WO2023230866A1

WO2023230866A1 - Ultrasonic fingerprint recognition apparatus and electronic device

Info

Publication number: WO2023230866A1
Application number: PCT/CN2022/096318
Authority: WO
Inventors: 龙卫
Original assignee: 深圳市汇顶科技股份有限公司
Priority date: 2022-05-31
Filing date: 2022-05-31
Publication date: 2023-12-07

Abstract

The present application provides an ultrasonic fingerprint recognition apparatus and an electronic device, which have good performance. The ultrasonic fingerprint recognition apparatus is arranged under a display screen to realize under-screen ultrasonic fingerprint recognition, and the ultrasonic fingerprint recognition apparatus comprises: an ultrasonic detection chip, which is bonded to the display screen, wherein a piezoelectric material layer and a metal wiring layer are provided on the side of the ultrasonic detection chip that is away from the display screen, and the piezoelectric material layer is used for transmitting an ultrasonic signal to a finger over the display screen and receiving an ultrasonic detection signal which is returned by the finger, the ultrasonic detection signal being used by the ultrasonic detection chip for acquiring fingerprint information of the finger; and an FPC, which is arranged on the side of the ultrasonic detection chip that is away from the display screen, wherein a pad of the FPC and a pad of the metal wiring layer are laminated by means of an ACF, so as to realize the interconnection between the ultrasonic detection chip and the FPC.

Description

Ultrasonic fingerprint recognition devices and electronic equipment

Technical field

Embodiments of the present application relate to the field of fingerprint identification, and more specifically, to an ultrasonic fingerprint identification device and electronic equipment.

Background technique

With the progress of society, mobile phones have become one of the essential electronic devices in modern life. Currently, mobile phones on the market have one or more identity authentication methods, including digital passwords, gesture graphics, facial recognition, fingerprint recognition, etc. Among them, fingerprint recognition has become a standard feature of most mobile phones due to its convenient application, fast recognition speed, stability and reliability. Fingerprint recognition has also developed different technical routes, including capacitive fingerprint recognition, optical fingerprint recognition and ultrasonic fingerprint recognition.

Ultrasonic fingerprint recognition can not only identify the surface morphology of fingerprints, but also identify signals from the dermal layer of the finger, thereby achieving natural 3D anti-counterfeiting. Compared with optical fingerprint recognition, ultrasonic fingerprint recognition has a higher impact on the cleanliness of the finger surface. Tolerance. Therefore, ultrasonic fingerprint recognition has gradually become a new generation of fingerprint recognition method. How to improve the packaging structure of the ultrasonic fingerprint recognition device to enhance its performance has become a problem that needs to be solved.

Contents of the invention

Embodiments of the present application provide an ultrasonic fingerprint identification device and electronic equipment, which have good performance.

In a first aspect, an ultrasonic fingerprint identification device is provided, which is disposed under a display screen of an electronic device to realize under-screen ultrasonic fingerprint identification. The ultrasonic fingerprint identification device includes: an ultrasonic detection chip, and the ultrasonic detection chip and the The display screen is bonded. The side of the ultrasonic detection chip away from the display screen is provided with a piezoelectric material layer and a metal wiring layer. The piezoelectric material layer is used to emit ultrasonic signals to the fingers above the display screen, and Receive the ultrasonic detection signal returned by the finger, and the ultrasonic detection signal is used by the ultrasonic detection chip to obtain the fingerprint information of the finger; and, a flexible circuit board, the flexible circuit board is arranged away from the ultrasonic detection chip. On one side of the display screen, the pads of the flexible circuit board and the pads of the metal wiring layer are pressed together through an anisotropic conductive adhesive film to realize the connection between the ultrasonic detection chip and the flexible circuit board. interconnected.

