Flexible circuit board with large bending radius, fingerprint module and electronic equipment

Abstract

The utility model provides a flexible circuit board with a large bending radius, a fingerprint module and electronic equipment, and relates to the technical field of flexible circuit boards. The flexible circuit board comprises a main board, a transition board, an adapter board, a first auxiliary board and a second auxiliary board, one end of the first auxiliary board is connected with one end of the transition board, the other end of the transition board is connected with one end of the main board, and one end of the adapter board is connected with one end, close to the main board, of the second auxiliary board. The other end of the adapter plate is bent and extends between the main plate and the first auxiliary plate and is connected to the transition plate; the adapter plate is used for being bent under the action of external force so that the upper plate face of the second auxiliary plate can be attached to the upper plate face of the first auxiliary plate, the adapter plate is located between the main plate and the first auxiliary plate after being bent, and the bending radius of the adapter plate is larger than or equal to a preset threshold value. Therefore, 'dead bending 'of the bending position of the flexible circuit board in a traditional scheme can be avoided, so that the circuit in the flexible circuit board is protected, and finally the reliability of the flexible circuit board after bending is improved.

Description

Technical Field

[0001] This application relates to the field of flexible circuit board technology, and in particular to a flexible circuit board with a large bending radius, a fingerprint module, and an electronic device. Background Technology

[0002] In related technologies, a fingerprint module includes a button, a fingerprint chip, and a flexible circuit board. The button and the fingerprint chip are soldered alternately to one side of the flexible circuit board and are located at opposite ends of the flexible circuit board in the length / width direction. Two steel sheets are attached to the other side of the flexible circuit board, corresponding to the button and the fingerprint chip respectively. Typically, the flexible circuit board needs to be folded in the length / width direction to attach the two steel sheets together and glue them. At this time, the bending point of the flexible circuit board will exceed the original shape design of the fingerprint module. At the same time, due to the space constraints of the whole device, the bending part of the flexible circuit board needs to be smaller and smaller, that is, the bending radius of the flexible circuit board needs to be reduced. This will inevitably increase the bending stress of the flexible circuit board. After the bending stress rebounds, it will weaken the adhesion between the two steel sheets, causing the button and the fingerprint chip to misalign. In order to avoid this misalignment, the bending point of the flexible circuit board can be "dead folded" during the production of the fingerprint module. This method can easily damage the internal circuitry of the flexible circuit board, making the flexible circuit board unable to perform its function and ultimately reducing the reliability of the flexible circuit board. Utility Model Content

[0003] This application provides a flexible circuit board with a large bending radius, a fingerprint module, and an electronic device, aiming to solve the problem of low reliability of flexible circuit boards after bending in related technologies.

[0004] To address the aforementioned drawbacks in related technologies, the first aspect of this application provides a flexible circuit board with a large bending radius. The flexible circuit board includes a main board, a transition board, an adapter board, a first sub-board, and a second sub-board. The first sub-board and the second sub-board are opposite to each other and spaced apart in the width direction of the flexible circuit board. The length directions of the first sub-board and the second sub-board are both consistent with the length direction of the flexible circuit board. One end of the first sub-board is connected to one end of the transition board, and the other end of the transition board is connected to one end of the main board. One end of the adapter board is connected to the end of the second sub-board adjacent to the main board, and the other end of the adapter board is bent and extended between the main board and the first sub-board and connected to the transition board. Specifically, the adapter board is used to bend under external force so that the upper surface of the second sub-board is attached to the upper surface of the first sub-board, and after bending, the adapter board is located between the main board and the first sub-board. The bending radius of the adapter board is greater than or equal to a preset threshold. The lower surface of the first sub-board is used to set the target chip, the lower surface of the second sub-board is used to set the target component, and the upper surface of the main board is used to set the main control chip. The target chip and the target component are used to electrically connect to the main control chip, and the target component is used to assist the operation of the target chip.

