Preparation method of functional module, functional module and electronic equipment

Abstract

The invention provides a preparation method of a functional module, the functional module and electronic equipment, and relates to the technical field of terminals. According to the preparation method of the functional module, the sacrificial layer is formed on the surface of the flexible circuit board, so that the sacrificial layer plays a buffering role when the boss is cut, and the boss is removed along with stripping of the sacrificial layer. Therefore, the boss is removed under the condition that the flexible circuit board is not damaged, the problems that the functional module is difficult to assemble and the appearance quality of the electronic equipment is reduced can be solved, and the user experience is improved.

Description

Technical Field

[0001] This application relates to the field of terminal technology, and in particular to a method for preparing a functional module, the functional module, and an electronic device. Background Technology

[0002] With the increasing popularity of full-screen displays, structures that mount functional modules such as fingerprint recognition modules on the sides of electronic devices are being adopted. These functional modules typically include a flexible circuit board, a substrate, a functional structure, and a molding compound. The functional structure is mounted on the substrate, and the molding compound is inserted into mounting holes in the electronic device's casing (specifically, the mid-frame). The molding compound serves as the functional module's external appearance component (such as a side button on a mobile phone), covering the functional structure. The substrate is soldered to the flexible circuit board, achieving electrical connection between the functional structure and the flexible circuit board. In related technologies, to achieve thinner and lighter designs and reduce costs, the substrate is omitted, and the functional structure is directly fabricated on the flexible circuit board. However, this method of assembling the functional module is difficult, and the assembled module reduces the appearance quality of the electronic device, negatively impacting the user experience. Summary of the Invention

[0003] This application provides a method for preparing a functional module, the functional module, and an electronic device, which can solve the problems of difficult assembly of functional modules and reduced appearance quality of electronic devices, thereby improving the user experience.

[0004] In a first aspect, embodiments of this application provide a method for fabricating a functional module. The method includes: providing a flexible circuit board; forming a functional structure on a first side of the flexible circuit board in the thickness direction, the functional structure being located in a preset molding compound region; forming a sacrificial layer on the first side of the flexible circuit board, the flexible circuit board including a trace area connected to the preset molding compound region, the sacrificial layer covering at least a portion of the trace area and extending from the trace area into the preset molding compound region; forming a molding compound layer on the side of the functional structure and the sacrificial layer facing away from the flexible circuit board, the molding compound layer covering the functional structure; cutting the molding compound layer in the thickness direction along the boundary of the preset molding compound region connected to the trace area; and peeling off the sacrificial layer to remove the molding compound layer located outside the preset molding compound region on the functional module.

[0005] In this way, by forming a sacrificial layer on the surface of the flexible circuit board, the sacrificial layer acts as a buffer when cutting the boss, and the boss is removed along with the peeling off of the sacrificial layer. Therefore, removing the boss without damaging the flexible circuit board solves the problems of difficult assembly of functional modules and reduced appearance quality of electronic devices, thus improving the user experience.

[0006] According to the first aspect, the sacrificial layer does not overlap with the functional structure in the thickness direction of the flexible circuit board. This allows the formed molding compound to completely cover the functional structure, thereby protecting it.

[0007] According to the first aspect, or any implementation of the first aspect above, the length of the sacrificial layer extending from the junction of the lead-out area and the preset molding compound area to the preset molding compound area is greater than the cutting error threshold. In this way, during the actual cutting of the boss, it can be ensured that the sacrificial layer acts as a buffer, and the boss is removed along with the peeling off of the sacrificial layer.

[0008] According to the first aspect, or any implementation thereof, forming a sacrificial layer on the first side of the flexible circuit board includes: forming a sacrificial layer across the entire first side of the flexible circuit board; forming a cutout portion on the sacrificial layer, wherein the cutout portion is located within a pre-defined molding compound area. In this way, when using an injection mold for mold closing, the bottom circumference of the injection mold can be tightly fitted with the sacrificial layer, thereby preventing leakage of the injection molding material. Furthermore, since the sacrificial layer is laid across the entire surface of the flexible circuit board, any subsequent molding compound layer formed on top of the sacrificial layer can be removed. Therefore, when closing the injection mold, there is no need to consider mold closing accuracy; simply placing the pre-defined molding compound area within the injection mold is sufficient, thus reducing operational complexity.

[0009] According to the first aspect, or any implementation of the first aspect above, the length of the recessed portion relative to the boundary of the preset molding area is greater than the cutting error threshold. This ensures that the sacrificial layer acts as a buffer during the actual cutting of the boss, and that the boss is removed as the sacrificial layer peels off.

[0010] According to the first aspect, or any implementation of the first aspect above, the sacrificial layer is prepared using high-temperature adhesive tape. This allows for the direct use of existing high-temperature adhesive tape as the sacrificial layer, reducing the difficulty of its preparation and improving processing efficiency.

[0011] According to the first aspect, or any implementation thereof, cutting the molding layer in the thickness direction along the boundary of the preset molding area connected to the lead-out area includes: cutting the molding layer along the boundary of the preset molding area connected to the lead-out area until the cutting depth in the sacrificial layer reaches a preset depth, wherein the preset depth is less than the thickness of the sacrificial layer. This ensures that the cutting depth reaches the sacrificial layer, guaranteeing that the boss is removed along with the sacrificial layer.

[0012] According to the first aspect, or any implementation of the first aspect above, after providing the flexible circuit board, the method further includes: forming a reinforcing plate on a second side in the thickness direction of the flexible circuit board. In this way, the reinforcing plate supports the flexible circuit board, ensuring that the flexible circuit board remains flat, preventing dead bends or breaks in the flexible circuit board, and improving the yield of component mounting and injection molding on the surface of the flexible circuit board.

[0013] According to the first aspect, or any implementation of the first aspect above, after peeling off the sacrificial layer to remove the molding compound layer on the functional module located outside the preset molding compound area, the method further includes: peeling the reinforcing plate off the flexible circuit board. This not only ensures the flatness of the functional structure and molding compound during the fabrication of the functional module, but also reduces the thickness of the functional module.

[0014] According to the first aspect, or any implementation thereof, the reinforcing plate is adhered to the flexible circuit board by an adhesive layer; the viscosity of the adhesive layer on the side adhered to the reinforcing plate is less than the viscosity of the adhesive layer on the side adhered to the flexible circuit board. In this way, when the reinforcing plate is peeled off, the adhesive layer can remain on the reinforcing plate, thereby avoiding adhesive residue on the flexible circuit board and allowing the reinforcing plate and adhesive layer to be peeled off from the flexible circuit board together.

[0015] Secondly, embodiments of this application also provide a functional module. This functional module is fabricated using a method for fabricating a functional module according to any of the implementations of the first aspect described above. The functional module includes a flexible circuit board; a functional structure located on a first side in the thickness direction of the flexible circuit board; and a molding compound covering the functional structure, with a groove formed between the side end of the molding compound and the flexible circuit board.

[0016] According to the second aspect, the functional module is a fingerprint recognition module, and the functional structure includes a fingerprint chip, which is fixed on a flexible circuit board and electrically connected to the flexible circuit board.

