the second functional layer comprises a second non-bending part and a second transition part which are connected in sequence. The second non-bending part and the first non-bending part are arranged in a stacked mode, and the second transition part and the first transition part are arranged in a stacked mode. The second transition part comprises a first part and a second part, the first part is connected with the second non-bending part, the second part is a part far away from the second non-bending part, and the second part is arranged in an unequal thickness mode. The stress distribution on the circuit board is relatively dispersed, the problem of circuit board cracking caused by stress concentration can be avoided, and the reliability of the circuit board is improved.

Description

Technical Field

[0001] The present application relates to the technical field of electronic equipment, and in particular to a circuit board, a display module and an electronic equipment. Background Art

[0002] With the advent of the 5G era, consumer electronic products with multi-functions and high-speed transmission performance are gaining popularity. With the gradual increase in functions and the improvement of various performances such as transmission speed, the number of electronic devices and wiring in electronic products is gradually increasing. In order to achieve multi-functions and high transmission speeds while ensuring the thinness and miniaturization of electronic products, the integration of electronic devices in electronic products also needs to be improved simultaneously.

[0003] The rigid-flexible circuit board is a combination of a rigid printed circuit board (RPCB) and a flexible printed circuit board (FPC) selectively laminated together. It has the advantages of being thin, light, easy to assemble, having good electrical transmission performance, and having better product reliability. It can achieve better electrical connections between electronic devices and is conducive to the realization of a highly integrated setting of electronic devices.

[0004] The rigid-flexible circuit board is used to realize the electrical connection between different electronic devices, so the reliability of the rigid-flexible circuit board has a great influence on the product yield of the electronic product. Utility Model Content

[0005] The embodiments of the present application provide a circuit board, a display module and an electronic device, the purpose of which is to disperse the stress distribution on the circuit board, thereby avoiding defects such as cracking of the circuit board, improving the reliability of the circuit board, and thus improving the product yield of the electronic device.

[0006] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0007] In a first aspect, a circuit board is provided, which includes a first functional layer and a second functional layer.

[0008] The first functional layer includes a first non-bending portion, a first transition portion and a bending portion connected in sequence. The second functional layer includes a second non-bending portion and a second transition portion connected in sequence. The second non-bending portion is stacked with the first non-bending portion, and the second transition portion is stacked with the first transition portion; the second transition portion includes a first part and a second part, the first part is connected to the second non-bending portion, the second part is a part away from the second non-bending portion, and the second part is arranged with unequal thickness.

[0009] In the circuit board provided in the embodiment of the present application, the second part of the second transition part is set to have unequal thickness to achieve a transition in thickness between the hard board part and the soft board part, thereby avoiding a direct connection between the hard board part and the soft board part, which would cause a large hardness drop and a large thickness drop at the connection between the two, resulting in stress concentration at the root of the soft board part, thereby causing the circuit board to break at this position, thereby effectively improving the reliability of the circuit board and improving the yield rate of electronic equipment.

[0010] In a possible implementation of the first aspect, the thickness of the second portion gradually decreases in a direction away from the first portion, so that the thickness of the circuit board at the location of the transition portion formed by the first transition portion and the second transition portion gradually decreases, so that the hardness of the transition portion gradually decreases along the direction from the hard board portion to the soft board portion, thereby achieving a gradual transition in thickness and hardness between the hard board portion and the soft board portion, thereby reducing the probability of cracking of the circuit board, improving the reliability of the circuit board, and improving the yield rate of the electronic equipment.

[0011] In a possible implementation manner of the first aspect, the second portion is arranged in a stepped shape, and along a direction away from the first portion, the step surface gradually approaches the first functional layer.

[0012] In the circuit board provided in the embodiment of the present application, the end of the second transition portion away from the second non-bending portion is arranged in a stepped shape, so that the thickness of the circuit board at the position of the transition portion formed by the first transition portion and the second transition portion is gradually reduced, so that the hardness of the transition portion is gradually reduced along the direction from the hard board portion to the soft board portion, thereby achieving a gradual transition of hardness between the hard board portion and the soft board portion, avoiding the situation where the hard board portion and the soft board portion are directly connected, where the hard board portion and the soft board portion have a large difference in hardness and thickness at the connection between the two, resulting in stress concentration at the root of the soft board portion, thereby causing the circuit board to break at this position, thereby effectively improving the reliability of the circuit board and improving the yield rate of electronic equipment.

[0013] In a possible implementation of the first aspect, the second functional layer is disposed on a first side of the first functional layer; the first side is a side of the bending direction of the bending portion, that is, the support force on the bending side of the first transition portion is strengthened to avoid the problem of the first transition portion being broken due to excessive bending tendency.

[0014] In a possible implementation of the first aspect, the second functional layer includes multiple sub-functional layers, each of which forms a step; some of the sub-functional layers are arranged on a first side of the first functional layer, and other sub-functional layers are arranged on a second side of the first functional layer. The first side is one side of the bending direction of the bending portion, and the second side is arranged opposite to the first side.

[0015] Thereby, supporting force and pulling force can be provided to the first transition portion at the same time, thereby further slowing down the tendency of the first transition portion to bend toward the first side, further reducing the probability of the first transition portion breaking, and improving the reliability of the circuit board.

[0016] In a possible implementation of the first aspect, the sub-functional layer located on the first side and the sub-functional layer located on the second side are symmetrically arranged with the plane where the first non-bending portion is located as the symmetry plane, thereby further improving the force uniformity of the upper and lower sides of the transition portion, thereby further improving the reliability of the circuit board.

[0017] In a possible implementation of the first aspect, the number of sub-functional layers located on the first side is greater than or equal to the number of sub-functional layers located on the second side. Without increasing the overall thickness of the circuit board, the second transition portion can be preferentially provided with sufficient and greater supporting force for the first transition portion, thereby improving the reliability of the circuit board.

[0018] In a possible implementation of the first aspect, the second functional layer includes multiple sub-functional layers, and each sub-functional layer has the same thickness. That is, the thickness difference between two adjacent sub-functional layers is kept consistent, so that the supporting force or pulling force provided by the second transition portion to the first transition portion can be uniformly reduced along the direction from the hard board portion to the soft board portion, thereby achieving a uniform transition of the force from the hard board portion to the soft board portion, further reducing the probability of the circuit board breaking, and improving the reliability of the circuit board.

[0019] In a possible implementation of the first aspect, the second functional layer includes multiple sub-functional layers, and the thickness of the multiple sub-functional layers gradually decreases in the direction close to the first functional layer. That is, the thickness difference between two adjacent sub-functional layers is also gradually reduced, and a uniform transition of force from the hard board part to the soft board part can also be achieved, further reducing the probability of the circuit board breaking and improving the reliability of the circuit board.

[0020] In a possible implementation of the first aspect, the second functional layer includes multiple sub-functional layers, and along the direction approaching the first functional layer, the distance between the ends of each two adjacent sub-functional layers away from the second non-bending portion in the first direction gradually increases; the first direction is the arrangement direction of the second non-bending portion and the second transition portion.

[0021] That is, along the direction approaching the first functional layer, the difference in length between adjacent sub-functional layers gradually increases, thereby further achieving a smooth transition of the force at the location of the transition portion, further improving the reliability of the circuit board, and taking into account the bending performance of the circuit board.

[0022] In a possible implementation of the first aspect, the second functional layer includes multiple layers of sub-functional layers, and the sizes of the multiple layers of sub-functional layers in the second direction gradually decrease along the direction approaching the first functional layer; the second direction is parallel to the surface of the first non-bending portion, and is perpendicular to the arrangement direction of the second non-bending portion and the second transition portion.