[0005] In some implementations, the first sub-board has a first and second side facing each other in the width direction of the flexible circuit board; the transition board has a third and fourth side facing each other in the width direction of the flexible circuit board; and the main board has a fifth and sixth side facing each other in the width direction of the flexible circuit board. Specifically, the first, third, and fifth sides are located on the same side of the flexible circuit board, are flush with each other, and are sequentially connected. The end of the adapter board not connected to the second sub-board is located on the fourth side. In one implementation, the vertical distance between the third and fourth sides is less than or equal to half the width of the first sub-board. In another implementation, the crease of the adapter board after bending is flush with the second or sixth side.

[0006] The second aspect of this application provides a fingerprint module, which includes a fingerprint chip, a button assembly, and the flexible circuit board provided in the first aspect of this application. The fingerprint chip is disposed on the lower surface of the first sub-board, and the button assembly is disposed on the lower surface of the second sub-board.

[0007] In some implementation schemes, the fingerprint module also includes a first reinforcing sheet and a second reinforcing sheet. The first reinforcing sheet is attached to the upper surface of the first sub-board, and the second reinforcing sheet is attached to the upper surface of the second sub-board. The adapter plate is specifically used to bend under external force so that the second reinforcing sheet is attached to the first reinforcing sheet. After the adapter plate is bent, an adhesive layer is formed between the attached first reinforcing sheet and the second reinforcing sheet.

[0008] In some implementations, the fingerprint module also includes a main control chip, which is located on the top surface of the motherboard and electrically connected to the fingerprint chip and the button assembly.

[0009] In some implementations, the button assembly includes a button circuit board and multiple buttons. The button circuit board is located on the lower surface of a second sub-board and electrically connected to the main control chip. The multiple buttons are spaced apart on the button circuit board, and each button has a conductive portion extending towards the button circuit board. The button circuit board has multiple conductive contacts corresponding to the conductive portions. Specifically, the conductive portion is used to electrically contact the conductive contacts when a button is pressed; the button circuit board is used to identify the user's pressing of each button and generate a corresponding electrical signal based on the electrical contact between the conductive contacts and the conductive portion; the main control chip is used to analyze the electrical signals and control the operation of the fingerprint chip accordingly.

[0010] The third aspect of this application provides an electronic device, which includes an electronic device body and a fingerprint module provided in the second aspect of this application, wherein the fingerprint module is disposed in the electronic device body.

[0011] The flexible circuit board provided in the first aspect of this application includes a main board, a transition board, an adapter board, a first sub-board, and a second sub-board. The first sub-board and the second sub-board are opposite to each other and spaced apart in the width direction of the flexible circuit board. The length direction of both the first sub-board and the second sub-board is consistent with the length direction of the flexible circuit board. One end of the first sub-board is connected to one end of the transition board, and the other end of the transition board is connected to one end of the main board. One end of the adapter board is connected to the end of the second sub-board adjacent to the main board. The other end of the adapter board is bent and extends between the main board and the first sub-board and is connected to the transition board. In practical applications, the adapter board can be bent to flip the second sub-board towards the first sub-board, thus attaching the upper surface of the second sub-board to the upper surface of the first sub-board. A main control chip can then be placed on the upper surface of the main board, a target chip on the lower surface of the first sub-board, and a target component to assist the target chip on the lower surface of the second sub-board. The target chip and target component are electrically connected to the main control chip, thus obtaining a module that performs a specific function. The specific function performed by the module varies depending on the target chip and target component. For example, if the module is a fingerprint module, the target chip is a fingerprint chip, and the target component is a button component. Specifically, after bending the adapter board, the entire adapter board is located between the main board and the first sub-board. This means that the bend in the adapter board will not extend beyond the main board / first sub-board, thus avoiding the problem of the flexible circuit board's bend exceeding the original shape design of the module in traditional solutions. Simultaneously, the bending radius of the adapter board will be greater than or equal to a preset threshold. Therefore, this application can increase the bending radius of the flexible circuit board (greater than or equal to a preset threshold) while ensuring that the bending point of the flexible circuit board does not exceed the original shape design of the module. This reduces the bending stress of the flexible circuit board and can effectively avoid the misalignment between the two steel sheets in the fingerprint module of the traditional solution. Thus, it is not necessary to "dead bend" the flexible circuit board at the bending point as in the traditional solution, thereby protecting the internal circuit of the flexible circuit board and ultimately improving the reliability of the flexible circuit board after bending.