[0017] According to the second aspect, or any implementation of the second aspect above, the functional module is a capacitive detection module, and the functional structure includes multiple capacitor structures spaced apart along the length direction of the molding compound. The capacitor structure includes electrodes, and the electrodes are located in the conductive layer of the flexible circuit board.

[0018] Thirdly, embodiments of this application also provide an electronic device. The electronic device includes a housing and a functional module implemented according to any of the second aspects above. The housing includes a mid-frame, the mid-frame includes an annular border, and mounting holes are provided on the border. The plastic encapsulation of the functional module passes through the mounting holes.

[0019] According to the third aspect, the electronic device also includes a motherboard, which is placed inside the housing, and the flexible circuit boards of the functional modules are electrically connected to the motherboard.

[0020] According to the third aspect, or any of the above implementations of the third aspect, the flexible circuit board is an adapter board.

[0021] According to the third aspect, or any of the above implementations of the third aspect, the electronic device also includes volume buttons and a power button, and the plastic encapsulation of the function module is reused as either volume buttons or a power button.

[0022] According to the third aspect, or any of the above implementations of the third aspect, the functional module is a capacitive detection module, and the electronic device also includes volume buttons and a power button, which are integrated into the plastic package of the capacitive detection module.

[0023] According to the third aspect, or any implementation of the third aspect above, the functional module is a capacitive detection module, the electronic device also includes volume buttons and a power button, the mounting holes include a first mounting hole, a second mounting hole and a third mounting hole, the volume buttons are inserted into the first mounting hole, the power button is inserted into the second mounting hole, the plastic seal of the capacitive detection module is inserted into the third mounting hole, and the plastic seal is used as a camera control button.

[0024] According to the third aspect, or any implementation of the third aspect above, the functional module is a capacitive detection module, which includes a first capacitive detection module and a second capacitive detection module. The electronic device also includes volume buttons and a power button. The mounting holes include a first mounting hole and a second mounting hole. The first plastic seal of the first capacitive detection module passes through the first mounting hole, and the second plastic seal of the second capacitive detection module passes through the second mounting hole. The volume buttons and the power button are integrated into the first plastic seal, and the second plastic seal is used as a camera control button. Attached Figure Description

[0025] Figure 1 This is a schematic diagram illustrating the structure of a functional module as an example.

[0026] Figure 2 for Figure 1 The flowchart of the manufacturing process of the functional module is shown below;

[0027] Figure 3 for Figure 1 The diagram shows the appearance of the functional module.

[0028] Figure 4 This is a schematic diagram illustrating the structure of another functional module as an example;

[0029] Figure 5 for Figure 4 The flowchart of the manufacturing process of the functional module is shown below;

[0030] Figure 6 for Figure 4 The diagram shows the appearance of the functional module.

[0031] Figure 7 for Figure 4 The diagram shows the structure of the encapsulation layer fabricated using an injection mold in the manufacturing process of the functional module shown.

[0032] Figure 8 A schematic flowchart illustrating a method for preparing a functional module according to an embodiment of this application;

[0033] Figure 9 A process flow diagram for the fabrication of a functional module provided in this application embodiment;

[0034] Figure 10 For the corresponding Figure 9 Top view of each preparation process;

[0035] Figure 11 This is a schematic diagram of the structure of a flexible circuit board provided in an embodiment of this application;

[0036] Figure 12 This is a schematic diagram illustrating the structure during the cutting of the boss;

[0037] Figure 13 This is an example of the appearance of another functional module;

[0038] Figure 14 This is a schematic diagram of a panel structure for a functional module provided in an embodiment of this application;

[0039] Figure 15 This is a schematic diagram of the structure used in the fabrication of the reinforcing plate, provided in an embodiment of this application.

[0040] Figure 16 This is a structural schematic diagram of the process of peeling off the reinforcing plate according to an embodiment of this application;

[0041] Figure 17 This is a schematic diagram of the structure of a fingerprint recognition module provided in an embodiment of this application;

[0042] Figure 18 A process flow diagram for manufacturing a fingerprint recognition module provided in this application embodiment;

[0043] Figure 19 This is a schematic diagram of the structure of a capacitive detection module provided in an embodiment of this application;

[0044] Figure 20 This is a schematic diagram illustrating the structure and distribution of a capacitor structure as an example.

[0045] Figure 21 This application provides a flowchart of the manufacturing process of a capacitive detection module.

[0046] Figure 22 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0047] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0048] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0049] The terms "first" and "second," etc., used in the specification and claims of this application are used to distinguish different objects, not to describe a specific order of objects. For example, "first target object" and "second target object," etc., are used to distinguish different target objects, not to describe a specific order of target objects.

[0050] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0051] In the description of the embodiments in this application, unless otherwise stated, "multiple" means two or more. For example, multiple processing units means two or more processing units; multiple systems means two or more systems.

[0052] Figure 1 This is a structural diagram of a functional module. (Refer to...) Figure 1 As shown, the functional module includes a flexible printed circuit board (FPC) 10, a substrate (such as a printed circuit board, i.e., PCB) 20, a functional structure 30, and a molding compound 40. The functional structure 30 is located on the first surface of the substrate 20 in the thickness direction. The molding compound 40 (the molding compound 40 is the appearance part after the functional module is assembled into the electronic device; its shape can be referred to...) Figure 3 The functional structure 30 is covered to protect it. The second surface of the substrate 20 in the thickness direction (i.e. the surface of the substrate 20 opposite to the first surface) is provided with pads. The substrate 20 can be soldered to the flexible circuit board 10 to electrically connect the pads on the substrate 20 with the corresponding pads or pins on the flexible circuit board 10, thereby realizing signal transmission between the functional structure 30 and the flexible circuit board 10.

[0053] Figure 2 for Figure 1 The flowchart shows the manufacturing process of the functional module. (Refer to...) Figure 2 As shown, the method for preparing this functional module may include: referring to... Figure 2 In (a), a first substrate 20' is provided; refer to Figure 2 In (b), a functional structure 30 is formed on the first surface in the thickness direction of the first substrate 20'; refer to Figure 2 In step (c), an encapsulation layer 40' is formed on the first substrate 20' using an injection mold; refer to Figure 2 In step (d), according to the preset shape of the exterior component, the molding layer 40' and the first substrate 20' are cut simultaneously to obtain a molding component 40 and a substrate 20 with the same preset shape as the exterior component; refer to Figure 2 In step (e), the substrate 20 is soldered to the flexible circuit board 10 via pads on the second surface in the thickness direction. In this fabrication method, since the functional structure 30 is formed on the first substrate 20', the functional structure 30 is electrically connected to the flexible circuit board 10 through vias on the first substrate 20'. When cutting the molding compound 40' and the first substrate 20', there is no issue of cutting the signal lines between the functional structure 30 and the flexible circuit board 10. Therefore, the overall structure of the molding compound 40' and the first substrate 20' can be directly cut according to the preset shape of the appearance component, and then the cut substrate 20 is soldered to the flexible circuit board 10 to obtain the desired result. Figure 3 The shape shown is the same as the preset shape of the plastic seal 40.

