Fingerprint module structure and preparation process thereof

Abstract

This application relates to a fingerprint module structure and its fabrication process. The fingerprint module structure includes: a flexible circuit board with a first pad forming a first electrode; a flexible film layer comprising a thin film layer, a metal layer, and a piezoelectric layer sequentially disposed thereon, the metal layer being disposed between the thin film layer and the piezoelectric layer, and the metal layer forming a second electrode; and a flexible conductive layer comprising a first conductive layer connected between the first pad and the piezoelectric layer to electrically connect the first electrode and the piezoelectric layer. By setting up the flexible circuit board, the flexible film layer, and the flexible conductive layer, the first pad on the flexible circuit board serves as the first electrode, the metal layer of the flexible film layer serves as the second electrode, the piezoelectric layer is disposed on the metal layer to achieve electrical connection, and the first conductive layer of the flexible conductive layer connects the first pad and the flexible film layer, and also achieves electrical connection between the piezoelectric layer and the first electrode. This makes the fingerprint module structure flexible and bendable, suitable for curved screens.

Description

Technical Field

[0001] This application relates to the field of fingerprint recognition technology, and in particular to the structure of fingerprint modules and their manufacturing process. Background Technology

[0002] With the development of the consumer electronics industry, especially the trend of mobile communication devices towards full-screen displays, ultrasonic fingerprint recognition has developed rapidly due to its faster recognition and safer use.

[0003] Currently, the mainstream ultrasonic solutions are mainly COF+TFT (glass substrate solution) and COF+Wafer (silicon wafer solution). The common feature of the two solutions is that they use a rigid substrate and drive the pixel electrodes designed on the TFT (glass substrate) or Wafer (silicon wafer), which makes it difficult to meet the needs of curved screens. Summary of the Invention

[0004] Therefore, it is necessary to provide a fingerprint module structure and its manufacturing process to address the problem that fingerprint module structures cannot meet the usage requirements of curved screens.

[0005] A fingerprint module structure, the fingerprint module structure comprising:

[0006] A flexible circuit board having a first pad, the first pad constituting a first electrode;

[0007] A flexible film layer includes a thin film layer, a metal layer and a piezoelectric layer arranged sequentially, wherein the metal layer is disposed between the thin film layer and the piezoelectric layer, and the metal layer constitutes a second electrode;

[0008] A flexible conductive layer includes a first conductive layer connected to the first pad and the piezoelectric layer to electrically connect the first electrode and the piezoelectric layer.

[0009] In one embodiment, the first conductive layer is configured as conductive double-sided adhesive.

[0010] In one embodiment, the flexible circuit board is provided with a second pad that is insulated from the first pad;

[0011] The flexible conductive layer further includes a second conductive layer, which is connected to the metal layer and to the second pad.

[0012] In one embodiment, a portion of the metal layer is exposed in the thickness direction of the flexible film layer, and the second conductive layer abuts against this portion of the metal layer;

[0013] And / or, the top surfaces of the first pad and the second pad are flush, and the thickness of the second conductive layer is equal to the sum of the thicknesses of the first conductive layer and the piezoelectric layer.

[0014] In one embodiment, the second conductive layer is configured as conductive double-sided adhesive;

[0015] And / or, the flexible circuit board is divided into a first pad area and a second pad area in a first direction, a first conductive layer is disposed in the first pad area, and a second conductive layer is disposed in the second pad area; or the flexible circuit board has a pad area where the first pad and the second pad are disposed, the first conductive layer covers the pad area, the first conductive layer has a clearance hole corresponding to the second pad, and the second conductive layer is located in the clearance hole.

[0016] In one embodiment, the fingerprint module structure further includes a chip disposed on the flexible circuit board, the chip being electrically connected to the first pad and the metal layer.

[0017] In one embodiment, multiple first pads are provided, and the multiple first pads constitute a pad array.

[0018] In one embodiment, the flexible circuit board is provided with an annular frame, an accommodating space is formed inside the annular frame, the first pad is located in the accommodating space, the first conductive layer is disposed in the accommodating space, and at least the piezoelectric layer of the flexible film is located in the accommodating space, or at least a portion of the piezoelectric layer is located in the accommodating space.