[0012] The fingerprint module provided in the second aspect of this application has all the advantages of the flexible circuit board provided in the first aspect of this application because it includes the flexible circuit board.

[0013] The electronic device provided in the third aspect of this application has all the advantages of the fingerprint module provided in the second aspect of this application because it includes the fingerprint module provided in the second aspect of this application. Attached Figure Description

[0014] To more clearly illustrate the related technologies or the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the related technologies or the embodiments of this application will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application, and not all embodiments. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1(a) shows the structure of the flexible circuit board before it is folded in the length direction in the traditional scheme;

[0016] Figure 1(b) shows the structure of the flexible circuit board after it is folded in the length direction in the traditional scheme;

[0017] Figure 2(a) shows the structure of the flexible circuit board in the traditional scheme before it is folded in the width direction;

[0018] Figure 2(b) shows the structure of the flexible circuit board after it is folded in the width direction in the traditional scheme;

[0019] Figure 3(a) is a structural diagram of the flexible circuit board in the fingerprint module provided in the embodiment of this application before bending;

[0020] Figure 3(b) is a structural diagram of the flexible circuit board in the fingerprint module provided in the embodiment of this application after bending.

[0021] The labels in the attached diagrams are as follows: 1-Main board, 2-Transition board, 3-Adapter board, 4-First sub-board, 5-Second sub-board, 6-First reinforcing plate, 7-Second reinforcing plate, 8-Main control chip, 9-Button assembly. Detailed Implementation

[0022] In related technologies, a fingerprint module includes a button, a fingerprint chip, and a flexible circuit board. The button and the fingerprint chip are soldered alternately on one side of the flexible circuit board, and two steel sheets corresponding to the button and the fingerprint chip are attached to the other side of the flexible circuit board. Typically, a flexible circuit board needs to be folded in the length / width direction to bond the two steel sheets together. This folding point extends beyond the original design of the fingerprint module. Due to space constraints, the folded portion of the flexible circuit board must be smaller, reducing its bending radius. This inevitably increases the bending stress, which weakens the adhesion between the two steel sheets after the stress rebounds, causing misalignment between the button and the fingerprint chip. To avoid this misalignment, a "dead fold" can be performed on the flexible circuit board during fingerprint module production. This involves irreversible forced plastic deformation, causing the fold to lose its elasticity. However, this method easily damages the internal circuitry of the flexible circuit board, rendering it unusable and reducing reliability. The states of the flexible circuit board before and after folding in the length direction are shown in Figure 1(a) and Figure 1(b), and the states of the flexible circuit board before and after folding in the width direction are shown in Figure 2(a) and Figure 2(b), respectively. In view of this, the present application proposes a flexible circuit board with a large bending radius, a fingerprint module, and an electronic device in the embodiments below, in order to solve the above-mentioned drawbacks in the related technologies.

