Ultrasonic fingerprint identification device and electronic device

Abstract

Embodiments of the present application provide an ultrasonic fingerprint identification device and an electronic device, which can have better performance. The ultrasonic fingerprint identification device is arranged below a display screen of the electronic device to realize under-screen ultrasonic fingerprint identification. The ultrasonic fingerprint identification device comprises: an ultrasonic fingerprint sensor chip, comprising: a silicon substrate and a piezoelectric transducer arranged on the silicon substrate, the silicon substrate comprising a circuit unit and a first anisotropic conductive adhesive (ACF) pad; a flexible circuit board comprising a second ACF pad, the second ACF pad being press-fit connected to the first ACF pad to realize electrical connection between the ultrasonic fingerprint sensor chip and the flexible circuit board; and a connecting medium layer connected between the piezoelectric transducer of the ultrasonic fingerprint sensor chip and the display screen, the connecting medium layer being used to transmit ultrasonic signals generated by the piezoelectric transducer to the display screen and transmit ultrasonic fingerprint signals to the piezoelectric transducer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fingerprint identification, and more particularly, to an ultrasonic fingerprint identification device and an electronic device. BACKGROUND

[0002] With the development of the consumer electronics industry, especially the display of mobile communication devices developing towards full screen, the demand of consumers for under-screen fingerprint identification technology is increasing. There are mainly two kinds of disclosed under-screen fingerprint identification schemes: the first is an optical scheme, and the second is an ultrasonic scheme. The performance of the optical fingerprint identification device is greatly affected by the optical transmittance of the screen. With the increase of the complexity of internal wiring of the display screen and the development of flexible screen schemes and other factors, the optical transmittance of the screen is reduced, which makes the optical fingerprint scheme unable to meet such application scenarios. The ultrasonic fingerprint identification device does not depend on the optical transmittance of the screen, and is a better alternative scheme.

[0003] In view of the good application prospect of the ultrasonic fingerprint identification device, how to improve the overall performance of the ultrasonic fingerprint identification device is an urgent technical problem to be solved. SUMMARY

[0004] Embodiments of the present application provide an ultrasonic fingerprint identification device and an electronic device, which can have better performance.

[0005] In a first aspect, an ultrasonic fingerprint identification device is provided, which is arranged below a display screen of an electronic device to realize under-screen ultrasonic fingerprint identification. The ultrasonic fingerprint identification device comprises: an ultrasonic fingerprint sensor chip, comprising: a silicon substrate and a piezoelectric transducer arranged on the silicon substrate, wherein the piezoelectric transducer comprises a piezoelectric layer, an upper electrode located above the piezoelectric layer, and a lower electrode located below the piezoelectric layer, the piezoelectric transducer is used to emit ultrasonic signals to a finger pressed on the display screen and receive ultrasonic fingerprint signals returned by the finger, the silicon substrate comprises a circuit unit and a first anisotropic conductive adhesive (ACF) pad, the circuit unit is electrically connected to the first ACF pad and is electrically connected to the upper electrode and the lower electrode to control the piezoelectric transducer to generate ultrasonic signals and detect the ultrasonic fingerprint signals for fingerprint identification; a flexible circuit board comprising a second ACF pad, the second ACF pad is press-fit connected to the first ACF pad to realize electrical connection between the ultrasonic fingerprint sensor chip and the flexible circuit board; a connection medium layer connected between the piezoelectric transducer of the ultrasonic fingerprint sensor chip and the display screen, the connection medium layer is used to transmit the ultrasonic signals generated by the piezoelectric transducer to the display screen and transmit the ultrasonic fingerprint signals to the piezoelectric transducer.

[0006] In conclusion, in the technical scheme of the embodiment of the present application, the ultrasonic fingerprint identification device including the ultrasonic fingerprint sensor chip, the flexible circuit board and the connecting medium layer is provided, wherein the ultrasonic fingerprint sensor chip and the flexible circuit board can be packaged by ACF, the reliability is high and the thickness is small, which is beneficial to improve the reliability of the ultrasonic fingerprint identification device and reduce the installation space of the ultrasonic fingerprint identification device under the display screen.

[0007] In some possible embodiments, the thickness of the silicon substrate is between 50 μm and 300 μm.

[0008] In some possible embodiments, the material of the piezoelectric layer is polyvinylidene fluoride PVDF or polyvinylidene fluoride-trifluoroethylene copolymer PVDF-TrFE, and the thickness of the piezoelectric layer is between 4 μm and 40 μm.

[0009] In some possible embodiments, the circuit unit includes a chip pad, the surface of the silicon substrate is provided with a redistribution layer RDL connected to the chip pad, and the first ACF pad is a pad provided on the RDL.

[0010] In some possible embodiments, the thickness of the RDL is between 1 μm and 10 μm.

[0011] In some possible embodiments, the circuit unit includes a chip pad, the inside of the silicon substrate is provided with a top layer of wiring connected to the chip pad, and the first ACF pad is a pad provided on the top layer of wiring.

[0012] In some possible embodiments, the surface of the chip pad is coated with a gold layer, or the surface of the chip pad is an air layer, or the surface of the chip pad is provided with an insulating layer.

[0013] In some possible embodiments, the ultrasonic fingerprint identification device includes a plurality of first ACF pads arranged side by side along one side of the silicon substrate, and the plurality of first ACF pads satisfy at least one of the following conditions: the center distance between two adjacent first ACF pads in the plurality of first ACF pads is between 50 μm and 300 μm; the length of each first ACF pad in the plurality of first ACF pads is greater than or equal to 30 μm; the width of each first ACF pad in the plurality of first ACF pads is greater than or equal to 10 μm; and the distance between each first ACF pad in the plurality of first ACF pads and the edge of the silicon substrate is greater than or equal to 10 μm.

[0014] In some possible implementation manners, the connecting medium layer comprises a medium layer, a first connecting layer and a second connecting layer, the first connecting layer is connected to the display screen and the medium layer, and the second connecting layer is connected to the medium layer and the piezoelectric transducer of the ultrasonic fingerprint sensor chip; wherein the material of the medium layer is an organic polymer material, and / or the thickness of the medium layer is between 10 μm and 200 μm.

[0015] In some possible implementation manners, the first connecting layer is provided with a first metal layer, and the second connecting layer is provided with a second metal layer; wherein the thickness of the first metal layer and / or the second metal layer is between 3 μm and 30 μm.

[0016] In some possible implementation manners, the first connecting layer is further provided with a first adhesive layer, the first adhesive layer is used for connecting the first metal layer and the display screen, wherein the absorption rate of the first adhesive layer to visible light is greater than 70%, and the thickness of the first adhesive layer is between 3 μm and 30 μm.

[0017] In some possible implementation manners, the second connecting layer is further provided with a second adhesive layer, the second adhesive layer is used for connecting the second metal layer and the piezoelectric transducer, and the thickness of the second adhesive layer is between 3 μm and 30 μm.

[0018] In some possible implementation manners, a flexible circuit board is arranged between the piezoelectric transducer and the display screen, and a flexible substrate layer in the flexible circuit board is multiplexed as the medium layer in the connecting medium layer.

[0019] In some possible implementation manners, one side of the flexible substrate layer towards the ultrasonic fingerprint sensor chip comprises a chip bonding area and an ACF compression area; the chip bonding area is provided with a first copper foil layer and a chip bonding adhesive layer, and the first copper foil layer and the chip bonding adhesive layer are multiplexed as the second connecting layer in the connecting medium layer; the ACF compression area is provided with a second copper foil layer and a second ACF pad electrically connected to the second copper foil layer.

[0020] In some possible implementation manners, one side of the second copper foil layer towards the silicon substrate is further provided with an ACF protective adhesive, the ACF protective adhesive connects the side of the second ACF pad and the side of the silicon substrate.

[0021] In some possible implementation manners, one side of the silicon substrate in the ultrasonic fingerprint sensor chip towards the flexible circuit board comprises an effective identification area, the piezoelectric transducer is arranged in the effective identification area, and the edge of the chip bonding area exceeds the edge of the effective identification area.

[0022] In some possible implementation manners, the edge of the chip bonding area exceeds the edge of the effective identification area by more than 0.05 mm.

[0023] In some possible implementations, the side of the flexible substrate layer facing the ultrasonic fingerprint sensor chip further comprises: a first transmission area for transmitting electrical signals of the flexible circuit board, the first transmission area being located on a side of the ACF compression area away from the chip bonding area, and the first transmission area being provided with a second copper foil layer and a first insulating layer covering the second copper foil layer.

[0024] In some possible implementations, the side of the flexible substrate layer facing away from the ultrasonic fingerprint sensor chip comprises: a second transmission area corresponding to the first transmission area, for transmitting electrical signals of the flexible circuit board, the second transmission area being provided with a third copper foil layer and a second insulating layer covering the third copper foil layer.

[0025] In some possible implementations, the side of the flexible substrate layer facing away from the ultrasonic fingerprint sensor chip comprises: a display screen bonding area corresponding to the chip bonding area and the ACF compression area, and the first connecting layer is arranged on the display screen bonding area.

[0026] In some possible implementations, the display screen bonding area covers the chip bonding area and the ACF compression area.

[0027] In some possible implementations, the first end of the flexible circuit board is provided with a second ACF pad, and the first end of the flexible circuit board is arranged side by side with the piezoelectric transducer on the silicon substrate; the connecting medium layer is used to provide a containing space for the first end of the flexible circuit board between the silicon substrate and the display screen.

[0028] In some possible implementations, the first end of the flexible circuit board comprises: a fourth copper foil layer and a third insulating layer, the second ACF pad is arranged on a side of the fourth copper foil layer facing the silicon substrate, and the third insulating layer is arranged on a side of the fourth copper foil layer facing away from the silicon substrate and covers the fourth copper foil layer.

[0029] In some possible implementations, the side of the fourth copper foil layer facing the silicon substrate is further provided with an ACF protective glue, and the ACF protective glue connects the side of the second ACF pad and the side of the silicon substrate.

[0030] In some possible implementations, the second end of the flexible circuit board opposite to the first end is a transmission end of the flexible circuit board, and the second end of the flexible circuit board comprises: a flexible substrate layer, a fourth copper foil layer and a third insulating layer arranged on a side of the flexible substrate layer facing the display screen, a fifth copper foil layer and a fourth insulating layer arranged on a side of the flexible substrate layer facing away from the display screen.

[0031] In some possible implementations, the side of the silicon substrate of the ultrasonic fingerprint sensor chip facing the display screen comprises: an effective identification area, the piezoelectric transducer is arranged in the effective identification area, and the edge of the connecting medium layer exceeds the edge of the effective identification area.

[0032] In some possible embodiments, the edge of the connecting medium layer is beyond the edge of the effective recognition area by more than 0.05 mm.

[0033] In some possible embodiments, the edge of at least part of the stack in the connecting medium layer is beyond the edge of the silicon substrate; the ultrasonic fingerprint recognition device further comprises a fixing adhesive, which is arranged at the edge area of at least part of the stack in the connecting medium layer, and surrounds and covers at least part of the side surface of the ultrasonic fingerprint sensor chip.

[0034] In some possible embodiments, the edge of at least part of the stack in the connecting medium layer is beyond the edge of the silicon substrate by more than 0.5 mm.

[0035] In some possible embodiments, the edge of at least the first connecting layer in the connecting medium layer is beyond the edge of the silicon substrate.

[0036] In some possible embodiments, the ultrasonic fingerprint recognition device further comprises a light shielding adhesive, which is arranged at the display screen and surrounds at least part of the stack in the connecting medium layer.

[0037] In some possible embodiments, the width of the light shielding adhesive is greater than or equal to 0.1 mm.

[0038] In some possible embodiments, at least part of the edge of the connecting medium layer is flush with at least part of the edge of the silicon substrate or is recessed by no more than 0.5 mm compared with at least part of the edge of the silicon substrate, and the ultrasonic fingerprint recognition device further comprises a fixing adhesive, which is arranged at the display screen and surrounds and covers at least part of the side surface of the connecting medium layer and the ultrasonic fingerprint sensor chip.

[0039] In some possible embodiments, the width of the fixing adhesive is greater than or equal to 0.1 mm.

[0040] In some possible embodiments, the thickness of the ultrasonic fingerprint recognition device is less than or equal to 500 μm.

[0041] In some possible embodiments, the display screen is a non-foldable screen, the lowermost layer of the non-foldable screen is a buffer layer, a buffer layer window is formed in the buffer layer, the ultrasonic fingerprint recognition device is arranged in the buffer layer window, and the connecting medium layer is attached to the substrate layer above the buffer layer in the non-foldable screen.

[0042] In some possible embodiments, the edge of the buffer layer window is beyond the edge of the connecting medium layer by more than 0.1 mm.