[0019] A fabrication process for the fingerprint module structure described above includes:

[0020] A flexible circuit board is provided, wherein a first pad is provided on the flexible circuit board, and the first pad constitutes a first electrode;

[0021] A flexible film layer is provided, the flexible film layer comprising a thin film layer, a metal layer and a piezoelectric layer, the metal layer being disposed on the thin film layer, the piezoelectric layer being disposed on the metal layer, and the metal layer constituting a second electrode;

[0022] A first conductive layer is provided and connected between the piezoelectric layer and the flexible circuit board, so that the piezoelectric layer and the second electrode are electrically connected.

[0023] In some embodiments, the method for preparing the flexible membrane layer includes:

[0024] Provide a thin film layer;

[0025] A metal layer is formed on the thin film layer;

[0026] A piezoelectric material is disposed on the metal layer and polarized to form the piezoelectric layer.

[0027] The aforementioned fingerprint module structure, by setting a flexible circuit board, a flexible film layer, and a flexible conductive layer, utilizes the first pad on the flexible circuit board as the first electrode, the metal layer of the flexible film layer as the second electrode, and the piezoelectric layer is disposed on the metal layer to achieve electrical connection. The first conductive layer of the flexible conductive layer connects the first pad and the flexible film layer, and also achieves electrical connection between the piezoelectric layer and the first electrode. In this way, the fingerprint module structure as a whole is flexible, bendable, and suitable for curved screens. Attached Figure Description

[0028] Figure 1 This is a top view of a flexible circuit board for a fingerprint module structure provided in some embodiments of this application.

[0029] Figure 2 This is a top view schematic diagram of the fingerprint module structure provided in some embodiments of this application.

[0030] Figure 3 for Figure 2 A cross-sectional view of the fingerprint module structure along direction AA.

[0031] Figure 4 for Figure 3 A magnified view of a portion of the image.

[0032] in:

[0033] 1. Flexible circuit board; 11. First pad; 12. Second pad; 13. Circular frame; 1a. Pad area; 1b. Component area.

[0034] 2. Flexible film layer; 21. Thin film layer; 22. Metal layer; 23. Piezoelectric layer.

[0035] 3. Flexible conductive layer; 31. First conductive layer; 32. Second conductive layer.

[0036] 4. Chip. Detailed Implementation

[0037] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0038] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0039] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0040] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0041] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0042] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0043] With the widespread adoption of full-screen technology in mobile terminals, under-display fingerprint recognition has become the mainstream biometric identification solution. Currently, the most widely used technologies in industrial applications are optical under-display fingerprint recognition and ultrasonic under-display fingerprint recognition. Among them, ultrasonic under-display fingerprint recognition technology has developed rapidly due to its faster recognition speed and more secure use.

[0044] The current mainstream ultrasonic solutions are mainly COF+TFT (glass substrate solution) and COF+Wafer (silicon wafer solution). The common feature of the two solutions is that they use a rigid substrate and drive the pixel electrodes designed on the TFT (glass substrate) or Wafer (silicon wafer). They are difficult to meet the needs of curved screens and require thinning after the entire process, which is complicated and has a long processing cycle.

[0045] Taking COF+TFT (glass substrate solution) as an example, the current process is TFT glass fabrication - coating piezoelectric electrodes and protective layers - thinning (outsourced to external manufacturers for processing or outsourced processing) - cutting - lamination with flexible board. Because it uses rigid glass, it is difficult to meet the application requirements of automotive curved screens and mobile phone curved screens. Moreover, the process cycle takes about 10-12 weeks. The process is complex, and the breakage rate is relatively high due to thinning and transportation.

[0046] To address the above issues, this application provides a fingerprint module structure that utilizes pads on a flexible circuit board as the first electrode, and forms a flexible film layer by creating a metal layer and a piezoelectric layer on a thin film layer. The metal layer serves as the second electrode, thus forming a flexible structure suitable for curved screens. Furthermore, it eliminates the need for outsourced thinning processes, simplifying the manufacturing process and shortening the processing cycle.

[0047] The specific processes include flexible circuit board production, flexible film layer fabrication, and lamination of the flexible film layer and flexible circuit board. The process cycle is approximately 5-6 weeks, which greatly shortens the processing time.