[0023] To make the objectives, technical solutions, and advantages of this application more apparent and understandable, this application will be clearly and completely described below in conjunction with its embodiments and corresponding drawings. Throughout, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. It should be understood that the embodiments of this application described below are only for explaining this application and are not intended to limit this application. That is, all other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. Furthermore, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0024] Please refer to Figures 3(a) and 3(b). Figure 3(a) is a structural diagram of the flexible circuit board in the fingerprint module before bending, and Figure 3(b) is a structural diagram of the flexible circuit board in the fingerprint module after bending. This embodiment provides a flexible circuit board with a large bending radius, including a main board 1, a transition board 2, an adapter board 3, a first sub-board 4, and a second sub-board 5. The length directions of the main board 1, transition board 2, adapter board 3, first sub-board 4, and second sub-board 5 are all consistent with the length direction of the flexible circuit board. Correspondingly, the width directions of the main board 1, transition board 2, adapter board 3, first sub-board 4, and second sub-board 5 are also consistent with the width direction of the flexible circuit board. Specifically, the first sub-board 4 and the second sub-board 5 are arranged opposite to each other and spaced apart in the width direction of the flexible circuit board (i.e., the first sub-board 4 and the second sub-board 5 are arranged side by side in the width direction of the flexible circuit board). One end of the first sub-board 4 is connected to one end of the transition board 2, and the other end of the transition board 2 is connected to one end of the main board 1. One end of the adapter board 3 is connected to the end of the second sub-board 5 adjacent to the main board 1, and the other end of the adapter board 3 is bent and extended between the main board 1 and the first sub-board 4 and connected to the transition board 2.

[0025] In this embodiment, the adapter board 3 is used to bend under the action of external force, so that the upper surface of the second sub-board 5 is attached to the upper surface of the first sub-board 4, and after bending, the adapter board 3 is located between the main board 1 and the first sub-board 4. The bending radius of the adapter board 3 is greater than or equal to a preset threshold. The lower surface of the first sub-board 4 is used to set the target chip (not shown in the figure), the lower surface of the second sub-board 5 is used to set the target component (not shown in the figure), and the upper surface of the main board 1 is used to set the main control chip 8. The target chip and the target component are respectively used to electrically connect to the main control chip 8, and the target component is used to assist the operation of the target chip.

[0026] In other words, in practical applications, the adapter board 3 can be bent so that the second sub-board 5 flips towards the first sub-board 4, thereby attaching the upper surface of the second sub-board 5 to the upper surface of the first sub-board 4. Then, the main control chip 8 can be set on the upper surface of the main board 1, and the target chip can be set on the lower surface of the first sub-board 4, and the target component that assists the target chip in working can be set on the lower surface of the second sub-board 5. The target chip and the target component are electrically connected to the main control chip 8 respectively. In this way, a module that realizes a specific function can be obtained. When the target chip and the target component are different, the specific function realized by the module is also different. If the module is a fingerprint module, then the target chip is a fingerprint chip (not shown in the figure), and the target component is a button component 9. Specifically, after bending the adapter board 3, the entire adapter board 3 is located between the main board 1 and the first sub-board 4. This means that the bend of the adapter board 3 will not extend beyond the main board 1 / first sub-board 4. This avoids the problem in traditional solutions where the bend of the flexible circuit board exceeds the original shape design of the module. At the same time, the bending radius of the adapter board 3 will be greater than or equal to a preset threshold. In addition, it should be noted that the preset threshold in this embodiment is designed based on the bending stress of the flexible circuit board. As long as the bending radius of the flexible circuit board is greater than or equal to the preset threshold, the bending stress of the flexible circuit board will not be too large. This solves the problem in traditional fingerprint modules where the adhesion between the two steel layers weakens due to excessive bending stress rebound, ultimately preventing the two steel layers from misaligning due to weakened adhesion.

[0027] As can be seen from the above, this embodiment can increase the bending radius of the flexible circuit board (greater than or equal to a preset threshold) while ensuring that the bending point of the flexible circuit board does not exceed the original shape design of the module. This reduces the bending stress of the flexible circuit board and effectively avoids the misalignment phenomenon between the two steel sheets in the fingerprint module of the traditional solution. Therefore, it is unnecessary to perform a "dead bend" at the bending point of the flexible circuit board as in the traditional solution, thus protecting the internal circuitry of the flexible circuit board and ultimately improving the reliability of the flexible circuit board after bending. Experiments show that for the same module, the bending radius of the flexible circuit board in the traditional solution can only reach 0.82mm, while the bending radius of the flexible circuit board in this embodiment is as high as 3.3mm.