[0054] It is understood that the similarities in this application are not absolute and completely identical, and the approximate similarities due to processing errors are also within the scope of similarities in this application.

[0055] Figure 4 This is a structural diagram of another functional module. (Refer to...) Figure 4 As shown, the functional module includes a flexible circuit board 10, a functional structure 30, and a molding compound 40. The functional structure 30 is located on the first surface of the flexible circuit board 10 along its thickness direction and is electrically connected to the flexible circuit board 10. The molding compound 40 covers the functional structure 30. This functional module saves space... Figure 1 The substrate 20 shown reduces the thickness of the functional module and lowers the cost of the substrate. At the same time, the welding process is eliminated, improving the overall reliability of the functional module.

[0056] Figure 5 for Figure 4 The flowchart shows the manufacturing process of the functional module. (Refer to...) Figure 5 As shown, the method for preparing this functional module may include: referring to... Figure 5 In (a), a flexible circuit board 10 is provided; refer to Figure 5In (b), a functional structure 30 is formed on the first surface of the flexible circuit board 10 in the thickness direction, and the functional structure 30 is electrically connected to the flexible circuit board 10; refer to Figure 5 In step (c), an encapsulation layer 40' is formed on the flexible circuit board 10 using an injection mold; refer to Figure 5 In step (d), the plastic sealant is cut according to the preset shape of the exterior part to obtain the following: Figure 6 The molding compound 40 and the boss 41 are shown. However, in this manufacturing method, the boss 41 is also formed by cutting the molding compound 40', and its thickness is the same as that of the molding compound 40. Furthermore, this boss is difficult to remove using cutting tools such as lasers or milling cutters. Therefore, when assembling the functional module prepared by this method, the molding compound 40 and the boss 41 can only be used together as the external components of the functional module. This increases the assembly difficulty of the functional module, and the assembled external components have additional features such as… Figure 6 The boss 41 shown reduces the appearance quality of the electronic device.

[0057] The reason for the above problem is: (Refer to...) Figure 7 As shown, after the injection mold is placed in the preset molding compound area (i.e., the area where the final molded compound 40 is located), there is a mold fit tolerance (0.05-0.3mm) between the injection mold and the preset molding compound area. After injection molding, a portion of the molding compound layer covers the wiring area (not shown in the figure) on the flexible circuit board 10 that is connected to the preset molding compound area. Lead wires are arranged on the wiring area for electrically connecting the terminals on the flexible circuit board 10 that are connected to the functional structure to the connectors on the flexible circuit board 10. Due to the presence of the lead wires on the flexible circuit board 10, if the molding compound layer is cut along the boundary of the preset molding compound area, the lead wires can easily be cut, causing the functional module to malfunction. Moreover, even if the molding compound layer is cut, because the molding compound layer is injection molded onto the flexible circuit board 10, the adhesive force between the molding compound layer and the flexible circuit board 10 is very strong, making it difficult to peel the boss off the flexible circuit board 10. Forcible peeling will also damage the flexible circuit board 10.

[0058] To solve such Figure 4 The functional modules shown in this application have problems such as difficulty in assembly and reduced appearance quality of electronic devices. This application provides a method for manufacturing a functional module, which can eliminate these problems. Figure 4 The diagram shows the bosses on the functional module. The fabrication method is described below with reference to the accompanying drawings.

[0059] For example, Figure 8 This is a flowchart illustrating a method for preparing a functional module according to an embodiment of this application. Figure 9 A process flow diagram for the fabrication of a functional module provided in this application embodiment; Figure 10 For the corresponding Figure 9Top view of each preparation process. (Refer to...) Figure 8 , Figure 9 and Figure 10 As shown, the method for preparing the functional module provided in this application includes the following steps:

[0060] S100, reference Figure 9 (a) and Figure 10 As shown in (a), a flexible circuit board 10 is provided. In this embodiment, the flexible circuit board 10 serves as the substrate of the functional module, supporting the functional structure 30 and the molding compound 40, and is electrically connected to the functional structure 30 to transmit the electrical signals sensed by the functional structure 30 to the motherboard of the electronic device. It is understood that lines matching the functional structure 30 can be pre-laid on the flexible circuit board 10 to mount the functional structure 30 on the flexible circuit board 10 and transmit the electrical signals of the functional structure 30.

[0061] This application does not limit the structure of the flexible circuit board 10. The flexible circuit board 10 can be a double-layer FPC structure or a multi-layer FPC structure. In one embodiment, the flexible circuit board 10 can adopt the following... Figure 11 The diagram shows a double-layer FPC structure. PI (polyimide) serves as the substrate of the flexible circuit board 10, providing support and insulation for the circuitry. Cu (copper oxide) acts as the conductive layer (i.e., the circuit layer) of the flexible circuit board 10, attached to the PI, and is typically formed from patterned copper foil. CVL (copper oxide layer) acts as a protective film layer of the flexible circuit board 10, located on the outermost layer, such as the first and last layers in the thickness direction of the flexible circuit board 10. Alternatively, when CVL is bonded to the conductive layer (Cu), it can be replaced by LPI (liquid polyimide). LPI covers areas that do not require soldering, preventing accidental connections (solder bridges) during soldering and avoiding short circuits and other faults. Simultaneously, LPI has excellent insulation properties, isolating different circuits and electronic components to prevent signal interference and leakage, ensuring the stable electrical performance of the flexible circuit board 10.

[0062] S200, reference Figure 9 (b) and Figure 10 As shown in (b), a functional structure 30 is formed on the first side of the flexible circuit board 10 in the thickness direction. The functional structure 30 is located in the preset molding compound area 101 (reference). Figure 9 (e) and Figure 10 In (a) of the above, the preset molding area 101 is the area where the appearance part of the functional module is located, and the pattern (including shape and size) of the preset molding area 101 is the same as the required pattern of the appearance part of the functional module. Therefore, by setting the functional structure 30 in the preset molding area 101, the functional structure 30 can sense the relevant operation performed by the user on the appearance part of the functional module, thereby realizing the corresponding function.

[0063] In this embodiment, the functional module can be a fingerprint recognition module or a capacitive detection module. Correspondingly, the functional structure 30 is a component provided to implement the functions related to the functional module (details are provided in the embodiments below).

[0064] It should be noted that forming the functional structure 30 on the first side in the thickness direction of the flexible circuit board 10 can be understood as: forming the functional structure 30 separately on the surface of the flexible circuit board 10, or forming the functional structure 30 using the film layer structure of the flexible circuit board 10 itself, with the functional structure 30 close to the first side of the flexible circuit board 10 (see the embodiments below for details). The specific configuration can be made according to actual needs.

[0065] S300, reference Figure 9 (c) and Figure 10 As shown in (c), a sacrificial layer 50 is formed on a first side of the flexible circuit board 10. The flexible circuit board 10 includes a lead-out area 102 connected to a pre-molded area 101 (lead wires of the lead-out area 102 are led out from the pre-molded area 101). The sacrificial layer 50 covers at least a portion of the lead-out area 102 and extends from the lead-out area 102 into the pre-molded area 101, and does not overlap with the functional structure 30.