[0023] That is, along the direction approaching the first functional layer, the width of the sub-functional layer gradually decreases, so that the hardness of the end of the transition part close to the hard board part is large enough, and the end of the transition part close to the soft board part is soft enough, thereby further improving the reliability of the circuit board and taking into account the bending performance of the circuit board.

[0024] In a possible implementation manner of the first aspect, the second functional layer includes a plurality of sub-functional layers; each sub-functional layer includes at least one second insulating layer; and a material of the second insulating layer includes at least one of polypropylene and polyimide.

[0025] In a possible implementation of the first aspect, at least one sub-functional layer further includes a second insulating layer stacked with the second conductive layer; and at least one second insulating layer is disposed on a side of the second conductive layer away from the first functional layer. At least a portion of at least one second insulating layer is also located on an end surface of the second conductive layer away from the second non-bending portion. This avoids unexpected leakage problems at the end surface of the second conductive layer.

[0026] In a second aspect, an electronic device is provided, the electronic device comprising a display screen and a circuit board provided by any one of the embodiments in the first aspect, wherein the display screen is electrically connected to the circuit board.

[0027] According to a third aspect, an electronic device is provided. The electronic device comprises a rear case and the display module provided in the second aspect, wherein the rear case is arranged on one side of the display module.

[0028] The technical effects brought about by the display module in the second aspect and the electronic device in the third aspect can refer to the technical effects brought about by the design method of the circuit board in the first aspect, and will not be repeated here.

[0029] To sum up, the force at different positions of the circuit board provided in the embodiment of the present application (especially the connection position of the soft board part and the hard board part) is relatively uniform and dispersed, which effectively avoids the problems of breakage and wire breakage of the circuit board due to local stress concentration, thereby greatly improving the reliability of the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application;

[0031] Figure 2 A schematic diagram of the structure of a circuit board provided in an embodiment of the present application;

[0032] Figure 3 A cross-sectional view of an electronic device provided in an embodiment of the present application;

[0033] Figure 4 Another cross-sectional view of an electronic device provided by an embodiment of the present application;

[0034] Figure 5 A top view of a circuit board provided in an embodiment of the present application;

[0035] Figure 6 A partial enlarged view of a circuit board provided in an embodiment of the present application;

[0036] Figure 7 A cross-sectional view of a routing provided in an embodiment of the present application;

[0037] Figure 8 Another partial enlarged view of the circuit board provided in the embodiment of the present application;

[0038] Fig. 9 Another partial enlarged view of the circuit board provided in the embodiment of the present application;

[0039] Fig.10 Another top view of the circuit board provided in the embodiment of the present application;

[0040] Fig.11 Another cross-sectional view of an electronic device provided by an embodiment of the present application;

[0041] Fig.12 A cross-sectional view of a circuit board provided in an embodiment of the present application;

[0042] Fig.13 Another cross-sectional view of a circuit board provided in an embodiment of the present application;

[0043] Fig.14 A three-dimensional diagram of a circuit board provided in an embodiment of the present application;

[0044] Fig.15 Another stereoscopic view of a circuit board provided in an embodiment of the present application;

[0045] Fig.16 Another cross-sectional view of a circuit board provided in an embodiment of the present application;

[0046] Fig.17 Another cross-sectional view of a circuit board provided in an embodiment of the present application;

[0047] Fig.18 Another cross-sectional view of an electronic device provided by an embodiment of the present application;

[0048] Fig.19Another cross-sectional view of a circuit board provided in an embodiment of the present application;

[0049] Fig. 20 Another cross-sectional view of a circuit board provided in an embodiment of the present application;

[0050] Fig.21 Another cross-sectional view of a circuit board provided in an embodiment of the present application;

[0051] Fig. 22 Another top view of the circuit board provided in the embodiment of the present application;

[0052] Fig.23 Another top view of the circuit board provided in the embodiment of the present application;

[0053] Fig.24 This is a force simulation diagram of the circuit board provided in an embodiment of the present application. DETAILED DESCRIPTION

[0054] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments provided by the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present application.

[0055] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0056] Unless the context requires otherwise, throughout the specification and claims, the term "including" is interpreted as an open, inclusive meaning, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "exemplarily" 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 application. 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.

[0057] In the following, the terms "first", "second", etc. 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 application, unless otherwise specified, "multiple" means two or more.

[0058] When describing some embodiments, the expression "connection" and its derivatives may be used. The term "connection" 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 embodiments disclosed herein are not necessarily limited to the contents of this document.

[0059] “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.

[0060] “A and / or B” includes the following three combinations: A only, B only, and a combination of A and B.

[0061] As used herein, "parallel", "perpendicular", and "equal" include the situations described and situations similar to the situations described, and the range of the similar situations is within the acceptable deviation range, wherein the acceptable deviation range is determined by a person of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, "parallel" includes absolute parallelism and approximate parallelism, wherein the acceptable deviation range of approximate parallelism may be, for example, a deviation within 5°; "perpendicular" includes absolute perpendicularity and approximate perpendicularity, wherein the acceptable deviation range of approximate perpendicularity may also be, for example, a deviation within 5°. "Equal" includes absolute equality and approximate equality, wherein the acceptable deviation range of approximate equality may be, for example, the difference between the two equalities is less than or equal to 5% of either one.

[0062] 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 layers and regions are exaggerated for clarity. Therefore, variations in shape 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 deviations in shape due to, for example, manufacturing. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shapes of regions of the device, and are not intended to limit the scope of the exemplary embodiments.

[0063] In addition, the scenarios described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. A person of ordinary skill in the art can appreciate that, with the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0064] The embodiment of the present application provides an electronic device, which may be, for example, a mobile phone, a tablet computer, a personal digital assistant (PDA), a television, a smart wearable product (e.g., a smart watch, a smart bracelet), a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a rechargeable small household appliance (e.g., a soymilk machine, a sweeping robot), a drone, a radar, an aerospace equipment, an on-board device, a vehicle, and other different types of user devices or terminal devices; the electronic device may also be a network device such as a base station. The embodiment of the present application does not impose any special restrictions on the specific form of the electronic device.

[0065] For the sake of convenience, the following description takes the electronic device as a mobile phone as an example, which cannot be regarded as a specific limitation on the structural form of the electronic device.

[0066] Figure 1 A schematic diagram of the structure of an electronic device 1000 provided in an embodiment of the present application.

[0067] In some embodiments, Figure 1 As shown, the electronic device 1000 may include a display module 200 and a rear case 4 .

[0068] The display module 200 is used for displaying images, and the rear housing 4 is used for protecting the display module 200 from external damage.

[0069] participate Figure 1 , or see the subsequent Figure 3 , the rear shell 4 can be set on one side of the display module 200.

[0070] For example, Figure 1 As shown, the display module 200 includes a display screen 2 .

[0071] The display screen 2 has a light-emitting side and a non-light-emitting side opposite to each other. The light-emitting side refers to the side where the display surface of the display screen 2 is located (for example, Figure 1 The non-light-emitting side refers to the side opposite to the light-emitting side (e.g. Figure 1 to the right of center display 2).

[0072] For example, Figure 1 As shown, the display module 200 further includes a circuit board 100 , and the circuit board 100 can be electrically connected to the display screen 2 , so as to facilitate controlling the display screen 2 to realize functions such as image display or touch control.

[0073] For example, see Figure 1 The circuit board 100 can be connected to the end of the display screen 2 and then bent to the back side (non-light emitting side) of the display screen 2.

[0074] For example, see Figure 1 The electronic device 1000 may further include a cover plate 1 , a middle frame 3 and a rear shell 4 .