[0048] See Figures 1 to 3 , Figure 1 A top view schematic diagram of a flexible circuit board of a fingerprint module structure according to an embodiment of this application is shown. Figure 2 A top view schematic diagram of the fingerprint module structure in some embodiments of this application is shown. Figure 3 It shows Figure 2 A cross-sectional view of the fingerprint module structure along direction AA. Figure 4 for Figure 3 A magnified view of a portion of the image.

[0049] The fingerprint module structure provided in one embodiment of this application includes a flexible circuit board 1, a flexible film layer 2, and a flexible conductive layer 3.

[0050] Reference Figure 1 The flexible circuit board 1 has a first pad 11, which constitutes the first electrode. By using the pad on the flexible circuit board 1 as the first electrode, and taking advantage of the flexibility of the flexible circuit board 1 itself, it can be bent and is suitable for curved screens.

[0051] Flexible printed circuits (FPCs) offer advantages such as thinness, flexibility, and three-dimensional wiring. Currently, FPC pad processing mainly employs three categories: cover film windowing, solder resist ink windowing, and laser direct windowing / etching. These will not be elaborated upon further here.

[0052] The flexible circuit board 1 has multiple first pads 11, which together form a pad array. Each first pad 11 constitutes a pixel electrode. The pad array can be configured as follows: Figure 1 The rectangular array shown is an example. Of course, the number and arrangement of the first pads 11 can be set according to actual needs, such as an interlaced array, a ring (circular) array, etc.

[0053] It should be noted that a chip 4 is also disposed on the flexible circuit board 1. The chip 4 is electrically connected to the first pad 11, which is the first electrode, and the chip 4 is used to provide voltage to the first electrode. The chip 4 can be an ASIC (Application Specific Integrated Circuit) chip.

[0054] Reference Figures 2 to 4 The flexible film layer 2 includes a thin film layer 21, a metal layer 22 and a piezoelectric layer 23 arranged sequentially. The metal layer 22 is disposed between the thin film layer 21 and the piezoelectric layer 23, and the metal layer 22 constitutes the second electrode.

[0055] Reference Figure 3 and Figure 4 Along the direction close to the flexible circuit board 1, the thin film layer 21, the metal layer 22 and the piezoelectric layer 23 are arranged in sequence. That is, the piezoelectric layer 23 is closer to the flexible circuit board 1 than the metal layer 22, and the metal layer 22 is closer to the flexible circuit board 1 than the thin film layer 21.

[0056] Understandably, the thin film layer 21 serves as the substrate for forming the metal layer 22, and the metal layer 22 is formed directly on the thin film layer 21. The piezoelectric layer 23 is directly formed on the metal layer 22, thus achieving electrical connection between the second electrode and the piezoelectric layer 23. Moreover, the flexible film layer 2 is flexible and bendable as a whole, so it can be used with the flexible circuit board 1 to be suitable for curved screens.

[0057] The thin film layer 21 can be selected as a PI (Polyimide) film, a PET (Polyethylene Terephthalate) film, or other films, which will not be listed here.

[0058] In the preparation of the above-mentioned flexible film layer 2, a metal layer 22 is first formed on the thin film layer 21, then a piezoelectric material is placed on the metal layer 22, and then polarized to form a piezoelectric layer 23.

[0059] For example, the thickness of the metal layer 22 can be selected according to actual needs, such as 10 μm. The thickness of the piezoelectric layer 23 can be selected according to actual needs, such as 9 μm. In this way, the sum of the thicknesses of the thin film layer 21, the metal layer 22, and the piezoelectric layer 23 is small, which not only allows the flexible film layer 2 to be bent for use with curved screens, but also reduces the overall thickness of the fingerprint module structure in the thickness direction of the flexible film layer 2, thus achieving a thinner design for the fingerprint module structure.

[0060] The chip 4 is also electrically connected to the metal layer 22, which is the second electrode, to provide voltage to the second electrode, thereby creating a voltage difference between the second electrode and the first electrode, which in turn works with the piezoelectric layer 23 to achieve fingerprint recognition.