[0066] S400, reference Figure 9 (d) and Figure 10 As shown in (d), a molding compound 40' is formed on the side of the functional structure 30 and the sacrificial layer 50 facing away from the flexible circuit board 10. The molding compound 40' covers the functional structure 30.

[0067] S500, reference Figure 9 (e) and Figure 10 As shown in (e), the molding layer 40' is cut in the thickness direction along the boundary of the preset molding area 101 connected to the wire exit area 102 (at the molding layer cutting line shown in the figure).

[0068] S600, reference Figure 9 (f) and Figure 10 As shown in (f), the sacrificial layer is peeled off to remove the molding layer on the functional module located outside the preset molding area, resulting in a molding 40 located in the preset molding area.

[0069] Based on S300, S400, S500, and S600, in this embodiment, the sacrificial layer 50 acts as a buffer when cutting the boss 41 to avoid cutting the flexible circuit board 10. Specifically, in the lead-out area 102, the sacrificial layer 50 at least covers a section of the lead-out area 102 near the preset molding compound area 101. For example, if the molding compound layer 40' is formed on the flexible circuit board 10 by injection molding using an injection mold, then in the lead-out area 102, the length of the sacrificial layer 50 along the direction of the lead wire extension (i.e., the direction from the preset molding compound area 101 to the lead-out area 102 at the connection between the preset molding compound area 101 and the lead-out area 102) is greater than or equal to the mold fit tolerance between the injection mold and the preset molding compound area 101. Therefore, in the thickness direction, the protrusion 41 formed by the molding compound 40' on the exit area 102 will be completely located on the sacrificial layer 50, meaning that no part of the molding compound 40' will be attached to the exit area 102, thus allowing the protrusion 41 to be completely removed as the sacrificial layer 50 is peeled off. Simultaneously, the sacrificial layer 50 extends from the exit area 102 into the predetermined molding compound area 101, thereby, when cutting the molding compound 40' along the boundary of the predetermined molding compound area 101 connected to the exit area 102, the cutting position (refer to...) Figure 9 (e) and Figure 10 The location of the molding layer cutting line shown in (e) is on the sacrificial layer 50, so that after cutting the molding layer 40', the cutting tool such as the laser or milling cutter can only cut into the sacrificial layer 50 at most, and cannot cut into the wire output area of ​​the flexible circuit board 10, thereby avoiding cutting the lead wire and realizing the non-destructive separation of the boss 41 and the molding 40.

[0070] In this embodiment, the sacrificial layer 50 should have a weak bond with the flexible circuit board 10 to facilitate its removal from the flexible circuit board 10. Considering the heating required for the subsequent molding process to form the encapsulation layer 40' and the potential subsequent welding processes, the sacrificial layer 50 should be made of a high-temperature resistant material. For example, the material of the sacrificial layer 50 may include, but is not limited to, at least one of PI, PET, and PEN. The thickness of the sacrificial layer 50 can be 12.5 μm to 50 μm, such as 12.5 μm, 25 μm, 50 μm, etc., to ensure that the sacrificial layer 50 can act as a buffer when cutting the boss 41, preventing damage to the lead wires on the flexible circuit board 10. Based on the above requirements for the sacrificial layer 50, in an optional embodiment, a 50 μm thick high-temperature tape is selected as the sacrificial layer 50. This allows the direct use of existing high-temperature tape as the sacrificial layer 50, reducing the difficulty of its preparation and improving processing efficiency.

[0071] When cutting bosses, due to machining errors, the actual cutting position may deviate from the molding layer cutting line. (Refer to...) Figure 12As shown, when the actual cutting position is located on the side of the molding layer cutting line facing the preset molding area 101, the actual cutting position may not overlap with the sacrificial layer 50 in the thickness direction of the flexible circuit board 10. In this case, the cutting equipment will not cut the sacrificial layer 50, resulting in the sacrificial layer 50 not playing a buffering role. Moreover, the part of the cut molding layer 40' connected to the boss is still attached to the flexible circuit board 10, and even if the sacrificial layer 50 is peeled off, the boss will not be removed. Therefore, in some embodiments of this application, the length of the sacrificial layer 50 extending from the junction of the lead-out area 102 and the preset molding area 101 to the preset molding area 101 is greater than the cutting error threshold. The cutting error threshold is the maximum value of the cutting deviation of the cutting equipment. This cutting error threshold can be determined according to the cutting accuracy of different cutting equipment. For example, when using laser cutting of the boss, the cutting error threshold can be 0.15mm. Thus, in the actual cutting process of the boss, it can be ensured that the sacrificial layer 50 plays a buffering role, and the boss is removed as the sacrificial layer 50 is peeled off.

[0072] Furthermore, if the sacrificial layer 50 overlaps with the functional structure 30, the overlapping portion of the functional structure 30 will be connected to the outside after the sacrificial layer 50 is peeled off, making the functional structure 50 susceptible to damage. Therefore, this embodiment ensures that the sacrificial layer 50 and the functional structure 30 do not overlap, allowing the formed molding compound 40 to completely cover the functional structure 50, thereby protecting the functional structure 50.

[0073] The boss is removed without cutting the lead wire. As described in S300, the sacrificial layer 50 should cover at least a portion of the exit area 102 and extend from the exit area 102 into the preset molding area 101. Therefore, in the exit area 102, the sacrificial layer 50 may cover only a section of the exit area 102 near the preset molding area 101, or the sacrificial layer 50 may cover the entire exit area 102.

[0074] Regarding the two scenarios described above, the sacrificial layer 50 can be disposed around the preset molding compound area 101, that is, a cutout portion is formed on the sacrificial layer 50, and this cutout portion is located in the preset molding compound area 101. Accordingly, refer to... Figure 10As shown in (c), in a preferred embodiment, the method for forming the sacrificial layer 50 on the first side of the flexible circuit board 10 may include: forming the sacrificial layer 50 over the entire first side of the flexible circuit board 10; forming a cutout portion 51 on the sacrificial layer 50, with the cutout portion 51 located within the preset molding compound area 101. Therefore, when using an injection mold for mold closing, the bottom circumference of the injection mold can be tightly fitted with the sacrificial layer 50, meaning the injection mold can more effectively enclose the preset molding compound area 101, thereby preventing leakage of the injection molding material. Furthermore, since the sacrificial layer 50 is laid over the entire surface of the flexible circuit board 10, any subsequent molding compound layers formed on the sacrificial layer 50 can be removed. Therefore, when closing the injection mold, there is no need to consider mold closing accuracy; simply placing the preset molding compound area 101 in the injection mold is sufficient, thus reducing operational difficulty. Additionally, to avoid the sacrificial layer 50 failing to provide a buffering effect due to cutting deviations, the length of the cutout portion 51 relative to the boundary of the preset molding compound area 101 is greater than the cutting error threshold mentioned above.