[0075] The cover plate 1 is arranged on the light-emitting side of the display screen 2 and fits the display screen 2. The middle frame 3 and the rear shell 4 are arranged on the non-light-emitting side of the display screen 2, and the rear shell 4 and the display screen 2 are located on both sides of the middle frame 3 respectively, and the middle frame 3 and the display screen 2 are arranged inside the rear shell 4.

[0076] For example, see Figure 1 The middle frame 3 may include a carrier plate and a frame surrounding the carrier plate. The electronic device 100 may also include a battery, a camera and other structures disposed on the carrier plate.

[0077] For example, Figure 1 As shown, the electronic device 100 may further include a circuit board assembly 5 .

[0078] For example, see Figure 1 , the circuit board assembly 5 can be located on the non-light-emitting side of the display screen 2. For example, the circuit board assembly 5 can be located between the carrier plate and the rear housing 4.

[0079] For example, Figure 1 As shown, a plurality of electronic devices 6 may be arranged on the circuit board assembly 5 .

[0080] Exemplarily, a plurality of electronic devices 6 may be disposed on one side of the circuit board assembly 5 , or electronic devices 6 may be disposed on both sides of the circuit board assembly 5 . The embodiments of the present application do not limit the specific location of the electronic devices 6 .

[0081] Exemplarily, the circuit board assembly 5 may include a main circuit board and a sub-circuit board. A plurality of electronic devices 6 may be arranged on the main circuit board and / or the sub-circuit board.

[0082] For example, the main circuit board in the circuit board assembly 5 can be used to integrate electronic devices 6 such as control chips. The control chip includes but is not limited to a system on chip (SOC), a charging management chip, a power management unit (PMU), a radio frequency chip (RF), a display chip, an application processor (AP), a double data rate synchronous dynamic random access memory (DDR), and a universal flash storage (UFS). Among them, the radio frequency chip can also be called a radio frequency power amplifier chip (RF PA).

[0083] The main circuit board may be a printed circuit board (PCB). Of course, the main circuit board may also be a flexible circuit board, a soft-hard combination circuit board, etc. Optionally, the main circuit board may be fixed between the middle frame 3 and the rear shell 4 by means of threaded connection, clamping, gluing, etc.

[0084] For example, the sub-circuit board of the circuit board assembly 5 may be integrated with electronic devices 6 such as universal serial bus (USB) devices. The USB device may be a USB type-C interface device, a USB type-A interface device, a USB type Micro-B interface device, or a USB type-B interface device. A socket is provided at a position corresponding to the USB device on the frame. Accessories such as a charger, earphones, and a data cable may be electrically connected to the USB device via the socket to achieve transmission of power, signals, and data.

[0085] The auxiliary circuit board may be a printed circuit board. Of course, the main circuit board may also be a flexible circuit board, a soft-hard combination circuit board, etc. The auxiliary circuit board may also be fixed between the middle frame 3 and the rear shell 4 by means of threaded connection, clamping, gluing or welding. The auxiliary circuit board is spaced apart from the main circuit board, and the two are electrically connected.

[0086] like Figure 1 As shown, the circuit board assembly 5 may include at least one circuit board 100. For example, the circuit board assembly 5 may include a circuit board 100 for electrically connecting to the display screen 2, or, Figure 1 The circuit board assembly 5 may further include a circuit board 100 disposed on a carrier plate of the middle frame 3 . The embodiment of the present application does not limit the number of circuit boards 100 in the electronic device 1000 or in the circuit board assembly 5 .

[0087] Exemplarily, the circuit board 100 may be a rigid-flexible circuit board.

[0088] Exemplarily, the circuit board 100 may be the aforementioned main circuit board, or may also be the aforementioned auxiliary circuit board, or may also be used to be electrically connected to a main circuit board or a width circuit board.

[0089] For example, the circuit board 100 may be the aforementioned main circuit board, and the circuit board 100 may be electrically connected to a display component in the display screen 2 so as to control the display screen 2 to display an image or video. For example, the circuit board 100 may be connected to a touch component in the display screen 2 so as to implement a touch function of the electronic device 1000.

[0090] The electronic device 1000 may include multiple circuit boards 100. For example, in addition to the circuit board 100 connected to the display screen 2, the electronic device 1000 may also include a circuit board 100 connected to other electronic devices 6 or other circuit boards. The embodiments provided in this application are only exemplary and do not limit the specific setting position and connection method of the circuit board 100.

[0091] Figure 2 A schematic diagram of the structure of a circuit board 100 provided in an embodiment of the present application. For example, Figure 2 As shown, the circuit board 100 includes a hard board portion 100A and a soft board portion 100B.

[0092] For example, see Figure 2 The circuit board 100 may include two hard board portions 100A located at both ends and a soft board portion 100B located between the two hard board portions 100A.

[0093] Here, the hard board portion 100A may include a portion of the circuit board 100 with a higher hardness, which may be provided with pads, pins, etc., so as to be electrically connected to structures such as the electronic device 6 and the display screen 2. The soft board portion 100B refers to a portion of the circuit board 100 with a lower hardness. Routing is provided in the soft board portion 100B to achieve electrical connection between the two hard board portions 100A, thereby achieving electrical connection between different electronic devices 6. The soft board portion 100B can be bent so that the circuit board 100 can adapt to different application scenarios.

[0094] The circuit board 100 (eg, the soft board portion 100B) has a certain degree of flexibility and can be bent.

[0095] Figure 3 This is a force analysis diagram of the circuit board 100 used in the electronic device 1000.

[0096] For example, see Figure 3When the display screen 2 is connected to the circuit board 100, one end of the circuit board 100 is connected to the display screen 2, and the other end is bent to the back side (ie, the non-luminous side) of the display screen 2 and connected to the electronic device 6 located on the back side of the display screen 2.

[0097] After the electronic device 1000 is assembled, the end user may press the module, which may cause slight elastic deformation of the bent circuit board 100. This long-term and repeated elastic deformation may cause the circuit board 100 to break and fail, especially at the junction of the hard board part 100A and the soft board part 100B of the circuit board 100. Since the stress here is more concentrated, it is more likely to break and fail.

[0098] For example, see Figure 3 When the display screen 2 is repeatedly pressed by the finger, the circuit board 100 connected to the display screen 2 will be subjected to elastic stress roughly perpendicular to the display screen 2, causing the circuit board 100 to repeatedly move slightly in a direction roughly perpendicular to the display screen 2, which can easily lead to breakage at the junction of the hard board part 100A and the soft board part 100B with large hardness and thickness differences.

[0099] In addition, some production lines of the electronic device 100 will also bend, snap together, rework, etc. the circuit board 100. These steps will also cause damage to the weaker positions of the circuit board 100 (such as the junction of the hard board part 100A and the soft board part 100B), causing the circuit board 100 to become disconnected or cracked.

[0100] Figure 4 and Figure 5 Some schematic diagrams of the circuit board 100 after it is cracked.

[0101] like Figure 4 and Figure 5 As shown, the circuit board 100 is easily located at a position of the soft board portion 100B close to the hard board portion 100A (such as Figure 4 and Figure 5 The fracture occurs as indicated by the arrow in the figure.

[0102] Figure 6 It is a partial enlarged view of the circuit board 100.

[0103] like Figure 6 As shown, the circuit board 100 includes a plurality of traces L. Defective lines such as disconnection or cracking of the circuit board 100 may easily cause the traces L in the circuit board 100 to be disconnected.

[0104] Figure 7 for Figure 6 A partial enlarged view of the disconnected position of trace L in the figure. Figure 8 for Figure 6 Cross-sectional view of the trace L at the disconnection location.

[0105] Figure 8 , Fig. 9 and Fig.10 FIG. 1 is a schematic diagram of cracking of the circuit board 100 in other embodiments.