[0043] In some possible embodiments, the display screen is a folding screen, the lowermost layer of the folding screen is a support layer, and the ultrasonic fingerprint identification device is attached to the support layer through the connecting medium layer.

[0044] In the second aspect, an electronic device is provided, which includes a display screen and the ultrasonic fingerprint identification device of the first aspect or any one of the first aspect, wherein the display screen is configured to provide a pressing interface for a finger and receive a press of the finger; and the ultrasonic fingerprint identification device is arranged below the display screen and configured to identify a fingerprint of the finger pressed on the display screen.

[0045] In some possible embodiments, the display screen is a non-folding screen, the lowermost layer of the non-folding screen is a buffer layer, a buffer layer window is formed in the buffer layer, the ultrasonic fingerprint identification device is arranged in the buffer layer window, and the ultrasonic fingerprint identification device is attached to a substrate layer above the buffer layer in the non-folding screen.

[0046] In some possible embodiments, the display screen is a folding screen, the lowermost layer of the folding screen is a support layer, and the ultrasonic fingerprint identification device is attached to the support layer. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 FIG. 1 is a schematic structural diagram of an ultrasonic fingerprint identification device provided by an embodiment of the present application.

[0048] Figure 2 FIG. 2 is a schematic structural diagram of an ultrasonic fingerprint sensor chip provided by an embodiment of the present application.

[0049] Figure 3 FIG. 3 is another schematic structural diagram of an ultrasonic fingerprint sensor chip provided by an embodiment of the present application.

[0050] Figure 4 FIG. 4 is a schematic structural diagram of an ultrasonic fingerprint identification device provided by an embodiment of the present application. Figure 3 FIG. 5 is a schematic top view of the ultrasonic fingerprint sensor chip shown in FIG. 4.

[0051] Figure 5 FIG. 6 is another schematic structural diagram of an ultrasonic fingerprint identification device provided by an embodiment of the present application.

[0052] Figure 6 FIG. 7 is a schematic structural diagram of two connecting medium layers provided by an embodiment of the present application.

[0053] Figure 7 FIG. 8 is another schematic structural diagram of an ultrasonic fingerprint identification device provided by an embodiment of the present application.

[0054] Figure 8 FIG. 9 is a schematic structural diagram of a flexible circuit board provided by an embodiment of the present application.

[0055] Figure 9An ultrasonic fingerprint sensor chip and an ultrasonic fingerprint sensor provided by embodiments of the present application Figure 8 A schematic diagram of a connection structure of a flexible circuit board.

[0056] Figure 10 Another schematic structural diagram of an ultrasonic fingerprint identification device provided by embodiments of the present application

[0057] Figure 11 Another schematic structural diagram of an ultrasonic fingerprint identification device provided by embodiments of the present application

[0058] Figure 12 Another schematic structural diagram of an ultrasonic fingerprint identification device provided by embodiments of the present application

[0059] Figure 13 Another schematic structural diagram of an ultrasonic fingerprint identification device provided by embodiments of the present application

[0060] Figure 14 Another schematic structural diagram of an ultrasonic fingerprint identification device provided by embodiments of the present application Figure 12 Another schematic structural diagram of an ultrasonic fingerprint identification device provided by embodiments of the present application Figure 13 A schematic top view of an ultrasonic fingerprint identification device in embodiments shown in

[0061] Figure 15 Another schematic structural diagram of an ultrasonic fingerprint identification device provided by embodiments of the present application

[0062] Figure 16 Another schematic structural diagram of an ultrasonic fingerprint identification device provided by embodiments of the present application

[0063] Figure 17 Another schematic structural diagram of an ultrasonic fingerprint identification device provided by embodiments of the present application Figure 15 Another schematic structural diagram of an ultrasonic fingerprint identification device provided by embodiments of the present application Figure 16 A schematic top view of an ultrasonic fingerprint identification device in embodiments shown in

[0064] Figure 18 A schematic structural diagram of an ultrasonic fingerprint identification device under a non-foldable screen provided by embodiments of the present application

[0065] Figure 19 Another schematic structural diagram of an ultrasonic fingerprint identification device under a non-foldable screen provided by embodiments of the present application

[0066] Figure 20 A schematic structural diagram of an ultrasonic fingerprint identification device under a foldable screen provided by embodiments of the present application

[0067] Figure 21 Another schematic structural diagram of an ultrasonic fingerprint identification device under a foldable screen provided by embodiments of the present application DETAILED DESCRIPTION

[0068] The technical solutions in the embodiments of the present application will be described below with reference to the drawings.

[0069] The technical solutions of the present application can be applied to an ultrasonic fingerprint detection device. As a common application scenario, the ultrasonic fingerprint detection device provided by the embodiments of the present application can be applied to a smart phone, a tablet computer, a smart wearable device, a smart door lock or other types of electronic devices. More specifically, in the above-mentioned electronic devices, the ultrasonic fingerprint detection device can be arranged on the surface of the electronic device that interacts with the user, for example, the ultrasonic fingerprint detection device can be arranged on the front surface of the electronic device and below the display screen that interacts with the user.

[0070] Figure 1 A schematic structural diagram of an ultrasonic fingerprint recognition device 10 provided by an embodiment of the present application is shown. The ultrasonic fingerprint recognition device 10 can be arranged below the display screen 20 of an electronic device to realize under-screen ultrasonic fingerprint recognition.

[0071] As shown in Figure 1 , the ultrasonic fingerprint recognition device 10 includes an ultrasonic fingerprint sensor chip 100, a flexible printed circuit (FPC) 200 and a connecting medium layer 300.

[0072] Specifically, the ultrasonic fingerprint sensor chip 100 includes a silicon substrate 110 and a piezoelectric transducer 120 arranged on the silicon substrate, wherein the piezoelectric transducer 120 includes a piezoelectric layer 122, an upper electrode 121 above the piezoelectric layer 122 and a lower electrode 123 below the piezoelectric layer 122, the piezoelectric transducer 120 is used to emit an ultrasonic signal 22 to a finger 21 pressed on the display screen 20 and receive an ultrasonic fingerprint signal 23 returned by the finger 21. The silicon substrate 110 includes a circuit unit 111 and a first anisotropic conductive film (ACF) pad 101, the circuit unit 111 is electrically connected to the first ACF pad 101, and the circuit unit 111 is electrically connected to the upper electrode 121 and the lower electrode 123 to control the piezoelectric transducer 120 to generate the ultrasonic signal 22 and detect the ultrasonic fingerprint signal 23 for fingerprint recognition.

[0073] Optionally, in the ultrasonic fingerprint sensor chip 100, the lower surface of the silicon substrate 110 can be coated with an insulating layer, such as insulating ink, etc., to prevent external electrical devices from affecting the operation of the ultrasonic fingerprint sensor chip 100 and to ensure the fingerprint recognition performance of the ultrasonic fingerprint sensor chip 100.

[0074] The flexible circuit board 200 comprises a second ACF pad 201 which is press-bonded to the first ACF pad 101 to realize electrical connection between the ultrasonic fingerprint sensor chip 100 and the flexible circuit board 200.

[0075] The connecting medium layer 300 is connected between the piezoelectric transducer 120 of the ultrasonic fingerprint sensor chip 100 and the display screen 20, and is used to transmit the ultrasonic wave signal 22 generated by the piezoelectric transducer 120 to the display screen 20 and transmit the ultrasonic fingerprint signal 23 to the piezoelectric transducer 120.

[0076] Specifically, in the embodiment, the ultrasonic fingerprint sensor chip 100 is a special chip for ultrasonic fingerprint imaging. In the ultrasonic fingerprint sensor chip 100, the circuit unit 111 arranged on the silicon substrate 110 can be an Application Specific Integrated Circuit (ASIC) for fingerprint identification. The circuit unit 111 can excite the piezoelectric transducer 120 located above it to generate an ultrasonic wave signal 22 to the finger 21 pressed on the display screen 20. The ultrasonic wave signal 22 forms an ultrasonic fingerprint signal 23 carrying fingerprint information after being reflected by the finger 21, and the piezoelectric transducer 120 processes and converts the ultrasonic fingerprint signal 23 to obtain a fingerprint electrical signal. The circuit unit 111 can perform fingerprint imaging on the fingerprint electrical signal to perform fingerprint identification.

[0077] Specifically, the circuit unit 111 can be electrically connected to the upper electrode 121 and the lower electrode 123 of the piezoelectric transducer 120. When performing fingerprint identification, the circuit unit 111 outputs an excitation signal, for example, a sine wave or a pulse wave, to the upper electrode 121 and the lower electrode 123, and the circuit unit 111 can control the frequency and amplitude of the excitation signal. Under the action of the excitation signal, the piezoelectric layer 122 generates vibration based on the piezoelectric effect, thereby emitting an ultrasonic wave signal 22 to the finger 21. The ultrasonic fingerprint signal 23 formed after the ultrasonic wave signal 22 is reflected by the finger 21 is transmitted to the piezoelectric layer 122, and based on the inverse piezoelectric effect, a potential difference is generated between the upper electrode 121 and the lower electrode 123, thereby obtaining a corresponding fingerprint electrical signal. The circuit unit 111 acquires the fingerprint electrical signal and processes it to obtain the fingerprint pattern of the finger 21.

[0078] In an implementation manner, the upper electrode 121 is in a planar structure, and the lower electrode 123 comprises an electrode array composed of a plurality of electrodes.

[0079] For example, as shown in FIG. 2, the upper electrode 121 and the lower electrode 123 are in a planar structure, and the piezoelectric layer 122 is arranged between the upper electrode 121 and the lower electrode 123. Figure 1As shown, the upper electrode 121 covers the entire upper surface of the piezoelectric layer 122, and the lower electrode 123 is an electrode array composed of a plurality of electrodes. The ultrasonic fingerprint signal 23 returned by the finger 21 will generate an electrical signal between the upper electrode 121 and each electrode of the electrode array of the lower electrode 123, and the electrical signal corresponding to each electrode can be obtained and processed as the pixel value of a pixel in the fingerprint pattern.

[0080] The upper electrode 121 can be formed on the upper surface of the piezoelectric layer 122 by sputtering or the like, and can be a metal layer or a metal mixed coating layer; the lower electrode 123 can be formed on the lower surface of the piezoelectric layer 122 by sputtering or evaporation or the like, and the material can be aluminum or gold.

[0081] In addition, the surface of the upper electrode 121 and / or the lower electrode 123 can also be covered with a passivation layer to electrically isolate the piezoelectric transducer 120 from other medium layers other than the circuit unit 111.

[0082] Continuing to refer to Figure 1 In order to realize the electrical connection between the ultrasonic fingerprint sensor chip 100 and the external electrical device, in the embodiment of the present application, the ultrasonic fingerprint identification device 10 further comprises a flexible circuit board 200, and the ultrasonic fingerprint sensor chip 100 can be connected to the external electrical device through the flexible circuit board 200. Specifically, the flexible circuit board 200 can include a flexible copper clad laminate (FCCL). Optionally, in the flexible copper clad laminate, the copper foil layer can be provided on one side or both sides of the flexible substrate layer.

[0083] In the silicon substrate of the ultrasonic fingerprint sensor chip 100, in addition to the circuit unit 111, a first ACF pad 101 is also provided. Corresponding to the first ACF pad 101, a second ACF pad 101 is provided in the flexible circuit board 200, and the first ACF pad 101 and the second ACF pad 201 can be pressed together through an ACF adhesive layer to realize a more stable and reliable electrical connection.

[0084] In some embodiments, the number of first ACF pads 101 in the ultrasonic fingerprint sensor chip 100 can be multiple, and correspondingly, the number of second ACF pads 201 in the flexible circuit board 200 can also be multiple. Through the mutual connection between the plurality of first ACF pads 101 and the plurality of second ACF pads 201, the mutual transmission of various signals between the ultrasonic fingerprint sensor chip 100 and the flexible circuit board 200 can be realized.

[0085] Optionally, the first ACF pad 101 and the second ACF pad 201 can be referred to as "gold fingers" in some implementations, i.e., the surfaces of the first ACF pad 101 and the second ACF pad 201 are coated with a gold layer or a nickel-gold layer to meet the requirements of the ACF pressing process and connection reliability.

[0086] By the technical solution of this embodiment, the ultrasonic fingerprint sensor chip 100 and the flexible circuit board 200 can be connected to each other through the ACF pads. The ACF process can be implemented using the ultrasonic fingerprint sensor chip 100 as a support without an additional support. The ultrasonic fingerprint recognition device 10 formed by connecting the ultrasonic fingerprint sensor chip 100 and the flexible circuit board 200 through the ACF process can have a smaller thickness, facilitating the installation of the ultrasonic fingerprint recognition device 10 under the display screen 20 and saving the installation space of the ultrasonic fingerprint recognition device 10 under the display screen 20.