In the embodiment of the present application, the ultrasonic fingerprint identification device is attached to the lower surface of the display screen in a back-attached manner. Contrary to the front-attached method, the ultrasonic detection chip in the ultrasonic fingerprint identification device is placed close to the display screen and the piezoelectric material is far away from the display screen. screen settings. The ultrasonic fingerprint recognition device includes an ultrasonic detection chip. One side of the ultrasonic detection chip is directly bonded to the lower surface of the display screen, and the other side is a piezoelectric material layer and a metal wiring layer. Since the ultrasonic detection chip is bonded to the display screen, it has a certain strength and a large bonding area, thus reducing the warpage caused by the bonding of the ultrasonic fingerprint recognition device to the display screen and making it less likely to appear on the display screen. Appearance imprint. Since the ultrasonic detection signal returned by the finger passes through the piezoelectric material layer and reaches the air interface, it can be fully reflected back. In addition, the encapsulated stacked structure is relatively simple, thus reducing signal loss and improving the fingerprint recognition of the ultrasonic fingerprint recognition device. performance.

In one implementation, the metal wiring layer is a rewiring layer, and the pads of the flexible circuit board and the pads of the rewiring layer are pressed together through the anisotropic conductive adhesive film to achieve the above Ultrasonic detection of the interconnection between the chip and the flexible circuit board. New pads are formed on the surface of the fingerprint recognition chip through rewiring to facilitate the electrical connection between the flexible circuit board and the ultrasonic detection chip.

In one implementation, the edge of the ultrasonic detection chip is provided with a step recessed toward the display screen, and the rewiring layer is provided within the step to form a step for connecting the flexible Circuit board pads. The depth of the steps may be less than or equal to 100um, for example.

By setting steps and forming pads within the steps through rewiring, the lamination surface between the pads of the flexible circuit board and the pads of the rewiring layer is located within the steps, thereby reducing the height of the flexible circuit board, thereby reducing the height of the flexible circuit board. The overall thickness of the ultrasonic fingerprint recognition device is reduced and the internal space of the electronic device is saved.

In one implementation, the thickness of the piezoelectric material layer is less than or equal to 50um; or, the piezoelectric material layer is farther away from the surface of the ultrasonic detection chip than the flexible circuit board is farther away from the ultrasonic detection chip. The surface of the chip, closer to the display. While meeting the needs of ultrasonic transmission and reception, it reduces the overall thickness of the ultrasonic fingerprint recognition device and saves the internal space of the electronic device.

In one implementation, the ultrasonic detection chip and the display screen are bonded through a glue film, the thickness of the glue film is less than or equal to 50um, and/or the acoustic resistance coefficient of the glue film is greater than or equal to 4. For example, the adhesive film is a chip bonding film or epoxy resin, thereby ensuring good bonding ability without increasing the thickness of the module and reducing the impact on signal transmission.

In one implementation, the piezoelectric material layer is provided with a first electrode on its surface close to the ultrasonic detection chip, and a second electrode is provided on its surface far away from the ultrasonic detection chip. The second electrode is made of a plurality of An electrode array composed of three electrodes, the first electrode and the second electrode are electrically connected to the ultrasonic detection chip.

In one implementation, the piezoelectric material layer is formed of at least one of the following materials: polyvinylidene fluoride, polyvinylidene fluoride-trifluoroethylene copolymer, barium titanate series, lead zirconate titanate Binary system and adding a third ABO3 type compound to the binary system, where A represents a divalent metal ion, B represents a tetravalent metal ion or the sum of several ions is positive tetravalent.

In a second aspect, an electronic device is provided, including: a display screen; and an ultrasonic fingerprint recognition device according to the first aspect or any implementation of the first aspect.

Description of the drawings

Figure 1 is a schematic block diagram of an ultrasonic fingerprint identification device according to an embodiment of the present application.

FIG. 2 is a schematic diagram of a possible specific structure of the ultrasonic fingerprint identification device shown in FIG. 1 .

FIG. 3 is a schematic diagram of another possible specific structure of the ultrasonic fingerprint identification device shown in FIG. 1 .

Figure 4 is a schematic diagram of an electronic device according to an embodiment of the present application.