[0106] See also Figure 7 to Figure 10 The cracking of the circuit board 100 may easily lead to the complete disconnection of the trace L on the circuit board 100, and the disconnection of the trace L may easily lead to the failure of the performance of the electrical structure connected to the circuit board 100, for example, in the connection with the display screen 2 (see Figure 1 ) When the circuit board 100 connected to the display screen 2 is cracked, it may cause touch failure (such as touch failure) or display failure (such as the appearance of black spots) of the display screen 2, and may even directly lead to the scrapping of the entire module, seriously affecting the product yield of the electronic device 1000. Fig.11 is a schematic diagram of a structure in which a circuit board 100 filled with glue is arranged in an electronic device 1000. Fig.12 for Fig.11 A partial enlarged view of the location where glue is set. Fig.13 A cross-sectional view of a circuit board 100 filled with glue.

[0107] In some embodiments, Fig.11 , Fig.12 and Fig.13 As shown, glue C may be filled at the junction of the hard board portion 100A and the soft board portion 100B to alleviate the problem of the aforementioned circuit board 100 being prone to cracking to a certain extent.

[0108] like Fig.11 , Fig.12 and Fig.13 As shown, by filling glue C at the junction of the hard board part 100A and the soft board part 100B, the hardness difference and thickness difference between the hard board part 100A and the soft board part 100B can be alleviated to a certain extent, thereby alleviating the tendency of cracking of the circuit board 100.

[0109] However, when filling glue C, the consistency of the glue amount dispensed is poor, which can easily affect the bending life of the circuit board 100, such as reducing the number of times the circuit board 100 can be bent, and the selection of glue C is relatively discrete, without a unified standard, which affects the uniformity of the performance of the product (such as the electronic device 1000). In addition, the efficiency of filling glue C is very low, requiring a large amount of glue dispensing equipment, which is costly, and the filling of glue C has little effect on solving the problem of cracking of the circuit board 100. The probability of cracking of the circuit board 100 is still high, and the probability of market withdrawal is high.

[0110] In order to effectively solve the above technical problems, an embodiment of the present application provides a circuit board 100.

[0111] Fig.14 and Fig.15 Some stereoscopic views of the circuit board 100 provided in the embodiment of the present application, Fig.16 A cross-sectional view of a circuit board 100 provided in an embodiment of the present application, Fig.17 A cross-sectional view of a circuit board 100 in a bent state provided in an embodiment of the present application, Fig.18 This is a schematic diagram of the structure of a circuit board 100 provided in an embodiment of the present application and applied in an electronic device 1000. Figure 19 to Figure 21 Some cross-sectional views of the circuit board 100 in an unfolded state provided in an embodiment of the present application.

[0112] like Figures 14 to 21 As shown, the circuit board 100 includes a rigid board portion 100A, a transition portion 100C and a flexible board portion 100B which are connected in sequence.

[0113] Among them, illustratively, the hardness of the hard board part 100A is the greatest, and a pad or pin may be provided thereon, so as to be electrically connected to the electronic device 6 or other electrical structures. The hardness of the soft board part 100B is the smallest, and it can be bent so that the circuit board 100 can be flexibly applied to different electrical connection scenarios. The transition part 100C is located between the hard board part 100A and the soft board part 100B, and its overall average hardness is less than the hardness of the hard board part 100A, and greater than the hardness of the soft board part 100B, so as to achieve the transition of hardness between the hard board part 100A and the soft board part 100B, and avoid the problem that the hard board part 100A and the soft board part 100B are directly connected, resulting in too large a hardness difference at the junction between the two, thereby causing the circuit board 100 to be easily broken at the junction.

[0114] For example, see Fig.15 and Fig.16 As shown, the circuit board 100 may include a six-layer board. Fig.15 Based on the orientation in the figure, from top to bottom, the six-layer board is respectively the first layer of copper, substrate + glue, the second and third layers of copper, substrate + glue, the fourth and fifth layers of copper, substrate + glue, and the sixth layer of copper.

[0115] Exemplarily, the first layer of copper, the second and third layers of copper, the fourth and fifth layers of copper, and the sixth layer of copper, each layer of the board includes at least one copper layer, and each layer of the board can also exemplarily include one or more of a copper-plated layer, a PI (Polyimide) substrate layer, a double-sided adhesive layer or a PP (Polypropylene) adhesive layer stacked with the copper layer. The substrate + adhesive board can include one or more of a PI substrate layer, a double-sided adhesive layer or a PP adhesive layer.

[0116] Fig.16 , Fig.17 , Figure 19 to Figure 21The stacking is only exemplary and does not limit the structure of the circuit board 100. In other embodiments, the circuit board 100 may include more or fewer boards than the six-layer board, and the stacking material in each layer of the board may be selectively different from that shown in the figure.

[0117] The circuit board 100 can achieve the structural setting of hardness transition as follows:

[0118] like Fig.17 , Figure 19 to Figure 21 As shown, the circuit board 100 includes a first functional layer 10 and a second functional layer 20 .

[0119] See also Fig.17 The first functional layer 10 includes a first non-bending portion 11, a first transition portion 12 and a bending portion 13 which are connected in sequence.

[0120] For example, see Fig.17 The first non-bending portion 11, the first transition portion 12 and the bending portion 13 are arranged in sequence along the first direction X.

[0121] The first direction X is the arrangement direction of the hard board portion 100A, the transition portion 100C and the soft board portion 100B. Fig.19 , when the circuit board 100 is unfolded, the first direction X is the direction from the hard board portion 100A of the circuit board 100 to the soft board portion 100B, or for example, referring to Figure 4 When the circuit board 100 is bent, the first direction X is the same as the direction of the bending path of the circuit board 100 .

[0122] For example, see Fig.17 The first non-bending portion 11, the first transition portion 12 and the bending portion 13 are integrally arranged.

[0123] For example, the first non-bending portion 11, the first transition portion 12 and the bending portion 13 are arranged in the same layer, wherein the first non-bending portion 11 is the portion of the first functional layer 10 used to form the hard board portion 100A, the first transition portion 12 is the portion of the first functional layer 10 used to form the transition portion 100C, and the bending portion 13 is used to form the soft board portion 100B.

[0124] For example, see Fig.17 The hardness, structure, shape, etc. of the first non-bending portion 11, the first transition portion 12 and the bending portion 13 can be the same.

[0125] For example, see Fig.17 The first functional layer 10 may include a first insulating layer 1A and a first conductive layer 1B which are stacked.

[0126] A plurality of traces L are provided in the first conductive layer 1B, and a portion of the traces L located in the hard board portion 100A may be electrically connected to an external electrical structure through a pad or a pin.

[0127] The first insulating layer 1A is used to achieve electrical insulation between adjacent first conductive layers 1B and to protect the first conductive layer 1B. Figure 4 , the upper side and the lower side of the first conductive layer 1B (with Fig.17 For example, the first insulating layer 1A may be provided on both sides, and at least one first insulating layer 1A may be provided between two adjacent first conductive layers 1B.

[0128] For example, see Fig.17 The first functional layer 10 may further include a first adhesive layer 1C. The first adhesive layer 1C may be a double-sided adhesive or a PP adhesive, which may be disposed between the first insulating layer 1A and the first conductive layer 1B to achieve fixation between the first insulating layer 1A and the first conductive layer 1B, thereby improving the reliability of the circuit board 100.

[0129] Exemplarily, the material of the first conductive layer 1B has conductivity, for example, may be a metal material, for example, may include at least one of copper (such as rolled copper, nickel silver or other copper materials), silver and other metals or alloys.