[0087] Continuing to refer to Figure 1 , in order to realize the installation of the ultrasonic fingerprint recognition device 10 under the display screen 20, the present application embodiment further includes a connection medium layer 300 connected between the piezoelectric transducer 120 of the ultrasonic fingerprint sensor chip 100 and the display screen 20, thereby providing a transmission medium for the ultrasonic wave signal 22 generated by the piezoelectric transducer 120 and the ultrasonic fingerprint signal 23 returned via the user's finger 21.

[0088] By the technical solution of this embodiment, the connection medium layer 300 not only can be used to realize the installation of the ultrasonic fingerprint sensor chip 100 and the circuit board 200 under the display screen 20, but also can provide a transmission medium for the ultrasonic wave signal 22 and the ultrasonic fingerprint signal 23, thereby guaranteeing the fingerprint recognition performance of the ultrasonic fingerprint recognition device 10.

[0089] In summary, in the technical solution of the present application embodiment, an ultrasonic fingerprint recognition device 10 including an ultrasonic fingerprint sensor chip 100, a flexible circuit board 200, and a connection medium layer 300 is provided. The ultrasonic fingerprint sensor chip 100 and the flexible circuit board 200 can be implemented by ACF packaging, which has high reliability and a small thickness, thereby being beneficial to improve the reliability of the ultrasonic fingerprint recognition device 10 and reduce the installation space of the ultrasonic fingerprint recognition device 10 under the display screen 20. Further, the ultrasonic fingerprint sensor chip 100 is directly connected and installed to the display screen 20 through the connection medium layer 300, and the connection medium layer 300 can provide a transmission medium for the ultrasonic wave signal 22 and the ultrasonic fingerprint signal 23 used for fingerprint recognition, thereby comprehensively guaranteeing the fingerprint recognition performance of the ultrasonic fingerprint recognition device 10.

[0090] Optionally, in some embodiments, the thickness of the silicon substrate 110 in the ultrasonic fingerprint sensor chip 100 described above can be between 50 μm and 300 μm, for example, specifically between 50 μm and 160 μm, i.e. greater than or equal to 50 μm and less than or equal to 160 μm. When silicon is used as the material of the substrate, the thickness of the silicon substrate 110 has an impact on the resonance frequency of the piezoelectric layer 122 in the piezoelectric transducer 120. Therefore, by setting the thickness of the silicon substrate 110 between 50 μm and 300 μm, the impact of the silicon substrate 110 on the resonance frequency of the piezoelectric layer 122 can be minimized, thereby improving the performance of fingerprint identification.

[0091] It should be understood that the resonance frequency of the piezoelectric layer 122 is the operating frequency of the ultrasonic fingerprint identification device 10 in the embodiments of the present application, and the resonance frequency is also the frequency of the ultrasonic signal generated by the piezoelectric layer 122.

[0092] Optionally, in some embodiments, the material of the piezoelectric layer 122 can be polyvinylidene difluoride (PVDF) or polyvinylidene difluoride-trifluoroethylene (PVDF-TrFE), for example.

[0093] The thickness of the piezoelectric layer 122 also has an impact on its resonance frequency. Therefore, in one implementation, the thickness of the piezoelectric layer 122 is between 4 μm and 40 μm, i.e. greater than or equal to 4 μm and less than or equal to 40 μm, so that the resonance frequency of the piezoelectric layer 122 is within the frequency range suitable for fingerprint identification, thereby further improving the performance of fingerprint identification.

[0094] When the thickness of the silicon substrate 110 is between 50 μm and 300 μm, and the thickness of the piezoelectric layer 122 is between 4 μm and 40 μm, the resonance frequency of the piezoelectric layer 122 can meet the requirements of fingerprint identification.

[0095] To illustrate the arrangement of the first ACF pad 101 of the ultrasonic fingerprint sensor chip 100 in the embodiments of the present application in the chip 100, Figure 2 and Figure 3 Several schematic structural diagrams of the ultrasonic fingerprint sensor chip 100 provided by the embodiments of the present application are shown.

[0096] As Figure 2As shown, in the silicon substrate 110 of the ultrasonic fingerprint sensor chip 100, the circuit unit 111 may include a chip pad 112. A redistribution layer (RDL) 113 connected to the chip pad 112 is provided on the surface of the silicon substrate 110. The first ACF pad 101 is a pad provided on the RDL 113.

[0097] Specifically, multiple layers of metal traces can be disposed inside the silicon substrate 110 to connect multiple devices inside the silicon substrate 110 to form a circuit unit 111. The top layer of these multilayer metal traces is covered with an insulating layer to protect the metal traces inside the silicon substrate 110; the insulating layer on the surface of the top layer trace is the surface material layer of the silicon substrate 110. Optionally, the insulating layer on the surface of the top layer trace can have windows to expose a portion of the top layer trace, forming a chip pad 112.

[0098] To facilitate the execution of the ACF process on the ultrasonic fingerprint sensor chip 100, in this embodiment, a first ACF pad 101 can be formed through RDL 113. Specifically, one end of RDL 113 is connected to the chip pad 112, and the other end of RDL 113 is located on the surface of the silicon substrate 110. The first ACF pad 101 can be formed on RDL 113.

[0099] In some examples, the material of the RDL 113 can be gold, and one end of the RDL 113 located on the surface of the silicon substrate 110 can be directly used as the first ACF pad 101.

[0100] In other examples, the material of the RDL 113 can be other conductive metal materials, in which case a gold layer can be coated on one end of the RDL 113 located on the surface of the silicon substrate 110 to form the first ACF pad 101.

[0101] Optionally, in order to ensure the reliability of the ACF process and the reliability of the electrical connection between the flexible circuit board 200 and the ultrasonic fingerprint sensor chip 100, the thickness of RDL 113 can be between 1μm and 10μm.

[0102] like Figure 3 As shown, in the silicon substrate 110 of the ultrasonic fingerprint sensor chip 100, the circuit unit 111 may also include a chip pad 112. The silicon substrate 110 is provided with a top layer trace 114 connected to the chip pad 112. The first ACF pad 101 is a pad provided on the top layer trace 114.

[0103] Specifically, the relevant scheme for the chip pad 112 in this embodiment can be found above. Figure 2According to the relevant description, the chip pad 112 can be a pad formed on the top layer trace 114, or in other words, a local area in the top layer trace 114 can be used as the chip pad 112.

[0104] Since the silicon substrate 110 has a top layer trace 114 inside, the first ACF pad 101 can also be directly formed using the top layer trace 114. Specifically, the insulating layer on the surface of the top layer trace 114 can be opened to expose a portion of the top layer trace 114, and a gold layer can be coated on this portion to form the first ACF pad 101 disposed on the top layer trace 114.

[0105] Specifically, in this embodiment, since the top layer trace 114 of the silicon substrate 110 is generally made of aluminum, the conductivity of which cannot meet the requirements of the ACF process, gold plating is required on the surface of the top layer trace 114 to form the first ACF pad 101 that meets the requirements of the ACF process, thereby ensuring the reliability of the connection between the flexible circuit board 200 and the ultrasonic fingerprint sensor chip 100.

[0106] Alternatively, in some implementations, such as Figure 3 As shown in Figure (a), the surface of chip pad 112 can be an air layer, or, as... Figure 3 As shown in Figure (b), the surface of the chip pad 112 is provided with an insulating layer 103, or, as... Figure 3 As shown in Figure (c), the surface of chip pad 112 is coated with a gold layer 104.

[0107] exist Figure 3 In the embodiments shown in Figures (a) and (c), the electrical signal of the chip pad 112 can be detected by the user. Since the chip pad 112 is connected to and close to the first ACF pad 101, the electrical signal of the chip pad 112 can be approximately understood as being the same as the electrical signal of the first ACF pad 101. Because the first ACF pad 101 is coated with a gold layer, and this gold layer structure is relatively fragile and not easily detected directly, the electrical signal of the first ACF pad 101 can be detected by detecting the electrical signal of the chip pad 112, thus facilitating the location and analysis of faults in the ultrasonic fingerprint sensor chip 100.

[0108] exist Figure 3 In the embodiment shown in Figure (b), an insulating layer 103 is provided on the surface of the chip pad 112. The insulating layer 103 can prevent the first ACF pad 101 from short-circuiting with the chip pad 112 during the process of pressing the first ACF pad 101 onto the flexible circuit board 200 with ACF adhesive, thereby improving the manufacturing yield of the ultrasonic fingerprint recognition device 10.

[0109] Figure 4 It shows Figure 3 A schematic top view of the ultrasonic fingerprint sensor chip 100 shown in Figure (c).

[0110] like Figure 4 As shown, in this embodiment, the ultrasonic fingerprint recognition device 10 includes a plurality of first ACF pads 101 arranged side by side along one side of a silicon substrate 110. The plurality of first ACF pads 101 satisfy at least one of the following conditions: the center distance between two adjacent first ACF pads 101 is between 50 μm and 300 μm; the length of each first ACF pad 101 is greater than or equal to 30 μm; the width of each first ACF pad 101 is greater than or equal to 10 μm; and the distance between the edge of each first ACF pad 101 and the edge of the silicon substrate 110 is greater than or equal to 10 μm.

[0111] Specifically, in this embodiment, the size of the plurality of first ACF pads 101 can be designed to be relatively large, thereby ensuring the reliability of the ACF process and ensuring the connection reliability between the flexible circuit board 200 and the ultrasonic fingerprint sensor chip 100. In addition, the center distance between two adjacent first ACF pads 101 is between 50μm and 300μm, which can reduce the risk of short circuits between adjacent pads.

[0112] Figure 5 Another schematic structural diagram of the ultrasonic fingerprint recognition device 10 provided in this application embodiment is shown.

[0113] like Figure 5 As shown in this embodiment, the connecting dielectric layer 300 may include a first connecting layer 310, a dielectric layer 330, and a second connecting layer 320. The first connecting layer 310 is connected to the display screen 20 and the dielectric layer 330, and the second connecting layer 320 is connected to the dielectric layer 330 and the piezoelectric transducer 120. The dielectric layer 330 is made of an organic polymer material, and / or its thickness is between 10 μm and 200 μm.

[0114] Specifically, to ensure the transmission of ultrasonic waves between the piezoelectric transducer 120 and the display screen 20 and reduce transmission loss, a dielectric layer 330 can be provided in the connecting dielectric layer 300. This dielectric layer 330 can be a dielectric layer matched to both the display screen 20 and the piezoelectric transducer 120. For example, to ensure optimal signal transmission performance when passing through the dielectric layer 330, the acoustic impedance of the stacked layers adjacent to the dielectric layer 330 can be considered. If the acoustic impedances of the adjacent stacked layers on both sides of the dielectric layer 330 are Z1 and Z2 respectively, when the acoustic impedance of the dielectric layer 330... The medium layer 330 and its adjacent layers can achieve optimal acoustic impedance matching. The acoustic impedance Z is an important indicator for evaluating the signal transmission in the medium layer 330, Z = pc, p is the material density of the medium layer 330, and c is the transmission speed of the ultrasonic wave, i.e., the acoustic velocity. For solid materials, the acoustic velocity c is related to the mechanical parameters thereof and satisfies where Y is the Young's modulus, and v is the Poisson's ratio.

[0115] As an example, in order to match the layers in the display screen 20, the material of the medium layer 330 can be an organic polymer material, such as polyethylene terephthalate (PET), polyimide (PI), thermoplastic polyurethane (TPU), and the like. Alternatively, in some alternative embodiments, the material of the medium layer 330 can also be an inorganic material, such as carbon fiber and glass, and the like.

[0116] Meanwhile, the transmission rate of the ultrasonic wave is also related to the material thickness. For example, it can be known through experiments that when the thickness d of the medium layer 330 and the wavelength λ of the ultrasonic wave satisfy d = (2n + 1) * (λ / 4), the signal attenuation is large; and when d = λ / 2, the influence on the signal transmission is small. Therefore, in some embodiments, the thickness of the medium layer 330 can be between 10 μm and 200 μm, for example, 50 μm.

[0117] In addition, through the setting of the thickness of the medium layer 330, not only is the transmission of the ultrasonic wave by the medium layer 330 facilitated, but also a certain gap can be provided below the display screen 20 to accommodate the flexible circuit board 200 connected to the ultrasonic fingerprint sensor chip 100.

[0118] Further, in order to realize the connection of the medium layer 330 to the display screen 20 and the piezoelectric transducer 120, the connecting medium layer 300 further includes a first connecting layer 310 and a second connecting layer 320. The first connecting layer 310 and the second connecting layer 320 can have a glue layer to facilitate the connection of the medium layer 330 between the piezoelectric transducer 120 and the display screen 20.