Detailed ways

The technical solutions in this application will be described below with reference to the accompanying drawings.

The ultrasonic fingerprint recognition device includes an ultrasonic detection chip, a piezoelectric material layer, and an FPC connected to the ultrasonic detection chip. The ultrasonic detection chip is an Application Specific Integrated Circuit (ASIC) used for ultrasonic fingerprint recognition, such as a CMOS chip. The two surfaces of the piezoelectric material layer are respectively provided with first electrodes and second electrodes. The ultrasonic detection chip can output an excitation signal and load it to the first electrode and the second electrode. Under the action of the excitation signal, based on the piezoelectric effect, The piezoelectric material layer vibrates, thereby emitting ultrasonic signals to the finger above the display screen. The ultrasonic signals are transmitted to the surface of the finger, are emitted or scattered at the fingerprint valleys and fingerprint ridges, and return ultrasonic detection signals. The ultrasonic detection signal is transmitted to the piezoelectric material layer. Based on the inverse piezoelectric effect, a potential difference is generated between the first electrode and the second electrode, and a corresponding electrical signal is obtained. The ultrasonic detection chip processes the signal to obtain fingerprint information of the finger.

The ultrasonic fingerprint recognition device is pasted under the display screen to achieve under-screen ultrasonic fingerprint recognition. Usually, the ultrasonic fingerprint recognition device is pasted under the display screen in a front-facing manner. The ultrasonic detection chip and the flexible circuit board are pasted on the upper surface of the substrate. The ultrasonic detection chip and the flexible circuit board are interconnected so that the signal of the ultrasonic detection chip can be Output via flexible circuit board. The upper surface of the ultrasonic detection chip is a piezoelectric material layer, and the piezoelectric material layer is attached to the lower surface of the display screen. When using the front-to-side attachment method, the ultrasonic fingerprint recognition device is prone to warping after being attached to the display screen, and it is easy to show appearance marks on the display screen. Moreover, due to the complex laminate structure, it may affect the transmission of ultrasonic signals and affect ultrasonic fingerprint recognition. Device performance.

To this end, embodiments of the present application provide an ultrasonic fingerprint identification device. The ultrasonic fingerprint identification device is pasted under the display screen in a back-stick manner, which can reduce the warpage caused by the ultrasonic fingerprint identification device and the display screen being bonded, making it difficult to Appearance imprints are presented on the display screen, and the loss of ultrasonic signals is reduced through a well-designed stacked structure to improve the performance of the ultrasonic fingerprint recognition device.

FIG. 1 is a schematic block diagram of an ultrasonic fingerprint identification device 200 according to an embodiment of the present application. The display screen 100 includes a light-emitting panel and a cover plate above it. The ultrasonic fingerprint recognition device 200 can be disposed below the display screen 100 of the electronic device, for example, below a light-emitting panel of the display screen 100 such as an Active Matrix Organic Light Emitting Diode (AMOLED) panel, or Under the cover of the display screen 100, in order to realize under-screen ultrasonic fingerprint recognition. As shown in FIG. 1 , the ultrasonic fingerprint recognition device 200 includes an ultrasonic detection chip 220 and a flexible printed circuit (FPC) 230 .

Among them, the ultrasonic detection chip 220 is bonded to the display screen 100 . A piezoelectric material layer 221 and a metal wiring layer 222 are provided on the side of the ultrasonic detection chip 220 away from the display screen 100 . The piezoelectric material layer 221 is used to provide the upper surface of the display screen 100 . The finger emits an ultrasonic signal and receives an ultrasonic detection signal returned by the finger. The ultrasonic detection signal is used by the ultrasonic detection chip 220 to obtain the fingerprint information of the finger.

The FPC 230 is disposed on the side of the ultrasonic detection chip 220 away from the display screen 100, and the pads of the FPC 230 are electrically connected to the pads of the metal wiring layer 222. For example, between the pads of the FPC 230 and the pads of the metal wiring layer 222 Anisotropic Conductive Film (ACF) is pressed between them to realize the interconnection between the FPC 230 and the ultrasonic detection chip 220. Therefore, the packaging process will not generate high temperatures and affect the piezoelectric material layer 221.