[0130] Exemplarily, the material of the first insulating layer 1A has electrical insulation properties, for example, may include an insulating organic polymer material, for example, may include polyimide (PI), polyethylene terephthalate (PolyethyleneTerephthalate, referred to as polyester or PET), polypropylene (PP) or polytetrafluoroethylene (Polytetrafluoroethylene, PTFE) and the like.

[0131] Exemplarily, the material of the first adhesive layer 1C has electrical insulation and adhesiveness, for example, the material of the first adhesive layer 1C may include glue having polypropylene (PP) material, or may include only pure glue.

[0132] Exemplarily, the first non-bending portion 11, the first transition portion 12 and the bending portion 13 are parts at different positions of the first functional layer 10, and all three may include the aforementioned first insulating layer 1A, first conductive layer 1B and first adhesive layer 1C.

[0133] See also Fig.17 The second functional layer 20 includes a second non-bending portion 21 and a second transition portion 22 connected in sequence.

[0134] For example, see Fig.17The second functional layer 20 is stacked with the first functional layer 10, and the second functional layer 20 is disposed at the end of the first functional layer 10, for example, see Figure 4 The second functional layer 20 may be stacked on the upper end of the first functional layer 10 .

[0135] Fig.17 In the figure, a part of the second non-bending portion 21 is disposed above the first functional layer 10, and another part is disposed below the first functional layer 10. For the convenience of illustration, Fig.17 Only the portion of the second non-bending portion 21 located below the first non-bending portion 11 is shown. It can be understood that the portion of the second functional layer 20 located above the first non-bending portion 11 also belongs to the second non-bending portion 21. The second transition portion 22 is the same. And the subsequent Fig. 20 and Fig.21 Same reason.

[0136] For example, see Fig.17 The second non-bending portion 21 and the second transition portion 22 are also arranged along the first direction X.

[0137] For example, see Fig.17 The second non-bending portion 21 and the second transition portion 22 are integrally arranged.

[0138] For example, the second non-bending portion 21 and the second transition portion 22 are arranged in the same layer, wherein the second non-bending portion 21 is the portion of the second functional layer 20 used to form the hard plate portion 100A, and the second transition portion 22 is the portion of the second functional layer 20 used to form the transition portion 100C.

[0139] Exemplarily, the second functional layer 20 may include a second insulating layer 2A and a second conductive layer 2B. The relevant designs of the second insulating layer 2A and the second conductive layer 2B may refer to the description of the first insulating layer 1A and the first conductive layer 1B in the above embodiment, which will not be repeated here.

[0140] Exemplarily, the second functional layer 20 may also include a second adhesive layer 2C. The relevant design of the second adhesive layer 2C may also refer to the description of the first adhesive layer 1C in the above embodiment, which will not be repeated here.

[0141] The division between the aforementioned parts (for example, between the first non-bending part 11, the first transition part 12, and the bending part 13, or for example, between the second non-bending part 21 and the second transition part 22) is only for the convenience of description, and does not actually divide the first functional layer 10 or the second functional layer 20 into multiple parts. There may be no obvious boundaries between the aforementioned parts.

[0142] See also Fig.17 The second functional layer 20 is stacked with the first functional layer 10 except the bending portion 13. Fig.17 As shown, the second non-bending portion 21 is stacked with the first non-bending portion 11 , and the second transition portion 22 is stacked with the first transition portion 12 .

[0143] Among them, see Fig.17 The second non-bending portion 21 and the first non-bending portion 11 are stacked to increase the thickness of the circuit board 100 at this position, thereby jointly forming the hard board portion 100A of the circuit board 100 .

[0144] For example, see Fig.17 The circuit board 100 may be provided with a metal through hole K penetrating the first non-bending portion 11 and the second non-bending portion 21, so as to facilitate the electrical connection between the first conductive layer 1B and the second conductive layer 2B, that is, to facilitate leading the first conductive layer 1B to the surface of the circuit board 100 to form a pad or a pin to achieve electrical connection with other electrical structures (such as the electronic device 6 or the display screen 2).

[0145] See also Fig.17 The second transition portion 22 and the first transition portion 12 are stacked together to form the transition portion 100C of the circuit board 100 .

[0146] See also Fig.19 The second transition portion 22 may include a first portion 221 and a second portion 222 , wherein the first portion 221 is connected to the second non-bending portion 21 , and the second portion 222 is a portion away from the second non-bending portion 21 .

[0147] That is, the first portion 221 is an end of the second transition portion 22 connected to the second non-bending portion 21, and the second portion 222 is an end of the second transition portion 22 away from the second non-bending portion 21. For example, see Fig.19 The first portion 221 is the left end of the second transition portion 22 , and the second portion 222 is the right end of the second transition portion 22 .

[0148] The first part 221 and the second part 222 are only for the convenience of describing the two ends of the second transition part 22, and do not actually divide the second transition part 22 into two parts. There may be no obvious boundary or obvious dividing position between the two parts. Any division that can clearly describe the two ends of the second transition part 22 is within the protection scope of the embodiments of the present application. For example, the embodiments of the present application do not limit the proportion of the first part 221 in the second transition part 22, or the shape of the first part 221. The first part 221 is only used to refer to the end of the second transition part 22 connected to the second non-bending part 21.

[0149] To avoid occlusion, Fig.19 The first part 221 and the second part 222 are not shown in other figures except Fig.19 Other drawings, such as Fig.17 In the embodiment, the second transition portion 22 can also be divided into a first portion 221 and a second portion 222, so as to distinguish the two ends of the second transition portion 22. Fig.17 The left end is the first part 221, and the right end is the second part 222.

[0150] See also Fig.19 , the second portion 222 is arranged with different thicknesses. Fig.17 , Fig.19 , Fig. 20 , Fig.21 The second transition portion 22 may be arranged with different thicknesses.

[0151] Here, “unequal thickness setting” means that the thicknesses at different positions of the second transition portion 22 (or the second portion 222 ) (ie, the size of the second transition portion 22 in a direction perpendicular to the first functional layer 10 ) are different.

[0152] In the circuit board 100 provided in the embodiment of the present application, the second part 222 of the second transition part 22 is set to have unequal thickness, thereby realizing the transition of thickness between the hard board part 100A and the soft board part 100B, avoiding the problem that when the hard board part 100A and the soft board part 100B are directly connected, the thickness difference between the two is too large, resulting in stress concentration at the root of the soft board part 100B, thereby causing the circuit board 100 to break at this position, thereby effectively improving the reliability of the circuit board 100 and improving the yield rate of the electronic device 1000.

[0153] For example, see Fig.17 , along the direction away from the first portion 221 (i.e., the arrangement direction of the second non-bending portion 21 and the second transition portion 22, and from the second non-bending portion 21 to the second transition portion 22, for example Fig.17 The thickness of the second transition portion 22 (the second portion 222) gradually decreases.

[0154] Here, “the thickness of the second transition portion 22 gradually decreases” may be, for example, that the end surface of the second transition portion 22 away from the second non-bending portion 21 is sloped, so that the thickness of the second transition portion 22 gradually decreases continuously from left to right.

[0155] Alternatively, “the thickness of the second transition portion 22 gradually decreases” may, for example, be that the end of the second transition portion 22 away from the second non-bending portion 21 is stepped, so that the thickness of the second transition portion 22 gradually decreases from left to right in stages.

[0156] See also Fig.17 , Figure 19 to Figure 21The end of the second transition portion 22 away from the second non-bending portion 21 is arranged in a stepped shape, and along the direction of the second non-bending portion 21 pointing to the second transition portion 22 (for example Fig.17 The step surface gradually approaches the first functional layer 10 .