[0119] Optionally, in some embodiments, as shown in FIG. 4, the connecting medium layer 300 can further include a third connecting layer 330. The third connecting layer 330 can be arranged between the first connecting layer 310 and the second connecting layer 320, and can be connected to the first connecting layer 310 and the second connecting layer 320. Figure 5As shown, in addition to the upper electrode 121, the piezoelectric layer 122 and the lower electrode 123, the piezoelectric transducer 120 can further include a protective layer 124 covering the upper surface of the upper electrode 121. The protective layer 124 can be used to protect the upper electrode 121 from oxidation and other problems, and also to protect the piezoelectric layer 122 to ensure its piezoelectric performance. By providing the protective layer 124, the piezoelectric layer 122 and the upper electrode 121 can be prevented from permeating and failing under high temperature and high humidity conditions, thereby improving the safety and reliability of the ultrasonic fingerprint identification device 10.

[0120] Based on the piezoelectric transducer 120 including the protective layer 124, the connecting medium layer 300 can be used to connect the protective layer 124 and the display screen 20. Specifically, the second connecting layer 320 in the connecting medium layer 300 is connected to the protective layer 124 and the display screen 20.

[0121] Figure 6 The schematic structural diagrams of two connecting medium layers 300 provided by the embodiments of the present application are shown.

[0122] As shown in (a) and (b) of FIG. 1, Figure 6 The first metal layer 311 can be provided in the first connecting layer 310, and the second metal layer 321 can be provided in the second connecting layer 320. The thickness of the first metal layer 311 is between 3 μm and 30 μm, and / or the thickness of the second metal layer 321 is between 3 μm and 30 μm.

[0123] By way of example but not limitation, the materials of the first metal layer 311 and the second metal layer 321 can be copper, in other words, the first metal layer 311 and the second metal layer 321 can be copper foil layers.

[0124] By the technical solution of the embodiment, the two metal layers in the first connecting layer 310 and the second connecting layer 320 can be matched with the acoustic impedance of the display screen 20 and the piezoelectric transducer 120, and the two metal layers can produce ultrasonic wave coherent superposition, so as to further improve the transmission performance of the first connecting layer 310 and the second connecting layer 320 to the ultrasonic wave, thereby improving the fingerprint identification performance of the ultrasonic fingerprint identification device 10.

[0125] Based on the above-mentioned embodiments, as shown in Figure 6As shown in FIG. 1(a) and FIG. 1(b), the first connection layer 310 can further include a first adhesive layer 312 for connecting the display screen 20 and the first metal layer 311. As an example but not limitation, the first adhesive layer 312 can be a double-sided adhesive tape, such as a pressure sensitive adhesive (PSA) or the like.

[0126] Optionally, the first adhesive layer 312 can be a low-transmittance (e.g., black) adhesive layer. The first adhesive layer 312 has an absorption rate of visible light greater than 70%, for example, the first adhesive layer 312 has an absorption rate of visible light between 70% and 90%. Specifically, the first adhesive layer 312 is an adhesive layer of the first connection layer 310 facing the display screen 20. By setting the first adhesive layer 312 as a low-transmittance (e.g., black) adhesive layer, the appearance problem caused by the ultrasonic fingerprint identification device 10 being arranged under the display screen 20 can be reduced or avoided.

[0127] Optionally, the thickness of the first adhesive layer 312 is between 3 μm and 30 μm. By setting the thickness of the first adhesive layer 312, the first adhesive layer 312 can have good and reliable adhesion, and the installation reliability of the ultrasonic fingerprint identification device 10 under the display screen 20 can be improved.

[0128] Similarly, as shown in FIG. 1(a) and FIG. 1(b), the second connection layer 320 can further include a second adhesive layer 322 for connecting the piezoelectric transducer 120 and the second metal layer 321. The second adhesive layer 322 can also be a double-sided adhesive tape, for example but not limitation, the second adhesive layer 322 can also be a PSA adhesive layer. Figure 6

[0129] Optionally, in the second connection layer 320, the thickness of the second adhesive layer 322 can be between 3 μm and 30 μm. Specifically, the second adhesive layer 322 is an adhesive layer facing the ultrasonic fingerprint sensor chip 100, and is used to connect the piezoelectric transducer 120 in the ultrasonic fingerprint sensor chip 100. During the manufacturing process of the ultrasonic fingerprint sensor chip 100, due to process problems, the ultrasonic fingerprint sensor chip 100 can be warped, affecting the overall performance of the ultrasonic fingerprint identification device 10 and the thickness space required. Therefore, in this embodiment, by setting the thickness of the second adhesive layer 322, the warping of the ultrasonic fingerprint sensor chip 100 can be better absorbed under the adhesion of the second adhesive layer 322, the overall performance of the ultrasonic fingerprint identification device 10 can be improved, and the thickness space required by the ultrasonic fingerprint identification device 10 under the display screen 20 can be reduced.

[0130] ​In the above embodiments, the connection of the first metal layer 311 to the display screen 20 and the connection of the second metal layer 321 to the piezoelectric transducer 120 are achieved by disposing the first adhesive layer 312 and the second adhesive layer 322 in the first connecting layer 310 and the second connecting layer 320, respectively. Optionally, in some embodiments, as shown in (b) of FIG. 13, a third adhesive layer 313 can be further disposed in the first connecting layer 310, and a fourth adhesive layer 323 can be further disposed in the second connecting layer 320, respectively. The third adhesive layer 313 is configured to connect the first metal layer 311 to the dielectric layer 330, and the fourth adhesive layer 323 is configured to connect the second metal layer 321 to the dielectric layer 330. Figure 6

[0131] In this case, the first connecting layer 310 and the second connecting layer 320 are both three-layer structures, and the middle layer of the three-layer structure is a metal layer (i.e., the first metal layer 311 and the second metal layer 321 described above). The upper and lower surfaces of the metal layer are coated with adhesive layers, so as to facilitate the connection between the metal layer and other layers.

[0132] Similarly to the thickness range of the first adhesive layer 312 and the second adhesive layer 322, the thickness of the third adhesive layer 313 and / or the fourth adhesive layer 323 can also be between 3 μm and 30 μm, so as to ensure the adhesion of the third adhesive layer 313 and / or the fourth adhesive layer 323. In some possible embodiments, in order to reduce the thickness of the first connecting layer 310 and the second connecting layer 320, and thus reduce the space of the ultrasonic fingerprint identification device 10 under the display screen 20, the thickness of the third adhesive layer 313 and / or the fourth adhesive layer 323 can be appropriately reduced. That is, the thickness of the third adhesive layer 313 can be less than the thickness of the first adhesive layer 312, and / or the thickness of the fourth adhesive layer 323 can be less than the thickness of the second adhesive layer 322.

[0133] Alternatively, in other embodiments, as shown in FIG. 14, the first connecting layer 310 and the second connecting layer 320 can be two-layer structures, and the metal layer (i.e., the first metal layer 311 and the second metal layer 321 described above) is directly connected to the dielectric layer 330. Figure 6 ​As shown in (a) of FIG. 10, the first connecting layer 310 and the second connecting layer 320 can also not be provided with the third adhesive layer 313 and / or the fourth adhesive layer 323, i.e., the first metal layer 311 can be directly fixedly connected to the medium layer 330, and / or the second metal layer 321 can be directly fixedly connected to the medium layer 330. No adhesive layer is provided between the first metal layer 311 and the second metal layer 321 and the medium layer 330, and stable connection between the first metal layer 311 and the second metal layer 321 and the medium layer 330 can be achieved through various processes. For example, the upper and lower surfaces of the medium layer 330 are heated and laminated together with the first metal layer 311 and the second metal layer 321 for pressure heating, so that the first metal layer 311 and the second metal layer 321 are stably connected to the medium layer 330; for another example, the first metal layer 311 and the second metal layer 321 are prepared on the upper and lower surfaces of the medium layer 330 through sputtering, evaporation or other process methods, so that the first metal layer 311 and the second metal layer 321 are stably connected to the medium layer 330.

[0134] Figure 7 Another schematic structural diagram of the ultrasonic fingerprint identification device 10 provided by the embodiment of the present application is shown.

[0135] As shown in Figure 7 In the embodiment of the present application, the flexible circuit board 200 is arranged between the piezoelectric transducer 120 and the display screen 20, and at least part of the laminated layers in the flexible circuit board 200 can be reused as the connecting medium layer 300.

[0136] Specifically, the flexible circuit board 200 can be arranged above the ultrasonic fingerprint sensor chip 100, and the piezoelectric transducer 120 of the ultrasonic fingerprint sensor chip 100 and the display screen 20 can be connected by using the flexible circuit board 200. While the display screen 20 and the ultrasonic fingerprint sensor chip 100 are connected by using the flexible circuit board 200, the side of the flexible circuit board 200 facing the ultrasonic fingerprint sensor chip 100 is provided with a second ACF pad 201, the second ACF pad 201 is arranged opposite to the first ACF pad 101 arranged on the upper surface of the silicon substrate 110, and the first ACF pad 101 and the second ACF pad 201 are press-bonded and connected to each other through an ACF adhesive layer 202.

[0137] By the technical solutions of the embodiments of the present application, while the flexible circuit board 200 is used to electrically connect the ultrasonic fingerprint sensor chip 100 to transmit the signals of the ultrasonic fingerprint sensor chip 100, the flexible circuit board 200 can also be reused as the connection medium layer 300 connecting the ultrasonic fingerprint sensor chip 100 and the display screen 20, so as to match and improve the transmission of ultrasonic waves between the ultrasonic fingerprint sensor chip 100 and the display screen 20. The technical solutions of the embodiments can guarantee the fingerprint recognition performance of the ultrasonic fingerprint recognition device 10, and also simplify the overall structure of the ultrasonic fingerprint recognition device 10, facilitating the manufacturing and installation of the ultrasonic fingerprint recognition device 10.

[0138] Specifically, in some embodiments, the flexible substrate layer in the flexible circuit board 200 can be reused as the medium layer 330 in the connection medium layer 300, and the metal layer in the flexible circuit board 200 can be reused as the first metal layer 311 and / or the second metal layer 321 in the connection medium layer 300.

[0139] It can be understood that the flexible circuit board 200 can be prepared by stacking a metal material layer on one side or both sides of the flexible substrate layer. The flexible substrate layer in the flexible circuit board 200 is generally an organic polymer material, such as PET, PI, etc., and the metal layer in the flexible circuit board 200 can be a copper foil layer covering the surface of the flexible substrate layer. Therefore, the flexible substrate layer in the flexible circuit board 200 can be reused as the medium layer 330 in the above-mentioned connection medium layer 300, and the metal layer can also be reused as the first metal layer 311 and / or the second metal layer 321 in the above-mentioned connection medium layer 300.

[0140] By the technical solutions of the embodiments, the flexible circuit board 200 does not need to be modified and processed too much, and can be directly applied to the ultrasonic fingerprint recognition device 10, so as to further improve the manufacturing efficiency of the ultrasonic fingerprint recognition device 10 and reduce the processing cost.

[0141] In order to facilitate the description of the related structure of the flexible circuit board 200 provided by the embodiments of the present application, Figure 8 A schematic structural diagram of a flexible circuit board 200 is separately shown.

[0142] In the flexible circuit board 200, the side of the flexible substrate layer 210 (the lower surface of the flexible substrate layer 210 shown in the figure) facing the ultrasonic fingerprint sensor chip 100 comprises a chip bonding area 231 and an ACF compression area 232. The chip bonding area 231 is provided with a first copper foil layer 221 and a chip bonding adhesive layer 261, and the whole of the first copper foil layer 221 and the chip bonding adhesive layer 261 can be reused as the second connection layer 320 in the connection medium layer 300 described above. The ACF compression area 232 is provided with a second copper foil layer 222 and a second ACF pad 201 electrically connected to the second copper foil layer 222.

[0143] Specifically, in this embodiment, the flexible substrate layer 210 can completely cover the ultrasonic fingerprint sensor chip 100. On the side of the flexible substrate layer 210 facing the ultrasonic fingerprint sensor chip 100, the chip bonding area 231 is arranged corresponding to the piezoelectric transducer 120 of the ultrasonic fingerprint sensor chip 100, and the ACF compression area 232 is arranged corresponding to the first ACF pad 101 of the ultrasonic fingerprint sensor chip 100. The chip bonding area 231 and the ACF compression area 232 are two independent areas and do not overlap each other.

[0144] The part of the flexible substrate layer 210 corresponding to the chip bonding area 231 can be reused as the medium layer 330 in the connection medium layer 300 in the application embodiment described above, the first copper foil layer 221 arranged in the chip bonding area 231 can be reused as the second metal layer 321 in the second connection layer 320 in the connection medium layer 300, and the chip bonding adhesive layer 261 can be reused as the second adhesive layer 322 in the second connection layer 320.