[0061] Reference Figure 3 and Figure 4 The flexible conductive layer 3 includes a first conductive layer 31, which is connected to the first pad 11 and the piezoelectric layer 23 to electrically connect the first electrode and the piezoelectric layer 23.

[0062] Understandably, the first conductive layer 31 not only serves to connect the first pad 11 and the flexible film layer 2, but also enables the first electrode and the piezoelectric layer 23 to be electrically connected. Thus, the metal layer 22 acts as the second electrode and is electrically connected to the piezoelectric layer 23, and the first pad 11 acts as the first electrode and is electrically connected to the piezoelectric layer 23 through the first conductive layer 31. This enables the fingerprint module structure to achieve its function.

[0063] The first conductive layer 31 is configured as a conductive double-sided adhesive. In this way, the first conductive layer 31 not only has the function of conducting electricity, but also bonds and connects the first solder pad 11 and the piezoelectric layer 23, that is, it realizes both electrical connection and mechanical fixation at the same time. This facilitates assembly, improves the connection stability between the flexible circuit board 1 and the flexible film layer 2, and the thickness is controllable, so that the fingerprint module structure can achieve a thinner design.

[0064] In addition, the use of conductive double-sided adhesive in the first conductive layer 31 is beneficial to the propagation of ultrasonic waves and reduces the attenuation of ultrasonic waves.

[0065] Of course, the first conductive layer 31 can also be configured to simultaneously connect the area of ​​the flexible circuit board 1 where the first solder pad 11 is not provided. In this case, the first conductive layer 31 also serves to connect the flexible circuit board 1 and the flexible film layer 2, which is beneficial to improving the overall connection stability of the fingerprint module structure.

[0066] The fingerprint module structure provided in some embodiments of this application, by setting a flexible circuit board 1, a flexible film layer 2 and a flexible conductive layer 3, uses the first pad 11 on the flexible circuit board 1 as the first electrode, the metal layer 22 of the flexible film layer 2 as the second electrode, and the piezoelectric layer 23 is disposed on the metal layer 22 to achieve electrical connection. The first conductive layer 31 of the flexible conductive layer 3 connects the first pad 11 and the flexible film layer 2, and achieves electrical connection between the piezoelectric layer 23 and the first electrode. In this way, the fingerprint module structure as a whole is flexible, bendable and suitable for curved screens.

[0067] Moreover, compared to the existing COF+TFT (glass substrate solution) and COF+Wafer (silicon-based wafer solution) technologies, this method eliminates the need for outsourced thinning, simplifying the process and significantly reducing the processing cycle. Furthermore, the piezoelectric layer 23 is disposed on the metal layer 22. During processing, after polarization, it is bonded to the first electrode via cutting and conductive double-sided adhesive. This mitigates the problem of the first electrode being easily damaged by high-voltage impacts on the piezoelectric layer 23 during polarization.

[0068] In some embodiments, refer to Figure 1 , Figure 3 and Figure 4 The flexible circuit board 1 has a second pad 12 that is insulated from the first pad 11. The flexible conductive layer 3 also includes a second conductive layer 32, which is connected to the metal layer 22 and to the second pad 12.

[0069] Understandably, the metal layer 22 and the second pad 12 are connected and electrically conductive through the second conductive layer 32, achieving electrical conductivity while connecting the two structures, thus improving the stability of the structure.

[0070] The second conductive layer 32 is configured as a conductive double-sided adhesive, which not only has a conductive function, but also bonds and connects the flexible circuit board 1 and the metal layer 22. That is, it simultaneously achieves electrical connection and mechanical fixation, which facilitates assembly, improves the connection stability between the flexible circuit board 1 and the flexible film layer 2, and the thickness is controllable.

[0071] In addition, the use of conductive double-sided adhesive in the second conductive layer 32 is beneficial to the propagation of ultrasonic waves and reduces the attenuation of ultrasonic waves.

[0072] Reference Figure 3 and Figure 4 In the thickness direction of the flexible film layer 2, a portion of the metal layer 22 is exposed, and the second conductive layer 32 abuts against this portion of the metal layer 22.