[0075] In this embodiment, the molding layer 40' is prepared using a molding process. Specifically, forming the molding layer 40' on the side of the functional structure 30 and the sacrificial layer 50 facing away from the flexible circuit board 10 includes: placing a preset molding component area 101 in an injection mold; injecting injection material into the mold; heating the injection material to a liquid state, and forming the molding layer 40' after cooling. The injection material may include epoxy molding compound (EMC), etc. The EMC is not specifically limited; for example, EMC may include resin and fillers dispersed in the resin. The resin may be any one or a combination of epoxy resin, silicone resin, silane-modified resin, silica resin, etc. The filler is not specifically limited; the filler may be granules; for example, the granules may be any one or a combination of SiO2, aluminum oxide (Al2O3), silicon nitride (Si3N4), boron nitride (BN), etc. In some embodiments, the filler size (diameter) is 5μm-55μm, and the EMC dielectric constant is 3-10. Preferably, the EMC type is A730E, the filler size is 55μm, the EMC dielectric constant is 7, and the EMC thickness is 250μm. This preferably uses a larger particle size for the EMC filler to reduce adhesive overflow in the product. The dielectric constant and thickness of the EMC, as well as the filler size, are not specifically limited and can be set according to actual conditions.

[0076] In this embodiment, a laser or a milling cutter can be used to cut the boss. The cutting depth into the sacrificial layer 50 can be controlled by controlling the laser energy or the milling cutter depth. There is no specific limitation on the cutting depth into the sacrificial layer 50; for example, it can be cut to half the thickness of the sacrificial layer 50. For example, using a laser to cut the boss, cutting the molding layer 40' along the boundary of the preset molding area 101 connected to the wire exit area 102 in the thickness direction includes: using a laser to cut the molding layer 40' along the boundary of the preset molding area 101 connected to the wire exit area 102 until the cutting depth in the sacrificial layer 50 reaches a preset depth, wherein the preset depth is less than the thickness of the sacrificial layer 50. In this way, by cutting into the sacrificial layer 50, it can be ensured that the boss is removed along with the sacrificial layer 50. Specifically, the thickness of the molding layer 40' is 250μm, the thickness of the sacrificial layer 50 is 50μm, the laser power is 20kW, the linear speed is 750mm / s, and the frequency is 100Hz. The line-filling method is to use the laser to cut along the above-mentioned boundary, and this is repeated 6 times to achieve a cutting depth of 25μm in the sacrificial layer 50.

[0077] It should be noted that a portion of the sacrificial layer 50 extends into the pre-molded area 101, and a portion of the sacrificial layer 50 is located on the side opposite to the lead-out area 102 at the actual cutting position. However, due to the weak adhesion between the sacrificial layer 50 and the flexible circuit board 10, this portion of the sacrificial layer 50 will be torn off along with the sacrificial layer 50 when it is peeled off. At this time, refer to... Figure 9 As shown in (f), a groove 42 is formed between the side end of the molding compound 40 and the flexible circuit board 10. The depth of the groove 42 is equal to the length of the sacrificial layer 50 extending from the actual cutting position to the preset molding compound area 101, and the length of the groove 42 in the thickness direction of the flexible circuit board 10 is equal to the thickness of the sacrificial layer 50. Of course, since the sacrificial layer 50 is relatively thin, the groove 42 formed on the molding compound 40 will not be exposed to the outside of the electronic device, and therefore will not affect the appearance quality of the electronic device.

[0078] It should be noted that when the area of ​​the flexible circuit board 10 is larger than the projected area of ​​the functional module on the flexible circuit board 10, refer to Figure 9 As shown in (e), it is necessary to follow the circuit board cut line (i.e. Figure 10The flexible circuit board 10 is cut along the outline of the preset module pattern 100 shown in (a) (if a sacrificial layer 50 and a molding layer 40' are provided at the corresponding position of the circuit board cutting line, they are also cut together) to obtain a functional module that meets the appearance design requirements. In this embodiment, the flexible circuit board 10 can be cut along the circuit board cutting line first, and then the molding layer 40' can be cut along the molding layer cutting line; or the molding layer 40' can be cut along the molding layer cutting line first, and then the flexible circuit board 10 can be cut along the circuit board cutting line. In addition, if a flexible circuit board 10 with a corresponding pattern is provided in advance according to the preset module pattern 100, then after the molding layer 40' is formed, it is not necessary to cut the flexible circuit board 10; it is only necessary to cut the molding layer 40' along the molding layer cutting line. It is understood that the preset module pattern 100 shown is only an illustrative example. The area covered by the preset module pattern 100 includes the preset molding area 101 and the outgoing line area 102, wherein the preset molding area 101 and the outgoing line area 102 are in a "T" shape. In another example, refer to Figure 13 As shown, the flexible circuit board 10 of the functional module can be an adapter board. The portion of the flexible circuit board 10 located in the outgoing area can be multiple segments, allowing the flexible circuit board 10 to bend against the housing of the electronic device and extend to the motherboard of the electronic device. A connector 11 is provided at the end of the outgoing area away from the preset plastic encapsulation area, and the flexible circuit board 10 is electrically connected to the motherboard through the connector 11.

[0079] Of course, the above-mentioned method for manufacturing functional modules can process multiple functional modules simultaneously. For example, refer to... Figure 14 As shown, a large-area flexible circuit board 10 (mother board) is provided, on which multiple functional modules are simultaneously fabricated. The flexible circuit board 10 is cut, and redundant boards are removed to form multiple independent functional modules. Therefore, multiple functional modules can be processed at once, thereby improving processing efficiency.

[0080] The method for fabricating a functional module provided in this application involves forming a sacrificial layer 50 on the surface of a flexible circuit board 10. This sacrificial layer 50 acts as a buffer during the cutting of the boss 41, allowing the boss 41 to be removed along with the peeling of the sacrificial layer 50. This method removes the boss without damaging the flexible circuit board, solving the problems of difficult assembly of functional modules and reduced appearance quality of electronic devices, thus improving the user experience.

[0081] Based on the above embodiments, referring to Figure 15 As shown, in some embodiments, after providing the flexible circuit board 10, a reinforcing plate 60 is further formed on a second side in the thickness direction of the flexible circuit board 10. Thus, the reinforcing plate 60 supports the flexible circuit board 10, ensuring that the flexible circuit board 10 remains flat, preventing sharp bends or breaks in the flexible circuit board 10, and improving the yield of component mounting and injection molding on the surface of the flexible circuit board 10.

[0082] Specifically, the reinforcing plate 60 is adhered to the surface of the second side of the flexible circuit board 10 via the adhesive layer 70. In the thickness direction of the flexible circuit board 10, the reinforcing plate 60 can overlap with the flexible circuit board 10, meaning the reinforcing plate 60 and the flexible circuit board 10 have the same shape and size. The reinforcing plate 60 can be made of Fr4 (a glass fiber reinforced epoxy resin composite material), stainless steel, glass, etc.; the thickness of the reinforcing plate 60 can be 100μm-200μm, or other thicknesses.

[0083] Considering that the presence of the reinforcing plate 60 increases the thickness of the functional module, therefore, referring to Figure 16 As shown, in some embodiments, after peeling off the sacrificial layer to remove the molding compound layer on the functional module located outside the preset molding compound area, the process further includes: peeling the reinforcing plate 60 off the flexible circuit board 10. This not only ensures the flatness of the functional structure and molding compound during the fabrication of the functional module, but also reduces the thickness of the functional module.