[0157] The “step surface” refers to the surface of the stepped second transition portion 22 away from the first functional layer 10 , each step of the stepped second transition portion 22 corresponds to a step surface, and the distances between different step surfaces and the first functional layer 10 are different, thereby forming the stepped second transition portion 22 .

[0158] For example, Fig.17 Taking the orientation in as an example, the step located above the first functional layer 10 gradually decreases in the direction from the second non-bending portion 21 to the second transition portion 22 (that is, the step surface gradually approaches the first functional layer 10), and the step located below the first functional layer 10 gradually increases in the direction from the second non-bending portion 21 to the second transition portion 22 (similarly, the step surface gradually approaches the first functional layer 10).

[0159] The stepped second transition portion 22 can gradually reduce the hardness of the transition portion 100C along the direction from the hard board portion 100A to the soft board portion 100B, that is, achieve a gradual transition of the hardness from the hard board portion 100A to the soft board portion 100B, and achieve the dispersion of stress at the position where the hard board portion 100A and the soft board portion 100B are connected.

[0160] For example, see Fig.17 The second functional layer 20 includes a plurality of sub-functional layers 20', and each sub-functional layer 20' is used to form a step surface.

[0161] See also Fig.17 The left end surfaces of the plurality of sub-functional layers 20' are flush, and the length of the sub-functional layers 20' gradually increases along the direction close to the first functional layer 10, so that the right end of the plurality of sub-functional layers 20' forms a step shape. Here, the length of the sub-functional layer 20' refers to the size of the sub-functional layer 20' in the first direction X.

[0162] For example, see Fig.17 Each sub-functional layer 20' may include at least one second insulating layer 2A, at least one second conductive layer 2B or at least one second adhesive layer 2C.

[0163] For example, the second functional layer 20 may be stacked on only one end of the first functional layer 10 (eg Fig.17The second functional layer 20 may be stacked on both ends of the first functional layer 10, or the second functional layer 20 may be stacked on both ends of the first functional layer 10. That is, the second transition portion 22 with a stepped design may be arranged at at least one end of the first functional layer 10. For example, the second transition portion 22 with a stepped design may be arranged only at the end of the first functional layer 10 with a larger bending degree, and the end with a smaller bending degree may not be provided with a stepped second transition portion 22.

[0164] In the circuit board 100 provided in the embodiment of the present application, the end of the second transition portion 22 away from the second non-bending portion 21 is arranged in a stepped shape, so that the thickness of the circuit board 100 at the position of the transition portion 100C formed by the first transition portion 12 and the second transition portion 22 is gradually reduced, so that the hardness of the transition portion 100C is gradually reduced along the direction from the hard board portion 100A to the soft board portion 100B, thereby achieving a gradual transition of the hardness between the hard board portion 100A and the soft board portion 100B. After the bending portion 13 (i.e., the soft board portion 100B) is bent, driven by the bending portion 13, the transition portion 100C is also slightly bent, or at least has a tendency to bend. At this time, the stress is mostly concentrated on the transition portion 100C. When the user presses the display screen 2, refer to Fig.18 The stepped transition portion 100C can disperse the stress perpendicular to the display screen 2 on the circuit board 100 in a direction gradually parallel to the display screen 2, thereby reducing the magnitude of the stress perpendicular to the display screen 2 and avoiding excessive hardness and thickness differences at the connection between the hard board portion 100A and the soft board portion 100B when the hard board portion 100A and the soft board portion 100B are directly connected, resulting in stress concentration at the root of the soft board portion 100B (the end of the soft board portion 100B close to the hard board portion 100A), thereby causing the circuit board 100 to break at this position, thereby effectively improving the reliability of the circuit board 100 and improving the yield rate of the electronic device 1000.

[0165] In addition, the circuit board 100 provided in the embodiment of the present application has a simple structure and is relatively easy to prepare. For example, during the laser cutting of the second functional layer 20, a stepped setting of the end of the second functional layer 20 is achieved by controlling the position, depth, and number of laser cutting.

[0166] The following Table 1 is a schematic diagram of the thickness of a circuit board 100 provided in an embodiment of the present application.

[0167] Among them, column A is the thickness of the film layer structure on the side of the hard board part 100A away from the soft board part 100B, areas B and C are the thickness of each film layer corresponding to the hard board part 100A, D and E are the thickness of each film layer corresponding to the transition part 100C, and F is the thickness of each film layer corresponding to the soft board part 100B.

[0168] Table 1

[0169]

[0170] In some embodiments, Fig.19 As shown, the second functional layer 20 is disposed on the first side 10 a of the first functional layer 10 .

[0171] Among them, see Fig.17 and Fig.19 , the first side 10a is one side of the bending direction of the bending portion 13. For example, see Fig.19 In the unfolded state of the circuit board 100, the first side 10a is the direction to be bent of the bending portion 13 (the bending direction when bending in the subsequent process), for example Fig.19 or, for example, see Fig.17 In the bent state of the circuit board 100 , the first side 10 a is the bent concave side of the bent portion 13 .

[0172] After the bending portion 13 (i.e., the soft board portion 100B) is bent toward the first side 10a, driven by the bending portion 13, the transition portion 100C is also slightly bent toward the first side 10a, or at least has a tendency to bend toward the first side 10a. At this time, the stress is mostly concentrated on the transition portion 100C. In the embodiment of the present application, by arranging the second functional layer 20 on the first side 10a of the first functional layer 10, that is, arranging the second transition portion 22 arranged in a stepped manner on the first side 10a of the first transition portion 12, a strong support is formed for the first transition portion 12, thereby alleviating the stress of the first transition portion 12 provided with the wiring L in the transition portion 100C. The second transition portion 22 has a tendency to bend toward the first side 10a, thereby avoiding the disconnection of the routing L in the first transition portion 12. In addition, the second transition portion 22 is arranged in a stepped shape, so the supporting force formed by the second transition portion 22 arranged on the first side 10a of the first transition portion 12 on the first transition portion 12 gradually decreases along the direction of the hard board portion 100A pointing to the soft board portion 100B, thereby on the one hand ensuring support for the first transition portion 12 to avoid the first transition portion 12 from breaking, and on the other hand, the supporting force of the end of the second transition portion 22 close to the soft board portion 100B gradually weakens, thereby avoiding affecting the smooth bending of the bending portion 13 (i.e., the soft board portion 100B).

[0173] In some embodiments, Fig. 20 As shown, the second functional layer 20 includes a plurality of sub-functional layers 20 ′, wherein some of the sub-functional layers 20 ′ are disposed on the first side 10 a of the first functional layer 10 , and another portion of the sub-functional layers 20 ′ are disposed on the second side 10 b of the first functional layer 10 .

[0174] The first side 10 a is one side of the bending direction of the bending portion 13 , and the second side 10 b is disposed opposite to the first side 10 a .

[0175] For example, Fig. 20 The direction to be bent of the bending portion 13 is below the first functional layer 10, and the first side 10a is Fig. 20 The second side 10b is below the first functional layer 10, and the second side 10b is above the first functional layer 10.

[0176] In the embodiment of the present application, by providing a sub-functional layer 20' on both the first side 10a and the second side 10b of the first functional layer 10, the portion of the second transition portion 22 located on the first side 10a provides support for the first transition portion 12, slowing down the tendency of the first transition portion 12 to bend toward the first side 1a, so as to avoid the first transition portion 12 from breaking. At the same time, the portion of the second transition portion 22 located on the second side 10b can also provide a pulling force in the opposite direction of the bending to the first transition portion 12 bonded thereto, thereby further slowing down the tendency of the first transition portion 12 to bend toward the first side 1a, further reducing the probability of the first transition portion 12 breaking, and improving the reliability of the circuit board 100.