[0073] Understandably, the second conductive layer 32 supports the flexible film layer 2 in the thickness direction of the flexible film layer 2 and is electrically connected to the metal layer 22, thereby realizing the electrical connection between the metal layer 22 and the second pad 12. In this way, the second conductive layer 32 and the first conductive layer 31 simultaneously play the role of supporting the flexible film layer 2, which helps to make the flexible film layer 2 flat as a whole.

[0074] In one specific implementation, the area of ​​the piezoelectric layer 23 is smaller than the area of ​​the metal layer 22. In this case, the piezoelectric layer 23 does not cover the entire metal layer 22, and the piezoelectric layer 23 is located on one side of the second conductive layer 32.

[0075] In another specific implementation, the piezoelectric layer has a clearance notch that exposes the metal layer, and the second conductive layer extends into the clearance notch, with the piezoelectric layer surrounding the second conductive layer. That is, the edge of the piezoelectric layer covers the edge of the metal layer, and a clearance design is implemented to allow the metal layer and the second pad to connect through the second conductive layer.

[0076] It should be noted that the gap between the piezoelectric layer 23 and the second conductive layer 32 is designed to meet insulation requirements, thereby achieving insulation between the piezoelectric layer 23 and the second conductive layer 32. Alternatively, an insulating layer or insulating adhesive may be provided between the piezoelectric layer 23 and the second conductive layer 32 to achieve insulation.

[0077] Reference Figure 3 and Figure 4 In one specific implementation, the top surfaces of the first pad 11 and the second pad 12 are flush, and the sum of the thicknesses of the piezoelectric layer 23 and the first conductive layer 31 is equal to the thickness of the second conductive layer 32. Thus, relative to the flexible circuit board 1, the flexible film layer 2 is supported by both the first conductive layer 31 and the second conductive layer 32, making the flexible film layer 2 generally horizontal or in a horizontal state, without obvious steps or warping, which is beneficial for improving acoustic performance, electrical uniformity, and reliability.

[0078] For example, the thickness of the piezoelectric layer 23 is 9 μm, the thickness of the first conductive layer 31 is 15 μm, and the thickness of the second conductive layer 32 is 24 μm. Of course, the thicknesses of the piezoelectric layer 23, the first conductive layer 31, and the second conductive layer 32 can be set according to actual needs.

[0079] Of course, in another specific implementation, the top surfaces of the first pad and the second pad may not be flush. In this case, by setting the thickness of the piezoelectric layer, the first conductive layer and the second conductive layer, the top surface of the first conductive layer is in contact with the piezoelectric layer and the second conductive layer is in contact with the metal layer, so that the flexible film layer as a whole tends to be horizontal or in a horizontal state, without obvious steps or warping.

[0080] Reference Figure 3 and Figure 4 In one specific implementation, the pad area of ​​the flexible circuit board 1 is divided into a first pad area and a second pad area in a first direction. A first conductive layer 31 is disposed in the first pad area, and a second conductive layer 32 is disposed in the second pad area, where both support the flexible film layer 2. The first conductive layer 31 and the second conductive layer 32 are spaced apart in a first direction, which is the width or length direction of the pad area. Specifically, a first pad 11 is disposed in the first pad area, and a second pad 12 is disposed in the second pad area.

[0081] In another specific implementation, the flexible circuit board may have a pad area with a first pad and a second pad, a first conductive layer covering the pad area, a clearance hole being formed in the first conductive layer corresponding to the second pad, and the second conductive layer being located inside the clearance hole.

[0082] Understandably, the first conductive layer surrounds the second conductive layer, covering the pad area, thus allowing most of the flexible film layer to be supported by the first conductive layer. In this case, the area of ​​the second conductive layer can be set relatively small, allowing the first conductive layer to play the main supporting role, while the second conductive layer mainly plays the role of electrical conduction.

[0083] It should be noted that the insulation between the first conductive layer 31 and the second conductive layer 32 can be achieved by setting a gap between them, or an insulating layer can be set between the first conductive layer 31 and the second conductive layer 32 to achieve insulation.

[0084] Reference Figure 1 and Figure 2 In some embodiments, the fingerprint module structure further includes a chip 4, which is disposed on the flexible circuit board 1 and electrically connected to the first pad 11 and the metal layer 22.