[0145] Optionally, in this embodiment, the flexible substrate layer 210 is provided with a first adhesive layer 241 between the first copper foil layer 221 and the second copper foil layer 222. Figure 8 In the embodiment shown, no adhesive layer is arranged between the flexible substrate layer 210 and the first copper foil layer 221, or an adhesive layer can also be arranged between the flexible substrate layer 210 and the first copper foil layer 221, which can be reused as the fourth adhesive layer 323 in the second connection layer 320.

[0146] In addition to the first copper foil layer 221 described above, the side of the flexible substrate layer 210 facing the ultrasonic fingerprint sensor chip 100 is also provided with a second copper foil layer 222, which is located in the ACF compression area 232, and the ACF compression area 232 is also provided with a second ACF pad 201 electrically connected to the second copper foil layer 222.

[0147] Specifically, the second copper foil layer 222 can be disconnected from the first copper foil layer 221, i.e., the first copper foil layer 221 is not connected to the second copper foil layer 222, to prevent the relevant electrical signals in the second copper foil layer 222 from being transmitted to the first copper foil layer 221 to interfere with the transmission of ultrasonic waves. The first copper foil layer 221 only serves as a medium layer for transmitting ultrasonic waves and does not serve as an electrical signal transmission layer, thereby ensuring the transmission quality of ultrasonic waves and further ensuring the fingerprint recognition performance of the ultrasonic fingerprint recognition apparatus 10.

[0148] Optionally, in the embodiment shown in FIG. 6, the second copper foil layer 222 can be connected to the first ACF pad 310 to form a circuit trace layer in the flexible circuit board 300. Figure 8 In the embodiment shown in FIG. 6, a first copper deposition layer 351 is further formed between the second copper foil layer 222 and the second ACF pad 201. The first copper deposition layer 351 can be connected to the second copper foil layer 222 to form a circuit trace layer in the flexible circuit board 300. The second ACF pad 201 can be connected to the second copper foil layer 222 through the first copper deposition layer 351, thereby forming an input / output interface for electrical signals in the flexible circuit board 300.

[0149] Through the technical solutions of the embodiments of the present application, in the flexible circuit board 200, the side of the flexible substrate layer 210 facing the ultrasonic fingerprint sensor chip 100 includes two mutually independent chip bonding areas 231 and ACF compression areas 232. The chip bonding areas 231 are used to dispose the first copper foil layer 221 and are connected to the piezoelectric transducer 120 of the ultrasonic fingerprint sensor chip 100 through the first copper foil layer 221, thereby providing a good transmission medium for ultrasonic waves of the piezoelectric transducer 120. The ACF compression areas 232 are used to dispose the second copper foil layer 222 and the second ACF pad 201 and are connected to the first ACF pad 101 of the ultrasonic fingerprint sensor chip 100 through the second ACF pad 201, thereby providing effective electrical signal transmission for the ultrasonic fingerprint sensor chip 100. Through the technical solutions, the overall performance of the ultrasonic fingerprint sensor chip 100 and the ultrasonic fingerprint recognition apparatus 10 in which the ultrasonic fingerprint sensor chip 100 is located can be comprehensively ensured.

[0150] Optionally, in the embodiment shown in FIG. 6, the upper surface of the flexible substrate layer 210 can not be provided with a copper foil layer to facilitate the attachment of the flexible circuit board 300 to the display screen 20. When it is necessary to attach the flexible circuit board 300 to the display screen 20, a connection layer can be disposed on the upper surface of the flexible substrate layer 210 to connect the flexible circuit board 300 and the display screen 20. The structure of the connection layer can be the same as that of the first connection layer 310 in the above embodiment. Figure 8

[0151] ​Alternatively, in some other embodiments, the upper surface of the flexible substrate layer 210 can also be provided with a copper foil layer, which can reuse the first metal layer 311 in the above-mentioned connecting medium layer 300. When the flexible circuit board 200 needs to be attached to the display screen 20, an adhesive layer can be provided on the surface of the copper foil layer, so as to connect the flexible circuit board 200 and the display screen 20. The adhesive layer can have the same structure as the first adhesive layer 312 in the above-mentioned embodiments.

[0152] Figure 9 It is shown that the present application provides an ultrasonic fingerprint sensor chip 100 and a flexible circuit board 200 connected to the ultrasonic fingerprint sensor chip 100. Figure 8 The connection structure of the flexible circuit board 200 is shown in the schematic diagram.

[0153] As shown in the above-mentioned embodiments, the side of the silicon substrate 110 of the ultrasonic fingerprint sensor chip 100 facing the flexible circuit board 200 (the upper surface of the silicon substrate 110 shown in the figure) includes an effective identification area 115, and the piezoelectric transducer 120 is arranged in the effective identification area 115, and the edge of the chip bonding area 231 exceeds the edge of the effective identification area 115. Figure 9 Specifically, in the ultrasonic fingerprint sensor chip 100, the silicon substrate 110 can be provided with pixel circuits connected to the lower electrode 123 in the piezoelectric transducer 120. Specifically, the lower electrode 123 is a lower electrode array formed by a plurality of electrodes, and the silicon substrate 110 is formed with a pixel circuit array, and each circuit in the pixel circuit array is connected to one electrode in the lower electrode array. The area where the pixel circuit array is located can be referred to as the effective identification area 115 in the present application. The circuit unit 111 in the above-mentioned embodiments can include the pixel circuit array in the present application and other auxiliary circuits, and the area where the auxiliary circuits are located can be referred to as the non-effective identification area.

[0154] It can be understood that the piezoelectric transducer 120 needs to be arranged in the effective identification area 115, so that the lower electrode 123 in the piezoelectric transducer 120 is connected to the pixel circuit in the effective identification area 115. The area of the piezoelectric layer 122 and the upper electrode 121 in the piezoelectric transducer 120 can be slightly larger than or equal to the area of the effective identification area 115, that is, the piezoelectric layer 122 and the upper electrode 121 can be covered above the effective identification area 115.

[0155]

[0156] ​If the chip bonding area 231 of the flexible circuit board 200 and the effective recognition area 115 of the ultrasonic fingerprint sensor chip 100 are designed to be the same size, when the piezoelectric transducer 120 arranged in the effective recognition area 115 is bonded to the chip bonding area 231 of the flexible circuit board 200, due to the influence of mounting process and manufacturing process, etc., the flexible circuit board 200 may not be able to completely cover the effective recognition area 115, thereby affecting the transmission of the ultrasonic signal of the ultrasonic fingerprint sensor chip 100 by the flexible circuit board 200.

[0157] Therefore, in the embodiment of the present application, the edge of the chip bonding area 231 of the flexible circuit board 200 needs to exceed the edge of the effective recognition area 115 of the ultrasonic fingerprint sensor chip 100, which can reduce the influence of process fluctuation on the connection performance between the flexible circuit board 200 and the ultrasonic fingerprint sensor chip 100, and guarantee the transmission of the ultrasonic signal of the ultrasonic fingerprint sensor chip 100 by the flexible circuit board 200.

[0158] As an example, as shown in Figure 9 The distance between the edge of the chip bonding area 231 and the edge of the effective recognition area 115 is shown as D, and D≥0.05mm. In other words, the edge of the chip bonding area 231 can exceed the edge of the effective recognition area 115 by 0.05mm or more.

[0159] Further, in order to more effectively guarantee the transmission of the ultrasonic signal by the flexible circuit board 200, the edge of the chip bonding area 231 can exceed the edge of the piezoelectric transducer 120, for example, the edge of the chip bonding area 231 can exceed the edge of the piezoelectric transducer 120 by 0.05mm or more.

[0160] Continuing to refer to Figure 9 In the embodiment of the present application, the side of the second copper foil layer 222 of the flexible circuit board 200 facing the silicon substrate 110 is also provided with an ACF protective glue 203, which connects the side of the second ACF pad 201 and the side of the silicon substrate 110.

[0161] Optionally, when the side of the second copper foil layer 222 of the silicon substrate 110 is also covered with a first copper deposition layer 251, the ACF protective glue 203 is arranged on the side of the first copper deposition layer 251 facing the silicon substrate 110.

[0162] Specifically, after the second ACF pad 201 is connected to the first ACF pad 101 of the silicon substrate 110 through the ACF adhesive layer 202, in order to protect the ACF bonding area, dispensing can be performed on the side of the silicon substrate 110 close to the first ACF pad 101 to form the ACF protective adhesive 203. The ACF protective adhesive 203 can cover at least part of the side of the silicon substrate 110, the second ACF pad 201, and the side of the ACF adhesive layer 202, thereby playing a good protection role on the ACF bonding area. Further, the solidified ACF protective adhesive 203 can also play a certain supporting role on the area where the flexible circuit board 200 is located at the edge of the silicon substrate 110, thereby improving the stability of the flexible circuit board 200 under the display screen 20.

[0163] Referring back to Figure 8 and Figure 9 , in the flexible circuit board 200 provided in the embodiments of the present application, the side of the flexible substrate layer 210 facing the ultrasonic fingerprint sensor chip 100 further comprises a first transmission area 233 for transmitting electrical signals of the flexible circuit board 200. The first transmission area 233 is located on the side of the ACF pressing area 232 away from the chip bonding area 231, and the first transmission area 233 is provided with a second copper foil layer 222 and a first insulating layer 241 covering the second copper foil layer 222.

[0164] Specifically, in the embodiments of the present application, the flexible circuit board 200 comprises a first transmission area 233 for transmitting electrical signals thereof, and the flexible circuit board 200 can be electrically connected to external electrical devices through the first transmission area 233. Electrical devices such as capacitors and resistors can also be provided in the first transmission area 233 to process electrical signals accordingly.

[0165] The first transmission area 233 is provided with a second copper foil layer 222 extending from the ACF pressing area 232, and the second copper foil layer 222 is covered with a first insulating layer 241, which can be used to protect the second copper foil layer 222.

[0166] Optionally, as shown in Figure 8 and Figure 9 , in some embodiments, the first transmission area 233 is further provided with a first copper deposition layer 251 extending from the ACF pressing area 232, and the first copper deposition layer 251 and the second copper foil layer 222 together form a circuit trace layer covering the ACF pressing area 232 and the first transmission area 233, so as to facilitate signal transmission of the flexible circuit board 200. In this case, the first insulating layer 241 covers the first copper deposition layer 251 and the second copper foil layer 222, and can protect both the first copper deposition layer 251 and the second copper foil layer 222.

[0167] Referring back to Figure 8and Figure 9 As shown in some embodiments, the side of the flexible substrate layer 210 facing away from the ultrasonic fingerprint sensor chip 100 includes a second transmission area 234 corresponding to the first transmission area 233 described above, which is also used to transmit electrical signals of the flexible circuit board 200, and the second transmission area 234 is provided with a third copper foil layer 223 and a second insulating layer 242 covering the third copper foil layer 223.

[0168] Specifically, in this embodiment, the flexible circuit board 200 includes a first transmission area 233 and a second transmission area 234 for transmitting electrical signals thereof, and the first transmission area 233 and the second transmission area 234 are distributed on the upper and lower surfaces of the flexible substrate layer 210 and can at least partially coincide in the thickness direction of the flexible substrate layer 210.

[0169] The distribution of the laminated layers in the second transmission area 234 can be the same as that in the first transmission area 233. As an example, as shown in Figure 8 and Figure 9 The second transmission area 234 is provided with a third copper foil layer 223, a second copper sinking layer 252, and a second insulating layer 242. The second transmission area 234 can improve the circuit trace area in the flexible circuit board 200, thereby facilitating the flexible circuit board 200 to better transmit and process the related signals of the ultrasonic fingerprint sensor chip 100.

[0170] Figure 10 Another schematic structural diagram of the ultrasonic fingerprint identification device 10 provided by the embodiments of the present application is shown.

[0171] As shown in Figure 10 The side of the flexible substrate layer 210 facing away from the ultrasonic fingerprint sensor chip 100 includes a display screen bonding area 235 corresponding to the chip bonding area 231 and the ACF compression area 232, and the first connecting layer 310 in the connecting medium layer 300 is arranged in the display screen bonding area 235.

[0172] Specifically, in the embodiments of the present application, when the flexible substrate layer 210 is installed under the display screen 20, it can be connected to the display screen 20 through the first connecting layer 310 arranged in the display screen bonding area 235. The display screen bonding area 235 is arranged corresponding to the chip bonding area 231 and the ACF compression area 232, that is, in the direction perpendicular to the display screen 20, the display screen bonding area 235 at least partially coincides with the chip bonding area 231, and the display screen bonding area 235 at least partially coincides with the ACF compression area 232.