In the embodiment of the present application, the ultrasonic fingerprint identification device 200 is attached to the lower surface of the display screen 100 in a back-attached manner. Contrary to the front-attached method, the ultrasonic detection chip 220 in the ultrasonic fingerprint identification device 200 is placed close to the display screen 10 and The piezoelectric material layer 221 is disposed away from the display screen 100 . The ultrasonic fingerprint identification device 200 includes an ultrasonic detection chip 220. One side of the ultrasonic detection chip 220 is directly bonded to the lower surface of the display screen 100, and the other side is a piezoelectric material layer and a metal wiring layer. Since the ultrasonic detection chip 220 and the display screen 100 are bonded together, they have a certain strength and a large bonding area. Therefore, the warpage generated after the ultrasonic fingerprint recognition device 200 and the display screen 100 are bonded is reduced, making it less likely to Appearance imprints appear on the display screen 100 . Since the ultrasonic detection signal returned by the finger passes through the piezoelectric material layer 221 and reaches the air interface, it can be fully reflected back. In addition, the encapsulated stacked structure is relatively simple, so the signal loss is reduced and the performance of the ultrasonic fingerprint identification device 200 is improved. Fingerprint recognition performance.

Hereinafter, the ultrasonic fingerprint identification device according to the embodiment of the present application will be described in detail with reference to FIGS. 2 and 3 . It should be understood that the upper part in FIGS. 2 and 3 is the lower part of the display screen 110 . The ultrasonic fingerprint recognition device 200 is disposed below the display screen 110, that is, above FIG. 2 and FIG. 3, to realize under-screen ultrasonic fingerprint recognition.

As shown in Figures 2 and 3, the ultrasonic fingerprint identification device 200 includes an ultrasonic detection chip 220 and an FPC 230. The ultrasonic detection chip 220 is pasted on the lower surface of the display screen 110 . A piezoelectric material layer 221 and a metal wiring layer 222 are provided on the side of the ultrasonic detection chip 220 away from the display screen 100 . The metal wiring layer 222 is used to electrically connect with the FPC 230 to achieve signal transmission.

The piezoelectric material layer 221 may be formed of, for example, polyvinylidene fluoride (PVDF) or polyvinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE); or, it may also be formed of lead zirconate titanate (PZT) or its relatives. Materials such as barium titanate series, lead zirconate titanate binary system are formed by adding a third ABO3 type compound to the binary system, where A represents a divalent metal ion, B represents a tetravalent metal ion or the sum of several ions is Positive price. A first electrode 2211 is provided on the surface of the piezoelectric material layer 221 close to the ultrasonic detection chip 220 , and a second electrode 2212 is provided on the surface far away from the ultrasonic detection chip 220 . The first electrode 2211 and the second electrode 2212 are electrically connected to the ultrasonic detection chip 220 . The first electrode 2211 is, for example, a planar electrode formed on the surface of the piezoelectric material layer 221 by sputtering or other methods, and the second electrode 2212 is, for example, an electrode array composed of a plurality of electrodes. The material of the first electrode 2211 may be, for example, Al, and the material of the second electrode 2212 may be, for example, Ag. The ultrasonic detection signal returned by the finger will generate an electrical signal between the first electrode 2211 and each electrode in the electrode array. The electrical signal corresponding to each electrode can be used as the pixel value of a pixel in the fingerprint pattern of the finger.

The ultrasonic detection chip 220 includes a sensor circuit module. The surface of the sensor circuit module is a piezoelectric material layer 221 and a metal wiring layer 222. The sensor circuit module is electrically connected to the first electrode 2211, the second electrode 2212 and the metal wiring layer 222. The metal wiring layer The layer 222 leads out the electrical signal generated by the ultrasonic detection chip 220 through the FPC 230.