[0085] Understandably, chip 4 is electrically connected to the first pad 11, which is the first electrode, and chip 4 is used to provide voltage to the first electrode. Chip 4 is also electrically connected to the metal layer 22, which is the second electrode, and is used to provide voltage to the second electrode. This creates a voltage difference between the second electrode and the first electrode, thereby enabling the fingerprint module structure to achieve the function of fingerprint recognition.

[0086] In this configuration, chip 4 and metal layer 22 are electrically connected through second pad 12 and second conductive layer 32. Specifically, second pad 12 and chip 4 are electrically connected.

[0087] Specifically, the metal layer 22 constitutes the upper electrode, and the first pad 11 constitutes the lower electrode. When the system of a device using this fingerprint module structure sends a command to the fingerprint module structure to identify a fingerprint, the chip 4 outputs a high-frequency voltage to the second electrode and simultaneously outputs a reference voltage to the first electrode, creating a voltage difference between the second and first electrodes. The piezoelectric layer 23 deforms to generate ultrasonic waves, which return sequentially according to the different heights of the finger's concave and convex positions. The chip 4 outputs a reference voltage to the second electrode. At this time, the piezoelectric layer 23 receives the ultrasonic waves and converts the deformation into a voltage difference, which is distributed across each of the first pads 11. The chip 4 reads the voltage of each first pad 11, processes it, converts it into a grayscale signal, and transmits the grayscale signal back to the system for comparison and confirmation.

[0088] It should be noted that the chip 4, the first pad 11 and the second pad 12 can be set in separate areas. For example, the chip 4 can be set in the component area 1b on the flexible circuit board 1, while the first pad 11 and the second pad 12 can be set in the pad area 1a on the flexible circuit board 1.

[0089] The pad area 1a and component area 1b are separated, meaning they are distinct and do not overlap. Functionally, component area 1b houses electronic components such as resistors, capacitors, semiconductor devices, and integrated circuits, forming the core area for signal processing and circuit driving. Pad area 1a has a first pad 11 and a second pad 12, serving as the interface between the flexible film layer 2 and the flexible conductive layer 3. Electrically, pad area 1a and component area 1b are not directly connected; instead, they are connected by a wiring harness to form an electrical circuit, enabling cross-regional transmission of electrical signals and power, thus creating a complete circuit system.

[0090] Thus, the separate design of pad area 1a and component area 1b facilitates separate component mounting during the production stage, avoiding cross-process interference and improving production yield and processing efficiency. It also achieves signal isolation, reduces electromagnetic crosstalk, and streamlines the circuit layout, further improving production yield. Furthermore, it isolates the stress on different areas, optimizes mechanical distribution, and enhances the overall reliability of the flexible circuit board 1.

[0091] In addition, the bending areas can be planned in a targeted manner so that both component area 1b and pad area 1a avoid bending sections, reducing the risk of electronic components and pads falling off due to bending. Moreover, the partitioned design also facilitates later inspection and maintenance.

[0092] Reference Figure 3 and Figure 4 In some embodiments, the flexible circuit board 1 is provided with an annular frame 13, and an accommodating space is formed inside the annular frame 13. The first pad 11 is located in the accommodating space, the flexible conductive layer 3 is disposed in the accommodating space, and at least the piezoelectric layer 23 of the flexible film layer 2 is located in the accommodating space. Alternatively, at least a portion of the piezoelectric layer 23 may be located in the accommodating space. The second pad 12 is also located in the accommodating space.

[0093] Understandably, the annular frame 13 serves as a support, and by limiting the flexible conductive layer 3 and the flexible film layer 2, it can optimize the warpage of the region to some extent.

[0094] The annular frame 13 is a metal frame. Of course, when the flexible circuit board 1 needs to be fully flexible, the annular frame 13 can be removed, thereby increasing the flexibility of the flexible circuit board 1 in the area where the first pad 11 and the second pad 12 are located.

[0095] For example, refer to Figures 1 to 4 A fingerprint module structure is presented, including a flexible circuit board 1, a flexible film layer 2, and a flexible conductive layer 3.

[0096] The flexible circuit board 1 has a first pad 11 and a second pad 12. The first pad 11 constitutes a first electrode. There are multiple first pads 11 arranged in an array, and each first pad 11 constitutes a pixel electrode.