[0084] Specifically, to facilitate the peeling of the reinforcing plate 60 from the flexible circuit board 10, the adhesive layer 70 should be a temporary adhesive, i.e., an adhesive with weak adhesion to the flexible circuit board 10. This temporary adhesive can be a thermally degradable adhesive, a laser-reduced adhesive, or a chemically dissolved adhesive. Correspondingly, the material selection for the reinforcing plate 60 is related to the degrading process of the temporary adhesive. For example, if laser degrading is used, a transparent material (such as glass) should be selected for the reinforcing plate 60; if thermally degradable adhesive or a chemically dissolved adhesive is used, Fr4 or stainless steel materials can be selected for the reinforcing plate 60.

[0085] In one example, the adhesive layer 70 is a pyrolytic adhesive, and the reinforcing plate 60 is made of stainless steel. Pyrolytic bonding adhesive is printed on the surface of the reinforcing plate 60 to form the adhesive layer 70. The thickness of the pyrolytic bonding adhesive is 25μm-100μm, and the type can be BrewerBOND 305, ABLESTIK 8000, etc. The flexible circuit board 10 is pressed onto the surface of the reinforcing plate 60 with the adhesive layer 70 and cured at a temperature of 100℃-250℃. Thus, the reinforcing plate 60 is adhered to the flexible circuit board 10. For example, the pyrolytic bonding adhesive is BrewerBOND 305, with a thickness of 100μm and a curing temperature of 200℃. After peeling off the sacrificial layer, the functional module is heated to 150℃-300℃ and held for 5min-30min. A shear force of 0.1N-10N is applied between the flexible circuit board 10 and the reinforcing plate 60 to separate them. For example, the functional module is heated to 250°C, held for 10 minutes, and subjected to a shear force of 5N.

[0086] In some embodiments, the viscosity of the two sides of the adhesive layer 70 may be different. For example, the viscosity of the side of the adhesive layer 70 that is bonded to the reinforcing plate 60 is less than the viscosity of the side of the adhesive layer 70 that is bonded to the flexible circuit board 10. In this way, when the reinforcing plate 60 is peeled off, the adhesive layer 70 can remain on the reinforcing plate 60, thereby avoiding adhesive residue on the flexible circuit board 10, and enabling the reinforcing plate 60 and the adhesive layer 70 to be peeled off from the flexible circuit board 10 together.

[0087] Based on the above embodiments, the structure and preparation method of the functional modules, namely the fingerprint recognition module and the capacitive detection module, will be described below.

[0088] Example 1

[0089] Figure 17 This is a schematic diagram of a fingerprint recognition module provided in an embodiment of this application. (Refer to...) Figure 17 As shown, the functional structure of the fingerprint recognition module includes a fingerprint chip 31, which is fixed on the flexible circuit board 10 and electrically connected to the flexible circuit board 10. The functional layer of the fingerprint chip 31 is disposed away from the flexible circuit board 10.

[0090] In some embodiments, the fingerprint chip 31 can be bonded to the flexible circuit board 10 via an adhesion layer 32. Exemplarily, the material of the adhesion layer 32 includes die-attach film (DAF), silver paste, thermosetting adhesive, etc. For example, the material of the adhesion layer 32 includes DAF, and the film thickness before laminating the fingerprint chip 31 can be 100 μm. Alternatively, wire bonding can be used to achieve electrical connection between the fingerprint chip 31 and the flexible circuit board 10. Exemplarily, a gold wire with a diameter of 15 μm can be used as the bonding wire 33, through which the pads on the fingerprint chip 31 are electrically connected to the pads on the flexible circuit board 10.

[0091] The preparation method of the above fingerprint recognition module is described below.

[0092] Figure 18 This is a process flow diagram illustrating the fabrication process of a fingerprint recognition module provided in an embodiment of this application. (Refer to...) Figure 18 As shown, the fabrication method of this fingerprint recognition module includes the following steps:

[0093] Reference Figure 18 As shown in (a), a flexible circuit board 10 is provided. The flexible circuit board 10 has circuits and pads pre-set on it to match the fingerprint chip.

[0094] Reference Figure 18As shown in (b), a reinforcing plate 60 is formed on the second side of the flexible circuit board 10 in the thickness direction. The reinforcing plate 60 is bonded to the back side of the flexible circuit board 10, i.e., the side opposite to the fingerprint chip, by an adhesive layer 70. The adhesive layer 70 is a temporary adhesive to facilitate the subsequent peeling of the reinforcing plate 60 from the flexible circuit board.

[0095] Reference Figure 18 As shown in (c), the fingerprint chip 31 is fixed to the flexible circuit board 10. For example, adhesive is applied to the conductive layer of the flexible circuit board 10 to form an adhesion layer 32, and then the fingerprint chip 31 is placed on the adhesion layer 32 and pressed together, so that the fingerprint chip 31 is adhered to the flexible circuit board 10.

[0096] Reference Figure 18 As shown in (d), the fingerprint chip 31 is electrically connected to the flexible circuit board 10 using bonding wire 33. In one example, to further reduce the thickness of the fingerprint recognition module, a reverse gold wire bonding method can be used, that is, starting from the pads of the flexible circuit board 10, the gold wire is bonded to the pads on the surface of the fingerprint chip 31.

[0097] Reference Figure 18 As shown in (e), a sacrificial layer 50 is formed on a first side of the flexible circuit board 10 in the thickness direction, and a cutout is formed on the sacrificial layer 50. The cutout is located within a pre-defined molding compound area of ​​the flexible circuit board 10.

[0098] Reference Figure 18 As shown in (f), a molding compound 40' is formed on the side of the fingerprint chip 31 and the sacrificial layer 50 facing away from the flexible circuit board 10. The molding compound 40' covers the fingerprint chip 31 and the bonding wires 33. For example, the fingerprint chip 31 has a thickness of 600 μm, and the molding compound 40' includes an epoxy molding compound, specifically G700L, with a dielectric constant of 7. The epoxy molding compound includes resin and filler. To reduce the thickness of the molding compound 40', a filler size of 5 μm can be selected, in which case the thickness of the molding compound 40' can be 680 μm.

[0099] Reference Figure 18 As shown in (g), the molding layer 40' is cut along the molding layer cutting line in the thickness direction. Thus, the boss is separated from the molding component.

[0100] Reference Figure 18 As shown in (h), the sacrificial layer is peeled off to remove the molding layer on the fingerprint recognition module located outside the preset molding area, resulting in a molding 40 located in the preset molding area.

[0101] Reference Figure 18 As shown in (i), the reinforcing plate 60 is peeled off from the flexible circuit board 10. The fingerprint recognition module after peeling off the reinforcing plate 60 is as follows: Figure 17 As shown.

[0102] For details not described in the preparation method of the fingerprint recognition module provided in this embodiment, please refer to the preparation method of the functional module described above. They will not be repeated here.