For example, in the ultrasonic fingerprint recognition device 200 shown in Figure 2, the metal wiring layer 222 is located on the surface of the ultrasonic detection chip 220 away from the display screen 100, and the FPC 230 and the metal wiring layer 222 on the surface of the ultrasonic detection chip 220 are directly pressed together through ACF. Realize the interconnection between the ultrasonic detection chip 220 and the FPC 230.

In one implementation, the metal wiring layer 222 is a (Redistribution Layer, RDL) layer 222, and the pads of the FPC 230 and the pads of the RDL layer 222 are pressed together through ACF to realize the connection between the ultrasonic detection chip 220 and the FPC 230. interconnected. That is, new pads are formed on the surface of the ultrasonic detection chip 220 through rewiring to facilitate electrical connection between the FPC 230 and the ultrasonic detection chip 220.

By rewiring, the position, number or width of the circuit contacts (I/O pads) of the ultrasonic detection chip 220 can be changed, so that the ultrasonic detection chip 220 can be adapted to different packaging methods. In addition, by properly designing the RDL layer 222, a higher number of nodes and a thinner packaging structure can be achieved. When the pads of the FPC 230 and the pads of the RDL layer 222 are pressed together by ACF, the process operation difficulty is reduced, and the interconnection between the FPC 230 and the ultrasonic detection chip 220 is facilitated.

For example, in the ultrasonic fingerprint recognition device 200 shown in FIG. 3 , the edge of the ultrasonic detection chip 220 is provided with a step 223 that is recessed toward the display screen 100 , and the RDL layer 222 is provided within the step 223 to form an FPC for connecting to the step 223 . 230 pad. The step 225 may be formed by trenching, laser or etching, for example.

It can be seen that by setting the step 223 and using rewiring to form a pad in the step 223, the pressing surface between the pad of the FPC 230 and the pad of the RDL layer 222 is located in the step 223, reducing the FPC The height of the ultrasonic fingerprint recognition device 200 is 230, thereby reducing the overall thickness of the ultrasonic fingerprint recognition device 200 and saving the internal space of the electronic device. The depth of the step 223 may be less than or equal to 100um, for example.

In addition, since the piezoelectric material layer 221 is not resistant to high temperatures, the ACF method is used to press the pads of the FPC 230 and the pads of the RDL layer 222 to realize the interconnection between the FPC 230 and the ultrasonic detection chip 220. Compared with the SMT method, the ACF method will not generate excessive high temperatures, will not cause damage to the piezoelectric material layer 221 during the packaging process, and will not cause conflicts in manufacturing operations.

However, when the pads of the FPC 230 and the pads of the RDL layer 222 are pressed together, since the pressure head also has a certain temperature, a certain distance should be maintained between the RDL layer 222 and the piezoelectric material layer 221, that is, the step 223 The size in the direction along the surface of the display screen 100 cannot be too small.

After the pads of FPC 230 and the pads of RDL layer 222 on the surface of substrate 210 are pressed together by ACF, based on the conduction principle of ACF, the conductive particles in ACF connect the pads on the pads of RDL layer 222 and the pads of FPC 230 The pad on the screen makes the two conductive, while avoiding short circuit between two adjacent pads, thereby achieving the purpose of conduction only in the Z-axis direction perpendicular to the display screen.

The thickness of the piezoelectric material layer 221 is, for example, less than or equal to 50um; or, the piezoelectric material layer 221 is far away from the surface of the ultrasonic detection chip 220 and is closer to the display screen 100 than the FPC 230 is far away from the surface of the ultrasonic detection chip 220. As shown in Figures 2 and 3, the height of the piezoelectric material layer 221 should be less than the height of the FPC 230. While meeting the requirements for ultrasonic transmission and reception, the overall thickness of the ultrasonic fingerprint recognition device 200 is reduced, saving internal space of the electronic device.