[0028] In some embodiments, referring to Figures 3(a) and 3(b), the first sub-board 4 has a first side (not shown) and a second side (not shown) opposite each other in the width direction of the flexible circuit board, the transition board 2 has a third side (not shown) and a fourth side (not shown) opposite each other in the width direction of the flexible circuit board, and the main board 1 has a fifth side (not shown) and a sixth side (not shown) opposite each other in the width direction of the flexible circuit board; specifically, the first side, the third side and the fifth side are located on the same side of the flexible circuit board, the first side, the third side and the fifth side are flush and connected in sequence, and the end of the adapter board 3 that is not connected to the second sub-board 5 is provided on the fourth side after being bent and extended between the main board 1 and the first sub-board 4. In one embodiment, the vertical distance between the third and fourth sides (i.e., the width of the transition plate 2) is less than or equal to half the width of the first sub-plate 4 (i.e., the vertical distance between the first and second sides), and after the adapter plate 3 is bent, its crease is flush with the second or sixth side. At this time, the bending radius of the flexible circuit board (i.e., the vertical distance between the crease and the fourth side) is the largest, the bending stress of the flexible circuit board is the smallest, and the performance of the flexible circuit board is the best.

[0029] Please refer to Figures 3(a) and 3(b). This embodiment provides a fingerprint module, which includes a main control chip 8, a fingerprint chip (not shown), a button assembly 9, and the flexible circuit board described above. The main control chip 8 is disposed on the upper surface of the main board 1, the fingerprint chip is disposed on the lower surface of the first sub-board 4, and the button assembly 9 is disposed on the lower surface of the second sub-board 5. The fingerprint chip and the button assembly 9 are electrically connected to the main control chip 8. It should be noted that the fingerprint module of this embodiment can be applied to any electronic device with fingerprint recognition requirements in the art, such as smartphones, tablets, laptops, smart door locks, attendance machines, smart wearable devices, etc. The specific application can be selected according to actual needs, and this embodiment does not limit it to a single application. It should also be noted that electronic devices usually include an electronic device body, so placing the fingerprint module of this embodiment within the electronic device body can satisfy its fingerprint recognition requirements.

[0030] In some embodiments, referring still to Figures 3(a) and 3(b), the fingerprint module, in addition to the structure given above, also includes a first reinforcing sheet 6 and a second reinforcing sheet 7. The first reinforcing sheet 6 is attached to the upper surface of the first sub-plate 4, and the second reinforcing sheet 7 is attached to the upper surface of the second sub-plate 5. When the adapter plate 3 is bent under external force, the second reinforcing sheet 7 will fit into the first reinforcing sheet 6. The first reinforcing sheet 6 and the second reinforcing sheet 7 play the roles of structural support, electromagnetic shielding, and heat conduction and dissipation in the fingerprint module. It should be noted that both the first reinforcing sheet 6 and the second reinforcing sheet 7 are made of steel sheets. Of course, in other embodiments, the first reinforcing sheet 6 and the second reinforcing sheet 7 can also be made of other materials commonly used in the art, such as ceramics, aluminum alloys, and composite materials. The specific choice can be made according to actual needs, and this application does not limit it to a single material. Preferably, after the adapter plate 3 is bent, adhesive is applied between the first reinforcing sheet 6 and the second reinforcing sheet 7 that are attached together, so that an adhesive layer is formed between the first reinforcing sheet 6 and the second reinforcing sheet 7 that are attached together, thereby making the connection between the two tighter and reducing the risk of separation between the two; wherein, the adhesive used for adhesive application can be any adhesive commonly used in the art, such as epoxy resin adhesive, acrylic adhesive, polyurethane adhesive and silicone structural adhesive, etc., and can be selected according to actual needs, and this application does not make a unique limitation.