[0103] Example 2

[0104] In this embodiment, the capacitive detection module includes multiple capacitance detection units, which are spaced apart along the length of the plastic package (the side button of the electronic device). When a user touches the plastic package, the corresponding capacitance detection unit detects the capacitance value; when the user does not touch the plastic package, none of the capacitance detection units detect a capacitance value. Therefore, when the user slides across the surface of the plastic package, the capacitance values ​​detected by the multiple capacitance detection units change systematically according to the arrangement of the units, with the changes in capacitance values ​​corresponding to up and down sliding operations being opposite. Thus, the capacitive detection module can determine the user's up and down sliding operations by identifying the changes in capacitance values ​​detected by each unit. Therefore, when the capacitive detection module is applied to an electronic device, it can replace the volume buttons or be shared with the power button to control functions such as volume, camera focus, and page turning.

[0105] In some embodiments, the capacitance detection unit includes a capacitor structure, which can be a mutual capacitance capacitor structure or a self-capacitive capacitor structure. The self-capacitive capacitor structure requires only one electrode; when the user touches the encapsulated component, the skin acts as a grounded counter electrode, and the capacitance value between the electrode and the skin can be detected. To reduce the thickness of the capacitance detection module, this embodiment employs a self-capacitive capacitor structure.

[0106] In a preferred embodiment, the Cu (conductive layer) in the flexible circuit board can be pre-patterned to form electrodes with a self-capacitive capacitor structure on the conductive layer, thereby further reducing the thickness of the capacitive detection module. This embodiment uses this self-capacitive capacitor structure as an example for illustration.

[0107] Figure 19 This is a schematic diagram of the structure of a capacitive detection module provided in an embodiment of this application. Figure 20 This is a schematic diagram illustrating the structure and distribution of a capacitor structure as an example. (Refer to...) Figure 19 and Figure 20As shown, the functional structure of this capacitive detection module includes multiple capacitor structures 34 spaced apart along the length of the molding compound. Each capacitor structure 34 includes electrodes located on the conductive layer (Cu) of the flexible circuit board 10. In this case, the CVL of the flexible circuit board 10 and the molding compound 40 act as the dielectric of the capacitor structure 34. The shape and size of the molding compound 40, and the shape and size of the capacitor structures 34 (or electrodes) are not specifically limited. For example, the molding compound 40 can be oval (composed of a rectangle and semicircles at both ends along its length), where the length l of the rectangle is 18.8 mm, the width w is 2 mm, and the radius of the semicircles is 1 mm. (Refer to...) Figure 20 As shown in (a), the capacitor structure 34 can be rectangular, with a length b equal to 2.26 mm, a width a equal to 1.8 mm, and a distance c between two adjacent capacitor structures 34 being 1.0 mm. (Refer to...) Figure 20 As shown in (b), the capacitor structure 34 can be arrow-shaped, where d equals 1.8 mm, e equals 4.5 mm, and f equals 1 mm.

[0108] The preparation method of the above-mentioned capacitive detection module is described below.

[0109] Figure 21 This is a process flow diagram illustrating the fabrication of a capacitive detection module provided in an embodiment of this application. (Refer to...) Figure 21 As shown, the fabrication method of this capacitive detection module includes the following steps:

[0110] Reference Figure 21 As shown in (a), a flexible circuit board 10 is provided. Multiple electrodes with capacitor structures are pre-formed in the conductive layer of the flexible circuit board 10, and the multiple electrodes are spaced apart along the length direction of a predetermined molding compound region.

[0111] Reference Figure 21 As shown in (b), a reinforcing plate 60 is formed on the second side of the flexible circuit board 10 in the thickness direction. The reinforcing plate 60 is bonded to the back of the flexible circuit board 10 by an adhesive layer 70. The adhesive layer 70 is a temporary adhesive to facilitate the subsequent peeling of the reinforcing plate 60 from the flexible circuit board.

[0112] Reference Figure 21 As shown in (c), a sacrificial layer 50 is formed on a first side of the flexible circuit board 10 in the thickness direction, and a cutout is formed on the sacrificial layer 50. The cutout is located within a pre-defined molding compound area of ​​the flexible circuit board 10.

[0113] Reference Figure 21As shown in (d), a molding compound 40' is formed on the side of the electrode and sacrificial layer 50 facing away from the flexible circuit board 10. The molding compound 40' covers the electrode. Exemplarily, the molding compound 40' comprises an epoxy molding compound, model A730E, with a dielectric constant of 7. The epoxy molding compound includes resin and filler. To reduce product overflow issues, a filler size of 55 μm can be selected.

[0114] Reference Figure 21 As shown in (e), the molding layer 40' is cut along the molding layer cutting line in the thickness direction. Thus, the boss is separated from the molding component.

[0115] Reference Figure 21 As shown in (f), the sacrificial layer is peeled off to remove the encapsulation layer on the capacitive detection module located outside the preset encapsulation area, resulting in an encapsulation 40 located in the preset encapsulation area.

[0116] Reference Figure 21 As shown in (g), the reinforcing plate 60 is peeled off from the flexible circuit board 10. The capacitive detection module after peeling off the reinforcing plate 60 is as follows: Figure 19 As shown.

[0117] For details not described in the preparation method of the capacitive detection module provided in this embodiment, please refer to the preparation method of the functional module described above. They will not be repeated here.

[0118] This application also provides an electronic device, which can be a terminal with side buttons, such as a mobile phone or a tablet computer. Figure 22 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application, with reference to... Figure 22 As shown, the electronic device 1 includes a housing 11, a motherboard 12, and a functional module from any of the above embodiments. The motherboard 12 and the flexible circuit board 10 of the functional module are placed inside the housing 11, and the flexible circuit board 10 is electrically connected to the motherboard. The housing 11 includes a middle frame, which includes an annular border 111. A mounting hole is provided on the border 111, and the plastic encapsulation 40 of the functional module passes through the mounting hole. The shape of the plastic encapsulation 40 is the same as the shape of the mounting hole, and can be rectangular, elliptical, oval, etc. The length and width dimensions of the plastic encapsulation 40 are slightly smaller than the dimensions of the mounting hole so that the plastic encapsulation 40 can pass through the mounting hole. The electronic device 1 may also include function keys such as a power button and volume buttons. The plastic encapsulation 40 may be set independently of the function keys, or it may share a key with the function keys.

[0119] In one example, the functional module is a fingerprint recognition module. The plastic molded component 40 can be shared with the power button (i.e., the plastic molded component 40 is reused as the power button) or with the volume buttons (i.e., the plastic molded component 40 is reused as the volume buttons). For example, when the plastic molded component 40 is shared with the power button, if the user touches the plastic molded component 40, functions such as screen unlocking and quick payment can be realized; if the user presses the plastic molded component 40, functions such as screen off, screen on, power off, and power on can be realized. When the plastic molded component 40 is shared with the volume buttons, if the user touches the plastic molded component 40, functions such as screen unlocking and quick payment can be realized; if the user presses the plastic molded component 40, functions such as volume adjustment, camera focus adjustment, and page turning can be realized.