[0097] The flexible film layer 2 includes a thin film layer 21, a metal layer 22 and a piezoelectric layer 23. The metal layer 22 is disposed on the thin film layer 21, and the piezoelectric layer 23 is disposed on the metal layer 22. The metal layer 22 constitutes the second electrode.

[0098] The flexible conductive layer 3 includes a first conductive layer 31 and a second conductive layer 32, both of which are selected as conductive double-sided adhesive.

[0099] In this design, the first conductive layer 31 bonds the flexible circuit board 1 and the piezoelectric layer 23, achieving an electrical connection between the piezoelectric layer 23 and the first electrode. The second conductive layer 32 bonds the flexible circuit board 1 and the metal layer 22, achieving an electrical connection between the metal layer 22 and the second pad 12. At this point, the piezoelectric layer 23 does not cover the entire metal layer 22; a portion of the metal layer 22 is exposed in the thickness direction of the flexible film layer 2 to contact the second conductive layer 32.

[0100] Some embodiments of this application also provide a fabrication process for a fingerprint module structure, including:

[0101] A flexible circuit board 1 is provided, on which a first pad 11 is disposed, the first pad 11 constituting a first electrode. There are multiple first pads 11, which are arranged in an array, and each first pad 11 constitutes a pixel electrode.

[0102] A flexible film layer 2 is provided, which includes a thin film layer 21, a metal layer 22 and a piezoelectric layer 23. The metal layer 22 is disposed on the thin film layer 21, and the piezoelectric layer 23 is disposed on the metal layer 22. The metal layer 22 constitutes a second electrode.

[0103] A first conductive layer 31 is provided and connected between the piezoelectric layer 23 and the flexible circuit board 1, so that the piezoelectric layer 23 and the first pad 11 are electrically connected.

[0104] The manufacturing process of this fingerprint module utilizes the first pad 11 on the flexible circuit board 1 as the first electrode, the metal layer 22 of the flexible film layer 2 as the second electrode, and the piezoelectric layer 23 disposed on the metal layer 22 to achieve electrical connection. The first conductive layer 31 connects the flexible circuit board 1 and the flexible film layer 2, and achieves electrical connection between the piezoelectric layer 23 and the first electrode. In this way, the fingerprint module structure as a whole is flexible, can be bent and is suitable for curved screens.

[0105] Furthermore, the manufacturing process of this fingerprint module structure can be summarized as follows: production of flexible circuit board 1, fabrication of flexible film layer 2, and bonding of flexible film layer 2 and flexible circuit board 1 (by bonding through first conductive layer 31). The process cycle is approximately 5-6 weeks, eliminating the need for outsourced thinning and significantly shortening the processing cycle.

[0106] Currently, the processing of FPC pads mainly adopts three categories: cover film windowing process, solder resist ink windowing process, and laser direct windowing / etching process, which will not be elaborated on here.

[0107] Furthermore, a second pad 12 is provided on the flexible circuit board 1, and a portion of the metal layer 22 is exposed in the thickness direction of the flexible film layer 2. The fabrication process also includes:

[0108] A second conductive layer 32 is provided and connected to the metal layer 22 and the second pad 12.

[0109] Furthermore, the method for preparing the above-mentioned flexible membrane layer 2 includes:

[0110] Provide a thin film layer 21;

[0111] A metal layer 22 is formed on the thin film layer 21;

[0112] A piezoelectric material is disposed on the metal layer 22 and polarized to form a piezoelectric layer 23.

[0113] Thus, in the fabrication process of this fingerprint module structure, after polarizing the piezoelectric layer 23, the flexible film layer 2 and the flexible circuit board 1 are connected through the first conductive layer 31 and the second conductive layer 32, which can improve the problem that the piezoelectric layer 23 is easily damaged by high voltage during the polarization process and thus easily damages the first electrode.

[0114] The metal layer 22 formed on the thin film layer 21 can be formed by physical vapor deposition, electroplating, or other processes. No specific limitations are made here, and the appropriate process can be selected according to actual needs.