[0031] In some embodiments, still referring to Figures 3(a) and 3(b), the button assembly 9 includes a button circuit board (not shown) and multiple buttons (not shown). The button circuit board is disposed on the lower surface of the second sub-board 5 and electrically connected to the main control chip 8. The multiple buttons are spaced apart on the button circuit board, and each button has a conductive portion (not shown) extending toward the button circuit board. The button circuit board is provided with multiple conductive contacts (not shown) corresponding to the multiple conductive portions. Specifically, the conductive portion can electrically contact the conductive contact when the button is pressed; the button circuit board can identify the user's pressing of each button and generate a corresponding electrical signal based on the electrical contact between the conductive contact and the conductive portion; the main control chip 8 can analyze the electrical signal from the button circuit board and control the operation of the fingerprint chip accordingly, such as controlling the fingerprint chip to enable fingerprint recognition, add fingerprints, delete existing fingerprints, etc. Furthermore, it should be noted that technologies such as the button circuit board recognizing the user's press of each button and generating corresponding electrical signals, and the main control chip 8 parsing the electrical signals from the button circuit board and performing corresponding operations, are relatively mature technologies in this field, and therefore this application will not elaborate on them further.

[0032] The above embodiments are merely preferred implementations of this application and are not the only limitations on flexible circuit boards, fingerprint modules, and electronic devices with large bending radii. Those skilled in the art can flexibly customize these embodiments based on actual application scenarios. It is understood that through the implementation of the above embodiments of this application, a flexible circuit board is constructed using a motherboard 1, a transition plate 2, an adapter plate 3, a first sub-board 4, and a second sub-board 5. The first sub-board 4 and the second sub-board 5 are opposite to each other and spaced apart in the width direction of the flexible circuit board. The length directions of both the first sub-board 4 and the second sub-board 5 are consistent with the length direction of the flexible circuit board. One end of the first sub-board 4 is connected to one end of the transition plate 2, and the other end of the transition plate 2 is connected to one end of the motherboard 1. One end of the adapter plate 3 is connected to the end of the second sub-board 5 adjacent to the motherboard 1, and the other end of the adapter plate 3 is bent and extended between the motherboard 1 and the first sub-board 4 and connected to the transition plate 2. In practical applications, the adapter board 3 can be bent to flip the second sub-board 5 towards the first sub-board 4, thereby attaching the upper surface of the second sub-board 5 to the upper surface of the first sub-board 4. Subsequently, the main control chip 8 can be set on the upper surface of the main board 1, and the target chip can be set on the lower surface of the first sub-board 4. The target component that assists the target chip in working can be set on the lower surface of the second sub-board 5. The target chip and the target component are electrically connected to the main control chip 8, thus obtaining a module that realizes a specific function. When the target chip and the target component are different, the specific function realized by the module is also different. If the module is a fingerprint module, then the target chip is a fingerprint chip, and the target component is a button component 9. Specifically, after bending the adapter board 3, the entire adapter board 3 is located between the main board 1 and the first sub-board 4. This means that the bending point of the adapter board 3 will not exceed the main board 1 / first sub-board 4. This avoids the problem of the bending point of the flexible circuit board exceeding the original shape design of the module in the traditional solution. At the same time, the bending radius of the adapter board 3 will be greater than or equal to a preset threshold. Therefore, this application can increase the bending radius of the flexible circuit board (greater than or equal to a preset threshold) while ensuring that the bending point of the flexible circuit board does not exceed the original shape design of the module. This reduces the bending stress of the flexible circuit board and can effectively avoid the misalignment between the two steel sheets in the fingerprint module of the traditional solution. Thus, it is not necessary to "dead bend" the flexible circuit board at the bending point as in the traditional solution, thereby protecting the internal circuit of the flexible circuit board and ultimately improving the reliability of the flexible circuit board after bending.