[0177] For example, see Fig. 20 In the case where part of the sub-functional layers 20' of the second functional layer 20 is arranged on the first side 10a of the first functional layer 10, and another part of the sub-functional layers 20' is arranged on the second side 10b of the first functional layer 10, the multiple sub-functional layers 20' on both sides are respectively arranged in a stepped shape, and the steps of both gradually decrease along the direction approaching the first functional layer 10.

[0178] That is, the second transition portion 22 provides the first transition portion 12 with a supporting force and a pulling force that are opposite to the bending direction of the first transition portion 12, and both the supporting force and the pulling force gradually decrease along the direction from the hard board portion 100A to the soft board portion 100B, thereby also dispersing the stress on the second transition portion 22 and realizing a gradual change in the hardness of the second transition portion 22 (gradually decreasing along the direction from the hard board portion 100A to the soft board portion 100B), thereby taking into account both the reliability and bendability of the circuit board 100.

[0179] In some embodiments, see Fig. 20 The number of sub-functional layers 20 ′ located on the first side 10 a is greater than the number of sub-functional layers 20 ′ located on the second side 10 b .

[0180] For example, see Fig. 20 The number of sub-functional layers 20 ′ located on the first side 10 a is five, and the number of sub-functional layers 20 ′ located on the second side 10 b is four.

[0181] By setting the number of layers of the sub-functional layer 20' located on the first side 10a to be greater than the number of layers of the sub-functional layer 20' located on the second side 10b, the second transition portion 22 can preferentially provide sufficient and greater supporting force (opposite to the bending direction) for the first transition portion 12 without increasing the overall thickness of the circuit board 100, thereby improving the reliability of the circuit board 100.

[0182] In some embodiments, see Fig.21 The number of sub-functional layers 20 ′ located on the first side 10 a is equal to the number of sub-functional layers 20 ′ located on the second side 10 b , for example, both are five layers.

[0183] By setting the number of layers of the sub-functional layer 20' located on the first side 10a to be the same as the number of layers of the sub-functional layer 20' located on the second side 10b, the second transition portion 22 provides substantially the same support force and tension force for the first transition portion 12, that is, the upper side and the lower side (with the first transition portion 12 having the same support force and tension force) of the first transition portion 12. Fig.21 The forces on the upper and lower sides of the first transition portion 12 and even the entire transition portion 100C are roughly the same, so that the forces on the upper and lower sides are relatively uniform, so that the circuit board 100 can flexibly adapt to a variety of different bending schemes. For example, before the final electronic device 1000 is fully assembled, the circuit board 100 can also be bent upward (in the form of a circle). Fig.21 The design of uniform force on the upper and lower sides of the transition portion 100C can protect the circuit board 100 from bending in different bending conditions, and has high reliability.

[0184] For example, see Fig.21 The sub-functional layer 20' located on the first side 10a and the sub-functional layer 20' located on the second side 10b are symmetrically arranged with the plane where the first non-bending portion 11 is located as the symmetry plane N. That is, the sub-functional layer 20' located on the first side 10a and the sub-functional layer 20' located on the second side 10b are the same in shape, length, thickness, etc., so that the force uniformity of the upper side and the lower side of the transition portion 100C can be further improved, thereby further improving the reliability of the circuit board 100.

[0185] In some embodiments, see Fig.19 The second functional layer 20 includes a plurality of sub-functional layers 20', and the thickness d1 of each sub-functional layer 20' is the same, that is, the thickness difference between two adjacent sub-functional layers 20' is kept consistent, so that the supporting force or pulling force provided by the second transition portion 22 to the first transition portion 12 can be uniformly reduced along the direction from the hard board portion 100A to the soft board portion 100B, thereby achieving a uniform transition of the force from the hard board portion 100A to the soft board portion 100B, further reducing the probability of the circuit board 100 breaking and improving the reliability of the circuit board 100.

[0186] In some embodiments, see Fig.21 and Fig. 22 The second functional layer 20 includes a multi-layer sub-functional layer 20', and the thickness d1 of the multi-layer sub-functional layer 20' gradually decreases along the direction approaching the first functional layer 10, that is, the thickness difference between two adjacent sub-functional layers 20' is also gradually reduced, and a uniform transition of force from the hard board part 100A to the soft board part 100B can also be achieved, further reducing the probability of fracture of the circuit board 100 and improving the reliability of the circuit board 100.

[0187] In other embodiments, the change in the thickness d1 of the sub-functional layer can also be adjusted as needed. For example, in order to avoid exposure of the conductive material in the sub-functional layer 20' (such as the second conductive layer 2B), a layer of insulating material (such as the second insulating layer 2A) can be added on the conductive material. In this case, the thickness d1 of the sub-functional layer 20' may be increased. That is, the aforementioned embodiments of the present application only provide an illustrative description of the thickness change of the sub-functional layer 20', and do not limit it. It can be understood that any other design of a change in the thickness d1 of the sub-functional layer 20' that can achieve a stepped setting of the second transition portion 22 is within the protection scope of the embodiments of the present application.

[0188] Fig. 22 and Fig.23 A top view of the circuit board 100 provided in an embodiment of the present application.

[0189] In some embodiments, see Fig.21 and Fig. 22 The second functional layer 20 includes a plurality of sub-functional layers 20'. Along the direction approaching the first functional layer 10, the spacing L1 between the ends of each two adjacent sub-functional layers 20' away from the second non-bending portion 21 in the first direction X gradually increases, that is, along the direction approaching the first functional layer 10, the difference in length d2 (the size in the first direction X) of adjacent sub-functional layers 20' gradually increases.

[0190] See also Fig.21 and Fig. 22 In the second transition portion 22, the end of the multi-layer sub-functional layer 20' close to the second non-bending portion 21 is flush, and by setting the difference in length d2 of adjacent sub-functional layers 20' along the direction close to the first functional layer 10 to gradually increase, the right side of the second transition portion 22 (with Fig.21 and Fig. 22 The orientation in the figure is taken as the standard) and is arranged in a stepped manner.

[0191] In the embodiment of the present application, by setting the difference in length d2 of adjacent sub-functional layers 20' along the direction close to the first functional layer 10 to gradually increase, the step surface is gradually increased along the direction from the hard board part 100A to the soft board part 100B in the step formed by the multiple sub-functional layers 20' located on the same side of the first functional layer 10, thereby further realizing a smooth transition of the force at the position of the transition part 100C, further improving the reliability of the circuit board 100, and taking into account the bending performance of the circuit board 100.

[0192] In some embodiments, see Fig.23 The second functional layer 20 includes a plurality of sub-functional layers 20 ′, and the size of the plurality of sub-functional layers 20 ′ in the second direction Y gradually decreases along the direction approaching the first functional layer 10 .

[0193] The second direction Y is parallel to the surface of the first non-bending portion 11 (eg Fig.21 The upper surface in the middle), and is perpendicular to the arrangement direction of the second non-bending portion 21 and the second transition portion 22, that is, perpendicular to the first direction X.

[0194] That is, along the direction approaching the first functional layer 10, the width d3 of the sub-functional layer 20' gradually decreases, so that the hardness of the end of the transition portion 100C close to the hard board portion 100A is large enough, and the end of the transition portion 100C close to the soft board portion 100B is soft enough, thereby further improving the reliability of the circuit board 100 and taking into account the bending performance of the circuit board 100.

[0195] The above-mentioned various embodiments can be combined arbitrarily. For example, see Fig.23 , along the direction close to the first functional layer 10, the length d2 of the sub-functional layer 20' gradually increases, and at the same time, the width d3 of the sub-functional layer 20' gradually decreases. The above-mentioned multiple embodiments can also be combined in other ways, which will not be described here.