[0115] The piezoelectric material can be deposited on the metal layer 22 using processes such as physical vapor deposition, chemical vapor deposition, or coating. No specific restrictions are imposed here, and the appropriate method can be selected according to actual needs.

[0116] In simple terms, polarization is to give piezoelectric materials "piezoelectric ability". The commonly used method is high-voltage electric field polarization, which will not be elaborated on here.

[0117] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0118] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A fingerprint module structure, characterized in that, The fingerprint module structure includes: A flexible circuit board (1) is provided with a first pad (11), the first pad (11) forming a first electrode; The flexible film layer (2) includes a thin film layer (21), a metal layer (22) and a piezoelectric layer (23) arranged sequentially. The metal layer (22) is disposed between the thin film layer (21) and the piezoelectric layer (23), and the metal layer (22) constitutes a second electrode. The flexible conductive layer (3) includes a first conductive layer (31) which is connected to the first pad (11) and the piezoelectric layer (23) to electrically connect the first electrode and the piezoelectric layer (23).

2. The fingerprint module structure according to claim 1, characterized in that, The first conductive layer (31) is configured as a conductive double-sided adhesive.

3. The fingerprint module structure according to claim 1, characterized in that, The flexible circuit board (1) is provided with a second pad (12) that is insulated from the first pad (11). The flexible conductive layer (3) further includes a second conductive layer (32), which is connected to the metal layer (22) and to the second pad (12).

4. The fingerprint module structure according to claim 3, characterized in that, In the thickness direction of the flexible film layer (2), a portion of the metal layer (22) is exposed, and the second conductive layer (32) abuts against this portion of the metal layer (22). And / or, the top surfaces of the first pad (11) and the second pad (12) are flush, and the thickness of the second conductive layer (32) is equal to the sum of the thicknesses of the first conductive layer (31) and the piezoelectric layer (23).

5. The fingerprint module structure according to claim 3, characterized in that, The second conductive layer (32) is configured as a conductive double-sided adhesive; And / or, the flexible circuit board (1) is divided into a first pad area and a second pad area in a first direction, a first conductive layer (31) is disposed in the first pad area, and a second conductive layer (32) is disposed in the second pad area; or the flexible circuit board (1) has a pad area where the first pad (11) and the second pad (12) are disposed, the first conductive layer (31) covers the pad area, the first conductive layer (31) has a clearance hole corresponding to the second pad (12), and the second conductive layer (32) is located in the clearance hole.

6. The fingerprint module structure according to claim 1, characterized in that, The fingerprint module structure also includes a chip (4), which is disposed on the flexible circuit board (1) and electrically connected to the first pad (11) and the metal layer (22).

7. The fingerprint module structure according to claim 1, characterized in that, The first pad (11) is provided in multiple ways, and the multiple first pads (11) constitute a pad array.

8. The fingerprint module structure according to claim 1, characterized in that, The flexible circuit board (1) is provided with an annular frame (13), and an accommodating space is formed inside the annular frame (13). The first pad (11) is located in the accommodating space, the first conductive layer (31) is disposed in the accommodating space, and at least the piezoelectric layer (23) of the flexible film layer (2) is located in the accommodating space, or at least a portion of the piezoelectric layer (23) is located in the accommodating space.

9. A fabrication process for a fingerprint module structure as described in any one of claims 1-8, characterized in that, include: A flexible circuit board (1) is provided, wherein a first pad (11) is provided on the flexible circuit board (1), and the first pad (11) constitutes a first electrode; A flexible film layer (2) is provided, the flexible film layer (2) including a thin film layer (21), a metal layer (22) and a piezoelectric layer (23), the metal layer (22) being disposed on the thin film layer (21), the piezoelectric layer (23) being disposed on the metal layer (22), and the metal layer (22) constituting a second electrode; A first conductive layer (31) is provided and connected between the piezoelectric layer (23) and the flexible circuit board (1) so that the piezoelectric layer (23) and the second electrode are electrically connected.

10. The fabrication process of the fingerprint module structure according to claim 9, characterized in that, The method for preparing the flexible film layer (2) includes: Provide a thin film layer (21); A metal layer (22) is formed on the thin film layer (21); A piezoelectric material is disposed on the metal layer (22) and the piezoelectric layer (23) is formed by polarization.

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