In one implementation, as shown in FIGS. 2 and 3 , the ultrasonic detection chip 220 and the display screen 100 are bonded through an adhesive film 301 . For example, the adhesive film 301 is DAF or epoxy resin. The thickness of the adhesive film 301 is less than or equal to 50um, and/or the acoustic resistance coefficient of the adhesive film 301 is greater than or equal to 4, thereby ensuring good bonding ability without increasing the thickness of the ultrasonic fingerprint recognition device 200 and reducing signal transmission. Impact.

The adhesive film 301 should also try to match the material of the ultrasonic detection chip 220 and have good consistency and uniformity without bubbles and other impurities. This ensures the consistency of signal transmission, reduces the impact on signal transmission, and improves the fingerprint identification performance of the ultrasonic fingerprint identification device 200 .

In summary, it can be seen that the ultrasonic fingerprint identification device 200 in the embodiment of the present application is attached to the lower surface of the display screen 100 in a back-to-back manner. The ultrasonic fingerprint identification device 200 includes an ultrasonic detection chip 220, and one side of the ultrasonic detection chip 220 is directly attached to the lower surface of the display screen 100. Adhered to the lower surface of the display screen 100, the other side is a piezoelectric material layer 221 and a metal wiring layer 222. Since the ultrasonic detection chip 220 and the display screen 100 are bonded together, they have a certain strength and a large bonding area. Therefore, the warpage generated after the ultrasonic fingerprint recognition device 200 and the display screen 100 are bonded is reduced, making it less likely to Appearance imprints appear on the display screen 100 . Using the packaging solution of this application, the warpage is usually less than 30um. Since the ultrasonic detection signal returned by the finger passes through the piezoelectric material layer 221 and reaches the air interface, it can be fully reflected back. In addition, the encapsulated stacked structure is relatively simple, so the signal loss is reduced and the performance of the ultrasonic fingerprint identification device 200 is improved. Fingerprint recognition performance. At the same time, the FPC 230 and the metal wiring layer 222 of the ultrasonic detection chip 220 are pressed together through ACF to realize the interconnection between the ultrasonic detection chip 220 and the FPC 230. The packaging process will not generate high temperatures and cause damage to the piezoelectric material layer 221. Influence.

This packaging method not only reduces the complexity of the packaging structure, but also avoids the appearance marks left on the surface of the display screen 100 after the ultrasonic fingerprint recognition device 200 is attached to the display screen 100. It has less impact on the appearance of the electronic device and reduces the cost. Signal loss is eliminated, and the fingerprint recognition performance of the ultrasonic fingerprint recognition device 200 is improved.

This application also provides an electronic device 300. Please refer to FIG. 4 as well. The electronic device 300 includes a display screen 100; and the above-mentioned ultrasonic fingerprint recognition device 200. The ultrasonic detection chip 220 and the display screen 100 are bonded through the adhesive film 301, so that the ultrasonic fingerprint identification device 200 is located below the display screen 100, thereby realizing under-screen ultrasonic fingerprint identification.

As an example and not a limitation, the electronic device in the embodiment of the present application may be a portable or mobile computing device such as a terminal device, a mobile phone, a tablet computer, a notebook computer, a desktop computer, a game device, a vehicle-mounted electronic device or a wearable smart device, and Electronic databases, cars, bank automated teller machines (Automated Teller Machine, ATM) and other electronic equipment. The wearable smart devices include devices that are full-featured, large in size, and can realize complete or partial functions without relying on smartphones, such as smart watches or smart glasses, as well as devices that only focus on a certain type of application function and require integration with other devices such as smartphones. Equipment used in conjunction with it, such as various smart bracelets, smart jewelry and other equipment for physical sign monitoring.

It should be noted that, on the premise of no conflict, the various embodiments described in this application and/or the technical features in each embodiment can be combined with each other arbitrarily, and the technical solution obtained after the combination should also fall within the protection scope of this application. .