[0173] By setting the first connection layer 310 at the display screen bonding area 235 corresponding to the chip bonding area 231 and the ACF compression area 232 to connect the ultrasonic fingerprint sensor chip 100 and the display screen 20, the overall connection reliability of the ultrasonic fingerprint sensor chip 100 and the display screen 20 can be improved, thereby ensuring the use reliability of the ultrasonic fingerprint identification device 10.

[0174] In some possible embodiments, the display screen bonding area 235 can cover the chip bonding area 231 and the ACF compression area 232. Specifically, the chip bonding area 231 and the ACF compression area 232 can be completely located in the projection of the display screen bonding area 235 in the direction perpendicular to the display screen 20. By the technical solution of this embodiment, the overall connection reliability of the ultrasonic fingerprint sensor chip 100 and the display screen 20 can be more fully ensured, thereby ensuring the use reliability of the ultrasonic fingerprint identification device 10.

[0175] Figure 11 Another schematic structural diagram of the ultrasonic fingerprint identification device 10 provided by the embodiment of the present application is shown.

[0176] As shown in Figure 11 In the embodiment of the present application, the flexible circuit board 200 and the connection medium layer 300 are two separate components. The connection medium layer 300 is connected between the piezoelectric transducer 120 and the display screen 20, and the first end of the flexible circuit board 200 is provided with the second ACF pad 201. The first end of the flexible circuit board 200 is arranged side by side with the piezoelectric transducer 120 on the silicon substrate 110, and the connection medium layer 300 is used to provide a containing space for the first end of the flexible circuit board 200 between the silicon substrate 110 and the display screen 20.

[0177] Specifically, in this embodiment, after the piezoelectric transducer 120 is connected to the display screen 20 through the connection medium layer 300, the thickness space of the piezoelectric transducer 120 and the connection medium layer 300 can provide a containing space between the display screen 20 and the silicon substrate 110. Therefore, the first end of the flexible circuit board 200 provided with the second ACF pad 201 can be arranged between the display screen 20 and the silicon substrate 110 by using the space and connected to the first ACF pad 101 on the upper surface of the silicon substrate 110.

[0178] By the technical solution of this embodiment, the installation space required by the flexible circuit board 200 under the display screen 20 can be saved, the overall thickness of the ultrasonic fingerprint identification device 10 is reduced, thereby facilitating the installation of the ultrasonic fingerprint identification device 10 under the display screen 20.

[0179] Continuing to refer to Figure 11As shown in the embodiment of this application, the first end of the flexible circuit board 200 includes: a fourth copper foil layer 224 and a third insulating layer 243. The second ACF pad 201 is disposed on the side of the fourth copper foil layer 224 facing the silicon substrate 110, and the third insulating layer 243 is disposed on the side of the fourth copper foil layer 224 away from the silicon substrate 110 and covers the fourth copper foil layer 224.

[0180] Specifically, the first end of the flexible circuit board 200 with the second ACF pad 201 includes a fourth copper foil layer 224 and a third insulating layer 243. The thickness of the two-layer stacked structure can be small, so that it can be easily accommodated between the display screen 20 and the silicon substrate 110.

[0181] Optionally, a third copper plating layer 253 may be provided between the fourth copper foil layer 224 and the third insulating layer 243. The third copper plating layer 253 and the fourth copper foil layer 224 can together form a circuit trace layer. The third insulating layer 243 covers the third copper plating layer 253 and the fourth copper foil layer 224 to provide insulation protection for the two metal layers.

[0182] Furthermore, in some implementations, such as Figure 11 As shown, the second end of the flexible circuit board 200 opposite to the first end is the transmission end of the flexible circuit board 200. The second end of the flexible circuit board 200 includes: a flexible substrate layer 210, a fourth copper foil layer 224 and a third insulating layer 243 disposed on the side of the flexible substrate layer 210 facing the display screen 20, and a fifth copper foil layer 225 and a fourth insulating layer 244 disposed on the side of the flexible substrate layer 210 away from the display screen 20.

[0183] Specifically, in this embodiment, the second end of the flexible circuit board 200 can be connected to an external electrical device to transmit the relevant electrical signals of the ultrasonic fingerprint recognition device 10. The second end of the flexible circuit board 200 may include a flexible substrate layer 210 and copper foil layers and insulating layers disposed on the upper and lower surfaces of the flexible substrate layer 210. The fourth copper foil layer 224 and the third insulating layer 243 disposed on the upper surface of the flexible substrate layer 210 may extend from the first end of the flexible circuit board 200. The flexible substrate layer 210 can be used to support and reinforce the flexible circuit board 200, facilitating its installation in electronic devices. Furthermore, the copper foil layers on the upper and lower surfaces of the flexible substrate layer 210 can improve the electrical signal transmission performance of the flexible circuit board 200.

[0184] Optionally, similar to the third copper deposition layer 253 between the fourth copper foil layer 224 and the third insulating layer 243, a fourth copper deposition layer 254 can also be arranged between the fifth copper foil layer 225 and the fourth insulating layer 244, and the fourth copper deposition layer 254 can form a circuit trace layer together with the fifth copper foil layer 225, and the fourth insulating layer 244 covers the fourth copper deposition layer 254 and the fifth copper foil layer 225 to provide insulation protection for the two metal layers.

[0185] Continuing to refer to Figure 11 In the embodiment, the side of the fourth copper foil layer 224 facing the silicon substrate 110 at the first end of the flexible circuit board 200 is further provided with an ACF protective glue 203, which connects the side of the second ACF pad 201 and the side of the silicon substrate 110.

[0186] Specifically, after the second ACF pad 201 is connected to the first ACF pad 101 of the silicon substrate 110 through the ACF glue layer 202, in order to protect the ACF welding area, glue can be dispensed on the side of the silicon substrate 110 close to the first ACF pad 101 to form the ACF protective glue 203. The ACF protective glue 203 can cover at least part of the side of the silicon substrate 110, the side of the second ACF pad 201 and the side of the ACF glue layer 202, thereby providing good protection for the ACF welding area. Further, the solidified ACF protective glue 203 can also provide certain support for the first end of the flexible circuit board 200, thereby improving the stability of the flexible circuit board 200 under the display screen 20.

[0187] Optionally, similar to the above Figure 9 described embodiment, in the Figure 11 described embodiment, the side of the silicon substrate 110 of the ultrasonic fingerprint sensor chip 100 facing the display screen 20 (the upper surface of the silicon substrate 110 shown in the figure) includes an effective recognition area, and the piezoelectric transducer 120 is arranged in the effective recognition area 115, and the edge of the connection medium layer 300 exceeds the edge of the effective recognition area 115.

[0188] Specifically, the related scheme of the effective recognition area can refer to the related description of the above Figure 9 described embodiment. In order to ensure the transmission of the ultrasonic signal of the ultrasonic fingerprint sensor chip 100 by the connection medium layer 300, the edge of the connection medium layer 300 exceeds the edge of the effective recognition area in the silicon substrate 110, preventing the installation process and the manufacturing process from affecting the connection medium layer 300 and causing the connection medium layer 300 to not completely cover the effective recognition area. As an example, the edge of the connection medium layer 300 can exceed the edge of the effective recognition area by more than 0.05mm.

[0189] Further, in order to more effectively guarantee the transmission of the connection medium layer 300 to the ultrasonic wave signal, the edge of the connection medium layer 300 can exceed the edge of the piezoelectric transducer 120, for example, the edge of the connection medium layer 300 can exceed the edge of the piezoelectric transducer 120 by more than 0.05mm.

[0190] Figure 12 and Figure 13 Another two schematic structural diagrams of the ultrasonic fingerprint identification device 10 provided by the embodiments of the present application are shown.

[0191] In Figure 12 the embodiments shown, part of the laminated layers in the flexible circuit board 200 can be reused as part of the laminated layers in the connection medium layer 300. Specifically, the technical solutions of reusing the flexible circuit board 200 as the connection medium layer 300 can refer to the technical solutions of the embodiments shown in Figure 7 to Figure 10 , which will not be described in detail here. In Figure 13 the embodiments shown, the flexible circuit board 200 and the connection medium layer 300 are two separate components. Specifically, the related technical solutions of the flexible circuit board 200 and the connection medium layer 300 can refer to the technical solutions of the embodiments shown in Figure 11 , which will not be described in detail here.

[0192] As shown in Figure 12 and Figure 13 , in the embodiments of the present application, the edge of at least part of the laminated layers in the connection medium layer 300 exceeds the edge of the silicon substrate 110, and the ultrasonic fingerprint identification device 10 further comprises a fixing glue 400, which is arranged in the edge area of at least part of the laminated layers in the connection medium layer 300, and surrounds and covers at least part of the side surface of the ultrasonic fingerprint sensor chip 100.

[0193] As an example, in the embodiments shown in Figure 12 and Figure 13 , in the direction parallel to the display screen 20, the first connection layer 310 in the connection medium layer 300 exceeds the edge of the silicon substrate 110. The fixing glue 400 is arranged on the lower surface of the first connection layer 310 and surrounds the edge area of the first connection layer 310. At the same time, the fixing glue 400 also surrounds at least part of the side surface of the ultrasonic fingerprint sensor chip 100, that is, the fixing glue 400 surrounds at least part of the side surface of the silicon substrate 110 of the ultrasonic fingerprint sensor chip 100 and at least part of the side surface of the piezoelectric transducer 120, thereby fixing the ultrasonic fingerprint sensor chip 100 to the first connection layer 310. Wherein, the side surface of the ultrasonic fingerprint sensor chip 100 is perpendicular to the display screen 20.

[0194] In the technical solution of the embodiment of the present application, the fixing adhesive 400 is arranged, so that the connection reliability of the ultrasonic fingerprint sensor chip 100 and the at least partially laminated connection medium layer 300 is improved, and the connection reliability of the ultrasonic fingerprint identification device 10 under the display screen 20 is further improved. In addition, since the fixing adhesive 400 is arranged in the at least partially laminated connection medium layer 300, the fixing adhesive 400 does not directly contact the display screen 20, so that when the ultrasonic fingerprint identification device 10 is disassembled for rework, the processing of the fixing adhesive 400 will not affect the display screen 20. Therefore, by using the technical solution of the embodiment, the ultrasonic fingerprint identification device 10 under the display screen 20 can be conveniently reworked.

[0195] Optionally, the fixing adhesive 400 can be ultraviolet light curing adhesive (which can be referred to as UV curing adhesive for short), and the fixing adhesive 400 can be cured by ultraviolet light curing or ultraviolet light and humidity curing. Alternatively, the fixing adhesive 400 can also be an adhesive layer cured at low temperature (less than or equal to 100°C), which can also be referred to as a heat curing adhesive. The UV curing adhesive or heat curing adhesive can be, for example, an epoxy resin material. By curing the fixing adhesive 400 in the above-mentioned ways, the influence of high-temperature curing on the display screen 20 and the ultrasonic fingerprint identification device 10 can be avoided. In addition, the curing shrinkage rate of the fixing adhesive 400 can be or equal to 3%, so as to ensure the fixing effect of the fixing adhesive 400 on the ultrasonic fingerprint identification device 10.

[0196] Optionally, in some embodiments, the edge of the at least partially laminated connection medium layer 300 exceeds the edge of the silicon substrate 110 by more than 0.5 mm, for example, in the embodiments shown in Figure 12 and Figure 13 , the distance between the edge of the first connection layer 310 and the edge of the silicon substrate 110 is greater than or equal to 0.5 mm.

[0197] By using the technical solution of the embodiment, even if the connection medium layer 300 and / or the silicon substrate 110 has manufacturing or installation tolerance, the fixing adhesive 400 can effectively connect the connection medium layer 300 and the silicon substrate 110, so as to ensure the installation reliability of the ultrasonic fingerprint identification device 10 under the display screen 20. In addition, the at least partially laminated connection medium layer 300 can also completely cover the silicon substrate 110, so as to prevent the ultrasonic fingerprint sensor chip 100 on which the silicon substrate 110 is located from being observed by a user through the display screen 20, and to improve the appearance of the display screen 20.

[0198] Optionally, in addition to the above Figure 12 and Figure 13In addition to the technical solution that the edge of the first connecting layer 310 in the connecting medium layer 300 exceeds the edge of the silicon substrate 110 in the illustrated embodiment, in other alternative embodiments, the edges of multiple layers of the stack in the connecting medium layer 300 can also exceed the edge of the silicon substrate 110, for example, the first connecting layer 310 and the medium layer 330 exceed the edge of the silicon substrate 110, or all the layers in the connecting medium layer 300 exceed the edge of the silicon substrate 110.