[0120] In another example, the functional module is a capacitive detection module. The molding compound 40 can replace the existing volume buttons (i.e., the molding compound 40 is reused as volume buttons), and it can also combine the power button and volume buttons into one (i.e., the power button and volume buttons are integrated into the molding compound 40). For example, when the molding compound 40 replaces the press-type volume buttons, if the user slides on the surface of the molding compound 40, functions such as volume adjustment, camera focus adjustment, and page turning can be achieved. When the molding compound 40 combines the power button and volume buttons into one, if the user slides on the surface of the molding compound 40, functions such as volume adjustment, camera focus adjustment, and page turning can be achieved; if the user presses the molding compound 40, functions such as screen off, screen on, power off, and power on can be achieved.

[0121] Of course, electronic devices may also include both the fingerprint recognition module and the capacitive detection module described above. For example, the molding compound 40 of the fingerprint recognition module is shared with the power button, and the molding compound 40 of the capacitive detection module replaces the volume button.

[0122] In particular, electronic devices may also include camera control buttons. Pressing the camera control buttons can turn on the camera, take photos, select camera functions and settings, etc. Sliding on the camera control buttons can browse setting options, zoom in or out, increase or decrease exposure, increase or decrease background depth of field effects, increase or decrease color tone, etc.

[0123] In some embodiments, the functional module is a capacitive detection module, and the mounting holes include a first mounting hole, a second mounting hole, and a third mounting hole. The volume button passes through the first mounting hole, the power button passes through the second mounting hole, and the plastic seal of the capacitive detection module passes through the third mounting hole. The plastic seal serves as a camera control button.

[0124] In other embodiments, the functional module is a capacitive detection module, which includes a first capacitive detection module and a second capacitive detection module. The mounting holes include a first mounting hole and a second mounting hole. A first molding compound of the first capacitive detection module passes through the first mounting hole, and a second molding compound of the second capacitive detection module passes through the second mounting hole. The volume and power buttons are integrated into the first molding compound, and the second molding compound serves as a camera control button. This reduces the number of physical buttons while still providing a camera control button, improving the overall aesthetics and simplicity of the electronic device.

[0125] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing a functional module, characterized in that, include: Provide flexible circuit boards; A functional structure is formed on a first side in the thickness direction of the flexible circuit board, and the functional structure is located in a preset molding compound area; A sacrificial layer is formed on the first side of the flexible circuit board, the flexible circuit board including a trace area connected to the preset molding compound area, the sacrificial layer covering at least a portion of the trace area and extending from the trace area into the preset molding compound area; A molding compound is formed on the side of the functional structure and the sacrificial layer opposite to the flexible circuit board, and the molding compound covers the functional structure. Cut the molding layer in the thickness direction along the boundary of the preset molding area that is connected to the wire exit area; The sacrificial layer is peeled off to remove the molding layer on the functional module located outside the preset molding area.

2. The method for preparing the functional module according to claim 1, characterized in that, In the thickness direction of the flexible circuit board, the sacrificial layer does not overlap with the functional structure.

3. The method for preparing the functional module according to claim 1, characterized in that, The length of the sacrificial layer extending from the junction of the lead-out area and the preset molding area to the preset molding area is greater than the cutting error threshold.

4. The method for preparing the functional module according to claim 1, characterized in that, Forming a sacrificial layer on the first side of the flexible circuit board includes: A sacrificial layer is formed on the entire first side of the flexible circuit board; A cutout is formed on the sacrificial layer, and the cutout is located within the area of ​​the preset molding compound.

5. The method for preparing the functional module according to claim 4, characterized in that, The length of the recessed portion relative to the boundary of the preset molding area is greater than the cutting error threshold.

6. The method for preparing the functional module according to claim 1, characterized in that, The sacrificial layer is prepared using high-temperature adhesive tape.

7. The method for preparing the functional module according to claim 1, characterized in that, Cutting the molding layer in the thickness direction along the boundary of the preset molding area connected to the wire exit area includes: The molding layer is cut along the boundary of the preset molding area connected to the lead-out area until the cutting depth in the sacrificial layer reaches a preset depth, wherein the preset depth is less than the thickness of the sacrificial layer.

8. The method for preparing the functional module according to claim 1, characterized in that, After providing the flexible circuit board, the following are also included: A reinforcing plate is formed on the second side of the flexible circuit board in the thickness direction.

9. The method for preparing the functional module according to claim 8, characterized in that, After peeling off the sacrificial layer to remove the molding layer on the functional module located outside the preset molding area, the process further includes: The reinforcing plate is peeled off from the flexible circuit board.

10. The method for preparing the functional module according to claim 9, characterized in that, The reinforcing plate is attached to the flexible circuit board with an adhesive layer. The viscosity of the adhesive layer on the side bonded to the reinforcing plate is less than the viscosity of the adhesive layer on the side bonded to the flexible circuit board.

11. A functional module, manufactured using the method for manufacturing a functional module as described in any one of claims 1 to 10, characterized in that, The functional module includes: Flexible circuit board; A functional structure, wherein the functional structure is located on a first side in the thickness direction of the flexible circuit board; A molding compound that covers the functional structure, and a groove is formed between the side end of the molding compound and the flexible circuit board.

12. The functional module according to claim 11, characterized in that, The functional module is a fingerprint recognition module, and the functional structure includes a fingerprint chip, which is fixed on the flexible circuit board and electrically connected to the flexible circuit board.

13. The functional module according to claim 11, characterized in that, The functional module is a capacitive detection module. The functional structure includes multiple capacitor structures spaced apart along the length of the molding compound. Each capacitor structure includes an electrode located on the conductive layer of the flexible circuit board.

14. An electronic device, characterized in that, The device includes a housing and a functional module as described in any one of claims 11 to 13, wherein the housing includes a middle frame, the middle frame includes an annular border, the border has mounting holes, and the plastic encapsulation of the functional module passes through the mounting holes.

15. The electronic device according to claim 14, characterized in that, The electronic device also includes a motherboard, which is placed inside the housing, and the flexible circuit board of the functional module is electrically connected to the motherboard.

16. The electronic device according to claim 15, characterized in that, The flexible circuit board is an adapter board.

17. The electronic device according to claim 14, characterized in that, The electronic device also includes volume buttons and a power button, and the plastic encapsulation of the functional module is reused as either the volume button or the power button.

18. The electronic device according to claim 14, characterized in that, The functional module is a capacitive detection module, and the electronic device also includes volume buttons and a power button, which are integrated into the plastic encapsulation of the capacitive detection module.

19. The electronic device according to claim 14, characterized in that, The functional module is a capacitive detection module. The electronic device also includes volume buttons and a power button. The mounting holes include a first mounting hole, a second mounting hole, and a third mounting hole. The volume buttons pass through the first mounting hole, the power button passes through the second mounting hole, and the plastic seal of the capacitive detection module passes through the third mounting hole. The plastic seal serves as a camera control button.

20. The electronic device according to claim 14, characterized in that, The functional module is a capacitive detection module, which includes a first capacitive detection module and a second capacitive detection module. The electronic device also includes volume buttons and a power button. The mounting holes include a first mounting hole and a second mounting hole. A first molding compound of the first capacitive detection module passes through the first mounting hole, and a second molding compound of the second capacitive detection module passes through the second mounting hole. The volume buttons and the power button are integrated into the first molding compound, and the second molding compound serves as a camera control button.

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