The systems, devices and methods disclosed in the embodiments of this application can be implemented in other ways. For example, some features of the method embodiments described above may be omitted or not performed. The device embodiments described above are only illustrative, and the division of units is only a logical function division. In actual implementation, there may be other divisions, and multiple units or components may be combined or integrated into another system. In addition, the coupling between units or the coupling between components may be direct coupling or indirect coupling, and the above-mentioned coupling includes electrical, mechanical or other forms of connection.

Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes and technical effects produced by the above-described devices and equipment can be referred to the corresponding processes and technical effects in the foregoing method embodiments. Herein No longer.

It should be understood that the specific examples in the embodiments of the present application are only to help those skilled in the art better understand the embodiments of the present application, but do not limit the scope of the embodiments of the present application. Those skilled in the art can use the above embodiments to Various improvements and deformations are made, and these improvements or deformations fall within the protection scope of the present application.

The above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application. should be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

An ultrasonic fingerprint identification device is characterized in that it is arranged below the display screen of an electronic device to realize under-screen ultrasonic fingerprint identification. The ultrasonic fingerprint identification device includes:

Ultrasonic detection chip, the ultrasonic detection chip is bonded to the display screen, the side of the ultrasonic detection chip away from the display screen is provided with a piezoelectric material layer and a metal wiring layer, the piezoelectric material layer is used to The finger above the display screen emits an ultrasonic signal and receives the ultrasonic detection signal returned by the finger. The ultrasonic detection signal is used by the ultrasonic detection chip to obtain the fingerprint information of the finger; and,

Flexible circuit board, the flexible circuit board is arranged on the side of the ultrasonic detection chip away from the display screen, and the pads of the flexible circuit board and the pads of the metal wiring layer are pressed by an anisotropic conductive adhesive film. combination to achieve interconnection between the ultrasonic detection chip and the flexible circuit board.
The ultrasonic fingerprint identification device according to claim 1, wherein the metal wiring layer is a rewiring layer, and the pads of the flexible circuit board and the rewiring layer are electrically conductive through the anisotropy. Film lamination.
The ultrasonic fingerprint identification device according to claim 2, characterized in that the edge of the ultrasonic detection chip is provided with a step recessed toward the display screen, and the rewiring layer is provided in the step so as to A pad for connecting the flexible circuit board is formed in the step.
The ultrasonic fingerprint identification device according to claim 3, wherein the depth of the step is less than or equal to 100um.
The ultrasonic fingerprint identification device according to any one of claims 1 to 4, characterized in that:

The thickness of the piezoelectric material layer is less than or equal to 50um; or,

The surface of the piezoelectric material layer away from the ultrasonic detection chip is closer to the display screen than the surface of the flexible circuit board away from the ultrasonic detection chip.
The ultrasonic fingerprint identification device according to any one of claims 1 to 5, characterized in that the ultrasonic detection chip and the display screen are bonded through an adhesive film, and the thickness of the adhesive film is less than or equal to 50um. , and/or the acoustic resistance coefficient of the rubber film is greater than or equal to 4.
The ultrasonic fingerprint identification device according to claim 6, wherein the adhesive film is a chip bonding film or an epoxy resin.
The ultrasonic fingerprint identification device according to any one of claims 1 to 7, characterized in that a first electrode is provided on the surface of the piezoelectric material layer close to the ultrasonic detection chip, and a first electrode is provided on the surface of the piezoelectric material layer away from the ultrasonic detection chip. A second electrode is provided on the surface. The second electrode is an electrode array composed of a plurality of electrodes. The first electrode and the second electrode are electrically connected to the ultrasonic detection chip.
The ultrasonic fingerprint identification device according to any one of claims 1 to 8, wherein the piezoelectric material layer is formed of at least one of the following materials:

Polyvinylidene fluoride, polyvinylidene fluoride-trifluoroethylene copolymer, barium titanate series, lead zirconate titanate binary system and adding a third ABO3 type compound to the binary system, where A represents Divalent metal ions, B represents tetravalent metal ions or the sum of several ions is positive tetravalent.
An electronic device, characterized by including:

display screen; and,

The ultrasonic fingerprint identification device according to any one of claims 1 to 9.