[0199] In some cases, when the ultrasonic fingerprint identification device 10 is arranged below the light-transmitting layer of the display screen 20, in order to further improve the appearance problem caused by arranging the ultrasonic fingerprint sensor chip 100 below the display screen 20, the ultrasonic fingerprint identification device 10 can further include a light-blocking adhesive 500.

[0200] Continuing to refer to Figure 12 and Figure 13 In the embodiments of the present application, the ultrasonic fingerprint identification device 10 can further include a light-blocking adhesive 500 arranged on the display screen 20 and surrounding at least part of the layers in the connecting medium layer 300. For example, the light-blocking adhesive 500 can surround the first connecting layer 310.

[0201] Specifically, the light-blocking adhesive 500 can be a black adhesive layer to play a better light-blocking role. Further, the light-blocking adhesive 500 surrounds at least part of the layers in the connecting medium layer 300, and the whole of the connecting medium layer 300 and the light-blocking adhesive 500 can further better cover the ultrasonic fingerprint sensor chip 100 on which the silicon substrate 110 is located, thereby more reliably solving the appearance problem caused by arranging the ultrasonic fingerprint identification device 10 below the transparent layer of the display screen 20.

[0202] Optionally, in order to ensure the light-blocking effect of the light-blocking adhesive 500, the width of the light-blocking adhesive 500 can be greater than or equal to 0.1 mm, and / or the light-blocking adhesive 500 has an absorption rate of visible light greater than or equal to 70%, for example, the light-blocking adhesive 500 has an absorption rate of visible light between 70% and 90%.

[0203] Optionally, the light-blocking adhesive can be a pressure sensitive adhesive (PSA), a UV-cured adhesive, a heat-cured adhesive, a UV-cured adhesive, or a thermoplastic ink, etc. Among them, the heat-cured adhesive and the UV-cured adhesive can be, for example, an epoxy resin material.

[0204] Figure 14 shows Figure 12 and Figure 13 A schematic top view of the ultrasonic fingerprint identification device 10 in the illustrated embodiment.

[0205] As Figure 14As shown, the silicon substrate 110 can be a rectangular substrate, and the first interconnect layer 310 can also be rectangular. The area of ​​the first interconnect layer 310 can be larger than the area of ​​the silicon substrate 110, and the first interconnect layer 310 can cover the silicon substrate 110. The length direction of the first interconnect layer 310 is the same as the length direction of the silicon substrate 110, and the width direction of the first interconnect layer 310 is the same as the width direction of the silicon substrate 110.

[0206] Along the length direction L of the silicon substrate 110 and the first interconnect layer 310, the distance D1 between the first interconnect layer 310 and the silicon substrate 110 is greater than or equal to 0.5 mm. Similarly, along the width direction W of the silicon substrate 110 and the first interconnect layer 310, the distance D2 between the first interconnect layer 310 and the silicon substrate 110 is greater than or equal to 0.5 mm.

[0207] Furthermore, since both the silicon substrate 110 and the first connecting layer 310 are rectangular, the fixing adhesive 400 and the light-shielding adhesive 500 can both be frame-shaped adhesive layers. The light-shielding adhesive 500 is disposed around the perimeter of the first connecting layer 310, and its width D3 is greater than or equal to 0.1 mm. The fixing adhesive 400 is disposed around the silicon substrate 110, and it may have notches to avoid obstructing the flexible circuit board 200 electrically connected to the silicon substrate 110.

[0208] Figure 15 and Figure 16 Two other schematic structural diagrams of the ultrasonic fingerprint recognition device 10 provided in the embodiments of this application are shown.

[0209] exist Figure 15 In the illustrated embodiment, some layers in the flexible circuit board 200 can be reused as some layers in the connection dielectric layer 300. Specifically, the technical solution for reusing the flexible circuit board 200 as the connection dielectric layer 300 can be found above. Figure 7 to Figure 10 The technical solutions of the illustrated embodiments will not be described in detail here. Figure 16 In the illustrated embodiment, the flexible circuit board 200 and the connecting dielectric layer 300 are two separate components. Specifically, the relevant technical solutions for the flexible circuit board 200 and the connecting dielectric layer 300 can be found above. Figure 11 The technical solutions of the embodiments shown will not be described in detail here.

[0210] like Figure 15 and Figure 16As shown in the embodiments of the present application, at least part of the edges of the connecting medium layer 300 is flush with at least part of the edges of the silicon substrate 110 or at least part of the edges of the connecting medium layer 300 is recessed by less than or equal to 0.5 mm compared with at least part of the edges of the silicon substrate 110, the ultrasonic fingerprint identification device 10 further comprises a fixing adhesive 400, which is arranged on the display screen 20 and surrounds and covers at least part of the side surface of the connecting medium layer 300 and the ultrasonic fingerprint sensor chip 100.

[0211] As an example, in the embodiments shown in Figure 15 and Figure 16 , the fixing adhesive 400 is arranged on the lower surface of the display screen 20 and surrounds the side surface of the connecting medium layer 300. At the same time, the fixing adhesive 400 also surrounds the side surface of the ultrasonic fingerprint sensor chip 100. In the direction perpendicular to the display screen 20, the fixing adhesive 400 can cover at least part of the side surface of the connecting medium layer 300 and the ultrasonic fingerprint sensor chip 100, thereby fixing the ultrasonic fingerprint sensor chip 100 to the connecting medium layer 300 and the display screen 20.

[0212] Through the arrangement of the fixing adhesive 400, the connection reliability of the ultrasonic fingerprint sensor chip 100, the connecting medium layer 300 and the display screen 20 can be improved, and the connection reliability of the ultrasonic fingerprint identification device 10 under the display screen 20 is further improved. In addition, the fixing adhesive 400 is directly arranged on the lower surface of the display screen 20, and in some cases, the fixing adhesive 400 can be used as a shading adhesive to improve the appearance problem caused by the ultrasonic fingerprint identification device 10 under the display screen 20.

[0213] Optionally, in order to ensure the shading effect of the fixing adhesive 400 as a shading adhesive, the width of the fixing adhesive 400 can be greater than or equal to 0.1 mm.

[0214] Figure 17 A schematic top view of the ultrasonic fingerprint identification device 10 is shown in the embodiments shown in Figure 15 and Figure 16 .

[0215] Similar to the above Figure 14 , as shown in Figure 17 , the silicon substrate 110 can be a rectangular substrate, and the fixing adhesive 400 arranged around the silicon substrate 110 can be a frame type. In the length direction L and the width direction W of the silicon substrate 110, the width D3 of the fixing adhesive 400 can be greater than or equal to 0.1 mm.

[0216] In addition, in the embodiments shown in Figure 17In the illustrated embodiment, one side of the silicon substrate 110 with the first ACF pad 101 may correspond to the output end of the flexible circuit board 200. The adhesive 400 may have a notch to avoid the area where the output end of the flexible circuit board 200 is located. That is, the adhesive 400 may be disposed around other areas of the silicon substrate 110 except for the area where the output end of the flexible circuit board 200 is located.

[0217] Through the technical solutions of the above-mentioned application embodiments, the thickness of each layer in the ultrasonic fingerprint recognition device 10 can be controlled so that the overall thickness range of the ultrasonic fingerprint recognition device 10 is less than or equal to 500μm, thereby reducing the installation thickness space required for the ultrasonic fingerprint recognition device 10 below the display screen 20.

[0218] In some embodiments, the ultrasonic fingerprint recognition device 10 may be located below the non-folding screen, i.e., the aforementioned display screen 20 is a non-folding screen.

[0219] Figure 18 This illustration shows a schematic structural diagram of the ultrasonic fingerprint recognition device 10 provided in this application under a non-folding screen.

[0220] like Figure 18 As shown, the bottom layer of the non-foldable screen is a buffer layer 24, in which a buffer layer window 240 is formed. The ultrasonic fingerprint recognition device 10 is disposed in the buffer layer window 240 and is attached to the substrate layer 25 above the buffer layer 24 in the non-foldable screen through the connecting medium layer 300.

[0221] Optionally, the substrate layer 25 can be an organic material layer, for example, the substrate layer 25 can be PI, and other circuit layers and light-emitting layers of the display screen 20 are all fabricated on the substrate layer 25. A buffer layer 24 is disposed below the substrate layer 25, which may include a foam layer and a copper foil layer, etc., and is used to buffer, shield, and dissipate heat for the display screen 20.

[0222] In order to reduce the installation space of the ultrasonic fingerprint recognition device 10 under the non-folding screen, and in order to reduce the impact of the related stacking layers in the buffer layer 24 on the fingerprint recognition performance of the ultrasonic fingerprint recognition device 10, a buffer layer window 240 can be formed in the buffer layer 24. The ultrasonic fingerprint recognition device 10 is disposed in the buffer layer window 240 and connected to the substrate layer 25 through the connecting medium layer 300, thereby being installed below the display screen 20.

[0223] like Figure 18As shown, in this embodiment, the ultrasonic fingerprint recognition device 10 may include a fixing adhesive 400 and a light-shielding adhesive 500. The fixing adhesive 400 is disposed on the connecting medium layer 300 to fix and connect the ultrasonic fingerprint sensor chip 100 to the connecting medium layer 300. The light-shielding adhesive 500 is disposed on the display screen 20 to surround the connecting medium layer 300 and provide light shielding. Specifically, the relevant technical solutions of this ultrasonic fingerprint recognition device 10 can be found above. Figure 12 and Figure 14 The relevant descriptions of the embodiments shown will not be repeated here.

[0224] In this embodiment, in order to prevent the light signals of the ultrasonic fingerprint sensor chip 100 and flexible circuit board 200 from being observed by the user through the buffer layer window 240, the light-shielding adhesive 500 can be disposed in the buffer layer window 240 and located in the edge area of ​​the buffer layer window 240. The light-shielding adhesive 500 and the connecting medium layer 300 can completely fill the buffer layer window 240 to improve the appearance of the ultrasonic fingerprint recognition device 10 under the non-folding screen.

[0225] Figure 19 This illustration shows a schematic structural diagram of the ultrasonic fingerprint recognition device 10 provided in this application under a non-folding screen.

[0226] like Figure 19 As shown, in this embodiment, the ultrasonic fingerprint recognition device 10 may include a fixing adhesive 400, which is disposed on the display screen 20 to fix the ultrasonic fingerprint sensor chip 100 and the connection medium layer 300 to the display screen 20, and the fixing adhesive 400 is disposed around the connection medium layer 300 to provide a light-shielding function. Specifically, the relevant technical solutions of this ultrasonic fingerprint recognition device 10 can be found above. Figure 15 and Figure 17 The relevant descriptions of the embodiments shown will not be repeated here.

[0227] In this embodiment, in order to prevent the light signals of the ultrasonic fingerprint sensor chip 100 and flexible circuit board 200 from being observed by the user through the buffer layer window 240, the fixing adhesive 400 can be disposed in the buffer layer window 240 and located in the edge area of ​​the buffer layer window 240. The fixing adhesive 400 and the connecting medium layer 300 together can completely fill the buffer layer window 240 to improve the appearance problem of the ultrasonic fingerprint recognition device 10 under the non-folding screen.

[0228] Optionally, in the above Figure 18 and Figure 19 In the embodiment shown, the edge of the buffer layer window 240 may extend beyond the edge of the connecting medium layer 300 by more than 0.1 mm.

[0229] Specifically, in the case that the connecting medium layer 300 is rectangular, the buffer layer window 240 can also be a rectangular window that fits the connecting medium layer 300. The area of the buffer layer window 240 can be greater than the area of the connecting medium layer 300, and the edge of the buffer layer window 240 can exceed the edge of the connecting medium layer 300 by 0.1 mm or more, thereby facilitating the installation of the connecting medium layer 300 in the buffer layer window 240, and further facilitating the installation of the ultrasonic fingerprint identification device 10 in the buffer layer window 240 through the connecting medium layer 300.

[0230] Since there is a gap of 0.1 mm or more between the buffer layer window 240 and the connecting medium layer 300, the gap can be used to accommodate the light shielding glue 500 shown in Figure 18 or the fixing glue 400 shown in Figure 19 , so as to play a good light shielding role.

[0231] In other embodiments, the ultrasonic fingerprint identification device 10 can also be arranged under the folding screen, i.e., the display screen 20 is a folding screen.

[0232] Figure 20 and Figure 21 Two schematic structural diagrams of the ultrasonic fingerprint identification device 10 provided by the embodiments of the present application under the folding screen are shown.

[0233] As shown in Figure 20 and Figure 21 , the lowermost layer of the folding screen is a support layer 26, and the ultrasonic fingerprint identification device 10 is attached to the support layer 26 through the connecting medium layer 300. Optionally, the support layer 26 can be a support steel sheet or other high-strength support material.