[0196] In some embodiments, see Figure 19 to Figure 21 Each sub-functional layer 20' includes at least one second insulating layer 2A. Fig.19 Each sub-functional layer 20' may include only one second insulating layer 2A. Alternatively, each sub-functional layer 20' may include two or more second insulating layers 2A.

[0197] The thickness d1 of the sub-functional layer 20 ′ can be controlled by controlling the number of the second insulating layers 2A in the sub-functional layer 20 ′.

[0198] For example, see Figure 19 to Figure 21 The sub-functional layer 20' may further include a second adhesive layer 2C.

[0199] In some embodiments, see Figure 19 to Figure 21 , at least one sub-functional layer 20' further includes a second insulating layer 2A stacked with the second conductive layer 2B. Fig.19 In the same sub-functional layer 20', at least one second insulating layer 2A is disposed on the side of the second conductive layer 2B away from the first functional layer 10. It is understood that the embodiment of the present application does not limit the number of second conductive layers 2B included in the sub-functional layer 20'.

[0200] At least a portion of at least one second insulating layer 2A is also located on the end surface of the second conductive layer 2B away from the second non-bending portion 21 .

[0201] For example, see Fig.19 , the length of the second insulating layer 2A located above the second conductive layer 2B (the dimension in the first direction X) is controlled to be greater than the length of the second conductive layer 2B, so that the portion of the second insulating layer 2A that exceeds the second conductive layer 2B is arranged on the end face of the second conductive layer 2B away from the second non-bending portion 21, thereby avoiding unexpected leakage problems at the end face of the second conductive layer 2B.

[0202] Exemplarily, the laser cutting method (including cutting position and cutting timing, etc.) can be controlled so that the second insulating layer 2A wraps around the end face of the second conductive layer 2B. For example, the second conductive layer 2B can be cut first, and then the second conductive layer 2B, the second adhesive layer 2C, and the second insulating layer 2A are laminated together so that the second insulating layer 2A covers the surface and end face of the second conductive layer 2B, and then the multi-layer second insulating layer 2A is cut at different positions (the cutting position is away from the second non-bending portion 21 relative to the end face of the second conductive layer 2B) to form a stepped second transition portion 22.

[0203] For example, see Fig.19 The second insulating layer 2A covering the end surface of the second conductive layer 2B can be located in the same sub-functional layer 20' as the second conductive layer 2B it covers, or the sub-functional layer 20' where the second insulating layer 2A covering the end surface of the second conductive layer 2B is located is located on the side of the sub-functional layer 20' where the second conductive layer 2B it covers is located, away from the first functional layer 10. That is, the embodiment of the present application does not limit the position of the sub-functional layer 20' where the second insulating layer 2A covering the end surface of the second conductive layer 2B is located, and any second insulating layer 2A that can cover the end surface of the second conductive layer 2B is within the protection scope of the embodiment of the present application.

[0204] The following is a simulation analysis of the circuit board 100 provided in the aforementioned embodiment.

[0205] Table 2 Simulation parameter diagram

[0206] Micro-movement pressing force / N Global maximum strain / ue Maximum stress at the proximal end of the hard plate / ue Step-free design 15 22190 19850 With stepped design 15 22480 19840

[0207] As shown in Table 2, in the embodiment of the present application, after a stepped transition portion 100C is provided between the hard board portion 100A and the soft board portion 100B, the global maximum strain and the maximum stress at the end of the hard board portion 100A both change slightly, that is, the design of the stepped transition portion 100C does not affect the stability and reliability of the circuit board 100 structure.

[0208] Fig.24 It is a force simulation diagram of the circuit board 100.

[0209] pass Fig.24 It can also be seen from the force simulation diagram of the circuit board 100 that the forces on various parts of the circuit board 100 are relatively uniform and dispersed, that is, the probability of defects such as breakage of the circuit board 100 is low. The structural design of the circuit board 100 provided in the embodiment of the present application greatly improves the reliability of the circuit board 100.

[0210] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that a person skilled in the art can think of within the technical scope disclosed in the present disclosure should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A circuit board, It is characterized in that include: The first functional layer comprises a first non-bending portion, a first transition portion and a bending portion connected in sequence; The second functional layer includes a second non-bending portion and a second transition portion connected in sequence; the second non-bending portion is stacked with the first non-bending portion, and the second transition portion is stacked with the first transition portion; the second transition portion includes a first part and a second part, the first part is connected to the second non-bending portion, the second part is a part away from the second non-bending portion, and the second part is arranged with unequal thickness.

2. The circuit board according to claim 1, It is characterized in that The thickness of the second portion gradually becomes thinner in a direction away from the first portion.

3. The circuit board according to claim 1 or 2, It is characterized in that The second portion is arranged in a stepped shape, and along a direction away from the first portion, the stepped surface gradually approaches the first functional layer.

4. The circuit board according to any one of claims 1 to 3, It is characterized in that The second functional layer is disposed on a first side of the first functional layer; the first side is a side of a bending direction of the bending portion.

5. The circuit board according to any one of claims 1 to 3, It is characterized in that The second functional layer includes multiple sub-functional layers, each sub-functional layer forms a step; some of the sub-functional layers are arranged on the first side of the first functional layer, and other sub-functional layers are arranged on the second side of the first functional layer; The first side is one side of the bending direction of the bending portion, and the second side is arranged opposite to the first side.

6. The circuit board according to claim 5, It is characterized in that The sub-functional layer located on the first side and the sub-functional layer located on the second side are symmetrically arranged with the plane where the first non-bending portion is located as a symmetry plane.

7. The circuit board according to claim 5, It is characterized in that The number of sub-functional layers located on the first side is greater than or equal to the number of sub-functional layers located on the second side.

8. The circuit board according to any one of claims 1 to 7, It is characterized in that The second functional layer includes multiple sub-functional layers, and each sub-functional layer has the same thickness.

9. The circuit board according to any one of claims 1 to 7, It is characterized in that The second functional layer includes a plurality of sub-functional layers, and the thickness of the plurality of sub-functional layers gradually decreases along a direction approaching the first functional layer.

10. The circuit board according to any one of claims 1 to 9, It is characterized in that The second functional layer includes multiple sub-functional layers. Along the direction approaching the first functional layer, the distance between the ends of each two adjacent sub-functional layers away from the second non-bending portion in the first direction gradually increases; the first direction is the arrangement direction of the second non-bending portion and the second transition portion.

11. The circuit board according to any one of claims 1 to 10, It is characterized in that The second functional layer includes multiple sub-functional layers, and the sizes of the multiple sub-functional layers in the second direction gradually decrease along the direction approaching the first functional layer; the second direction is parallel to the surface of the first non-bending portion and perpendicular to the arrangement direction of the second non-bending portion and the second transition portion.

12. The circuit board according to any one of claims 1 to 11, It is characterized in that The second functional layer includes multiple sub-functional layers; each sub-functional layer includes at least one second insulating layer; and the material of the second insulating layer includes at least one of polypropylene and polyimide.

13. The circuit board according to claim 12, It is characterized in that At least one sub-functional layer further comprises a second conductive layer stacked with the second insulating layer; at least one second insulating layer is arranged on a side of the second conductive layer away from the first functional layer; Wherein, at least a portion of the at least one second insulating layer is also located on an end surface of the second conductive layer away from the second non-bending portion.

14. A display module, It is characterized in that include: The circuit board according to any one of claims 1 to 13; A display screen is electrically connected to the circuit board.

15. An electronic device, It is characterized in that include: The display module according to claim 14; The rear shell is arranged on one side of the display module.

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