[0033] It should be noted that the several embodiments shown above in this application are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. It should also be noted that in the textual description of this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply such an actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements may include not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus; and, without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0034] Furthermore, those skilled in the art can implement or use this application by practicing the several embodiments shown above. Various modifications to the embodiments shown above will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments not shown without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the several embodiments shown above, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A flexible circuit board with a large bending radius, characterized in that, The system includes a main board, a transition board, an adapter board, a first sub-board, and a second sub-board. The first sub-board and the second sub-board are opposite to each other and spaced apart in the width direction of the flexible circuit board. The length direction of both the first sub-board and the second sub-board is consistent with the length direction of the flexible circuit board. One end of the first sub-board is connected to one end of the transition board, and the other end of the transition board is connected to one end of the main board. One end of the adapter board is connected to the end of the second sub-board adjacent to the main board, and the other end of the adapter board is bent and extended between the main board and the first sub-board and connected to the transition board. The adapter board is used to bend under external force, so that the upper surface of the second sub-board is attached to the upper surface of the first sub-board, and after bending, the adapter board is located between the main board and the first sub-board. The bending radius of the adapter board is greater than or equal to a preset threshold. The lower surface of the first sub-board is used to set the target chip, the lower surface of the second sub-board is used to set the target component, and the upper surface of the main board is used to set the main control chip. The target chip and the target component are respectively used to electrically connect to the main control chip, and the target component is used to assist the operation of the target chip.

2. The flexible circuit board according to claim 1, characterized in that, The first sub-board has a first side and a second side opposite to each other in the width direction of the flexible circuit board, the transition plate has a third side and a fourth side opposite to each other in the width direction of the flexible circuit board, and the main board has a fifth side and a sixth side opposite to each other in the width direction of the flexible circuit board. The first side, the third side, and the fifth side are located on the same side of the flexible circuit board. The first side, the third side, and the fifth side are flush and connected in sequence. The end of the adapter plate that is not connected to the second sub-board is located on the fourth side.

3. The flexible circuit board according to claim 2, characterized in that, The vertical distance between the third side and the fourth side is less than or equal to half the width of the first sub-plate.

4. The flexible circuit board according to claim 3, characterized in that, After bending, the crease of the adapter plate is flush with the second side or the sixth side.

5. A fingerprint module, characterized in that, The device includes a fingerprint chip, a button assembly, and a flexible circuit board as described in any one of claims 1 to 4, wherein the fingerprint chip is disposed on the lower surface of the first sub-board, and the button assembly is disposed on the lower surface of the second sub-board.

6. The fingerprint module according to claim 5, characterized in that, It also includes a first reinforcing plate and a second reinforcing plate. The first reinforcing plate is attached to the upper surface of the first sub-plate, and the second reinforcing plate is attached to the upper surface of the second sub-plate. The adapter plate is specifically used to bend under external force so that the second reinforcing plate fits into the first reinforcing plate.

7. The fingerprint module according to claim 6, characterized in that, After the adapter plate is bent, an adhesive layer is formed between the first reinforcing sheet and the second reinforcing sheet that are attached to each other.

8. The fingerprint module according to claim 5, characterized in that, It also includes a main control chip located on the upper surface of the motherboard and electrically connected to the fingerprint chip and the button assembly.

9. The fingerprint module according to claim 8, characterized in that, The button assembly includes a button circuit board and multiple buttons. The button circuit board is disposed on the lower surface of the second sub-board and electrically connected to the main control chip. The multiple buttons are spaced apart and mounted on the button circuit board. Each of the multiple buttons has a conductive portion extending towards the button circuit board. The button circuit board is provided with multiple conductive contacts corresponding to the multiple conductive portions, wherein: The conductive part is used to make electrical contact with the conductive contact when the button is pressed; The button circuit board is used to identify the user's press of each button and generate a corresponding electrical signal based on the electrical contact between the conductive contact and the conductive part. The main control chip is used to analyze the electrical signals and control the operation of the fingerprint chip accordingly.

10. An electronic device, characterized in that, The device includes an electronic device body and a fingerprint module as described in any one of claims 5 to 9, wherein the fingerprint module is disposed within the electronic device body.

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