[0234] Specifically, due to the special requirement of folding of the folding screen, the lowermost layer of the folding screen needs to be provided with a support layer 26, and the support layer 26 cannot be windowed, so as not to affect the folding performance of the folding screen. Therefore, in the case that the display screen 20 is a folding screen, the ultrasonic fingerprint identification device 10 in the embodiments of the present application can be directly connected to the bottom layer of the folding screen, i.e., connected to the support layer 26, through the connecting medium layer 300.

[0235] Since the support layer 26 is provided at the bottom layer of the folding screen, the ultrasonic fingerprint identification device 10 arranged under the display screen 20 does not need to consider the appearance problem. As shown in Figure 20 , in the case that the edge of the connecting medium layer 300 exceeds the edge of the silicon substrate 110, the ultrasonic fingerprint identification device 10 can only include the fixing glue 400 without including the light shielding glue 500. The specific scheme of the ultrasonic fingerprint identification device 10 in this embodiment can be referred to the above Figure 12 and Figure 14Other descriptions besides the 500 light-blocking gel are not elaborated here.

[0236] like Figure 21 As shown, the ultrasonic fingerprint recognition device 10 can also be directly fixed to the support layer 26 using adhesive 400. For a detailed description of the ultrasonic fingerprint recognition device 10 in this embodiment, please refer to the above text. Figure 15 and Figure 17 The relevant descriptions in the text will not be elaborated upon here.

[0237] This application also provides an electronic device, including a display screen 20 and an ultrasonic fingerprint recognition device 10 as described in any of the above embodiments. The display screen provides a pressing interface for a user's finger and receives the pressure of the user's finger. The ultrasonic fingerprint recognition device 10 is disposed below the display screen 20 and is used to recognize the fingerprint of the user's finger pressed on the display screen 20.

[0238] Optionally, the electronic device may include, but is not limited to, mobile terminal devices, such as mobile phones, laptops, tablets, etc.

[0239] Optionally, the electronic device may also include a battery, which is also disposed below the display screen 20. In this embodiment, because the ultrasonic fingerprint recognition device 10 is relatively thin, it can be disposed between the battery and the display screen 20. This embodiment saves the installation space required for the ultrasonic fingerprint recognition device 10 in the electronic device.

[0240] In some embodiments, the display screen 20 can be a non-foldable screen, the bottom layer of which is a buffer layer with a buffer layer window formed therein. The ultrasonic fingerprint recognition device 10 is disposed in the buffer layer window and attached to the substrate layer above the buffer layer in the non-foldable screen.

[0241] Specifically, the relevant technologies of the non-foldable screen and the ultrasonic fingerprint recognition device 10 in this implementation scheme can be found above. Figure 18 and Figure 19 The technical solutions of the embodiments shown will not be described in detail here.

[0242] In other embodiments, the display screen 20 can be a foldable screen, with the bottom layer of the foldable screen being a support layer, and the ultrasonic fingerprint recognition device 10 is attached to the support layer.

[0243] Specifically, the relevant technologies of the foldable screen and the ultrasonic fingerprint recognition device 10 in this embodiment can be found above. Figure 20 and Figure 21 The technical solutions of the embodiments shown will not be described in detail here.

[0244] It should be understood that the specific example in the embodiments of the present application is only to help those skilled in the art to better understand the embodiments of the present application, and not to limit the scope of the embodiments of the present application.

[0245] For example, various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction, and in order to avoid unnecessary repetition, various possible combinations are not described again in the present application.

[0246] For another example, various different embodiments of the present application can also be combined in any manner, as long as it does not deviate from the idea of the present application, it should also be considered as disclosed in the present application.

[0247] It should be understood that the terms used in the embodiments of the present application and the appended claims are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present application. For example, the singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0248] Those of ordinary skill in the art can realize that the units of the examples described in conjunction with the embodiments disclosed herein can be realized in electronic hardware, computer software or a combination of both. In order to clearly illustrate the interchangeability of hardware and software, the components and steps of the examples have been described in general terms in the above description. Whether the functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0249] In several embodiments provided by the present application, it should be understood that the disclosed system and device can be implemented in other ways. For example, the above-described device embodiments are only schematic, and the division of the modules is only a logical function division, and actual implementation can have another division manner, for example, a plurality of modules or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the displayed or discussed each other can be indirect coupling or communication connection through some interfaces, devices or modules, and can also be electrical, mechanical or other forms of connection.

[0250] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An ultrasonic fingerprint recognition device, characterized in that, The ultrasonic fingerprint recognition device, located beneath the display screen of an electronic device to enable under-display ultrasonic fingerprint recognition, includes: An ultrasonic fingerprint sensor chip includes: a silicon substrate and a piezoelectric transducer disposed on the silicon substrate, wherein the piezoelectric transducer includes a piezoelectric layer, an upper electrode located above the piezoelectric layer, and a lower electrode located below the piezoelectric layer. The piezoelectric transducer is used to emit ultrasonic signals to a finger pressed on the display screen and to receive ultrasonic fingerprint signals returned by the finger. The silicon substrate includes a circuit unit and a first anisotropic conductive adhesive (ACF) pad. The circuit unit is electrically connected to the first ACF pad and electrically connected to the upper electrode and the lower electrode to control the piezoelectric transducer to generate the ultrasonic signals and to detect the ultrasonic fingerprint signals for fingerprint recognition. The flexible circuit board includes a second ACF pad, which is pressed and connected to the first ACF pad to realize the electrical connection between the ultrasonic fingerprint sensor chip and the flexible circuit board. A connecting medium layer is connected between the piezoelectric transducer of the ultrasonic fingerprint sensor chip and the display screen. The connecting medium layer is used to transmit the ultrasonic signal generated by the piezoelectric transducer to the display screen and the ultrasonic fingerprint signal to the piezoelectric transducer. The circuit unit includes a chip pad, and a redistribution layer RDL connected to the chip pad is disposed on the surface of the silicon substrate. The first ACF pad is a pad disposed on the RDL, and / or, a top layer trace connected to the chip pad is disposed inside the silicon substrate, and the first ACF pad is a pad disposed on the top layer trace.

2. The ultrasonic fingerprint recognition device according to claim 1, characterized in that, The thickness of the silicon substrate is between 50 μm and 300 μm.

3. The ultrasonic fingerprint recognition device according to claim 1, characterized in that, The piezoelectric layer is made of polyvinylidene fluoride (PVDF) or polyvinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE), and the thickness of the piezoelectric layer is between 4 μm and 40 μm.

4. The ultrasonic fingerprint recognition device according to claim 1, characterized in that, The thickness of the RDL is between 1 μm and 10 μm.

5. The ultrasonic fingerprint recognition device according to claim 1, characterized in that, The surface of the chip pad is coated with a gold layer, or the surface of the chip pad is an air layer, or the surface of the chip pad is provided with an insulating layer.

6. The ultrasonic fingerprint recognition device according to claim 1, characterized in that, The ultrasonic fingerprint recognition device includes: a plurality of first ACF pads arranged side by side along one side of the silicon substrate, wherein the plurality of first ACF pads satisfy at least one of the following conditions: The center distance between two adjacent first ACF pads in the plurality of first ACF pads is between 50 μm and 300 μm; The length of each of the plurality of first ACF pads is greater than or equal to 30 μm; The width of each of the plurality of first ACF pads is greater than or equal to 10 μm; The distance between each of the plurality of first ACF pads and the edge of the silicon substrate is greater than or equal to 10 μm.

7. The ultrasonic fingerprint recognition device according to any one of claims 1 to 6, characterized in that, The connection medium layer includes: a medium layer, a first connection layer and a second connection layer, wherein the first connection layer is connected to the display screen and the medium layer, and the second connection layer is connected to the medium layer and the piezoelectric transducer of the ultrasonic fingerprint sensor chip; The medium layer is made of organic polymer material, and / or the thickness of the medium layer is between 10 μm and 200 μm.

8. The ultrasonic fingerprint recognition device according to claim 7, characterized in that, The first connection layer has a first metal layer, and the second connection layer has a second metal layer; The thickness of the first metal layer and / or the second metal layer is between 3 μm and 30 μm.

9. The ultrasonic fingerprint recognition device according to claim 8, characterized in that, The first connecting layer is further provided with a first adhesive layer, which is used to connect the first metal layer and the display screen. The first adhesive layer has a visible light absorption rate of more than 70%, and the thickness of the first adhesive layer is between 3 μm and 30 μm.

10. The ultrasonic fingerprint recognition device according to claim 8, characterized in that, The second connecting layer also includes a second adhesive layer, which is used to connect the second metal layer to the piezoelectric transducer. The thickness of the second adhesive layer is between 3 μm and 30 μm.

11. The ultrasonic fingerprint recognition device according to claim 7, characterized in that, The flexible circuit board is disposed between the piezoelectric transducer and the display screen, and the flexible substrate layer in the flexible circuit board is reused as the dielectric layer in the connecting dielectric layer.

12. The ultrasonic fingerprint recognition device according to claim 11, characterized in that, The side of the flexible substrate layer facing the ultrasonic fingerprint sensor chip includes: a chip bonding area and an ACF pressing area; The chip bonding area is provided with a first copper foil layer and a chip adhesive layer, and the first copper foil layer and the chip adhesive layer are reused as the second connection layer in the connection medium layer; The ACF lamination area is provided with a second copper foil layer and a second ACF pad electrically connected to the second copper foil layer.

13. The ultrasonic fingerprint recognition device according to claim 12, characterized in that, The second copper foil layer is further provided with an ACF protective adhesive on the side facing the silicon substrate, and the ACF protective adhesive connects the side of the second ACF pad and the side of the silicon substrate.

14. The ultrasonic fingerprint recognition device according to claim 12, characterized in that, The side of the silicon substrate facing the flexible circuit board in the ultrasonic fingerprint sensor chip includes an effective recognition area, the piezoelectric transducer is disposed in the effective recognition area, and the edge of the chip bonding area extends beyond the edge of the effective recognition area.

15. The ultrasonic fingerprint recognition device according to claim 14, characterized in that, The edge of the chip bonding area extends more than 0.05 mm beyond the edge of the effective recognition area.

16. The ultrasonic fingerprint recognition device according to claim 12, characterized in that, The flexible substrate layer facing the ultrasonic fingerprint sensor chip further includes a first transmission area for transmitting electrical signals of the flexible circuit board. The first transmission area is located on the side of the ACF bonding area away from the chip bonding area, and the first transmission area is provided with a second copper foil layer and a first insulating layer covering the second copper foil layer.

17. The ultrasonic fingerprint recognition device according to claim 16, characterized in that, The side of the flexible substrate layer facing away from the ultrasonic fingerprint sensor chip includes: a second transmission area corresponding to the first transmission area, used to transmit electrical signals of the flexible circuit board; the second transmission area is provided with a third copper foil layer and a second insulating layer covering the third copper foil layer.

18. The ultrasonic fingerprint recognition device according to claim 12, characterized in that, The side of the flexible substrate layer facing away from the ultrasonic fingerprint sensor chip includes a display bonding area corresponding to the chip bonding area and the ACF bonding area, wherein the first connecting layer is disposed in the display bonding area.

19. The ultrasonic fingerprint recognition device according to claim 18, characterized in that, The display screen bonding area covers the chip bonding area and the ACF pressing area.

20. The ultrasonic fingerprint recognition device according to any one of claims 1 to 6, characterized in that, The first end of the flexible circuit board is provided with the second ACF pad, and the first end of the flexible circuit board and the piezoelectric transducer are arranged side by side on the silicon substrate. The connection dielectric layer is used to provide a accommodating space for the first end of the flexible circuit board between the silicon substrate and the display screen.

21. The ultrasonic fingerprint recognition device according to claim 20, characterized in that, The first end of the flexible circuit board includes a fourth copper foil layer and a third insulating layer. The second ACF pad is disposed on the side of the fourth copper foil layer facing the silicon substrate, and the third insulating layer is disposed on the side of the fourth copper foil layer away from the silicon substrate and covers the fourth copper foil layer.

22. The ultrasonic fingerprint recognition device according to claim 21, characterized in that, The fourth copper foil layer is further provided with an ACF protective adhesive on the side facing the silicon substrate, and the ACF protective adhesive connects the side of the second ACF pad and the side of the silicon substrate.

23. The ultrasonic fingerprint recognition device according to claim 21, characterized in that, The second end of the flexible circuit board, which is opposite to the first end, is the transmission end of the flexible circuit board. The second end of the flexible circuit board includes: a flexible substrate layer, a fourth copper foil layer disposed on the side of the flexible substrate layer facing the display screen, a third insulating layer, a fifth copper foil layer disposed on the side of the flexible substrate layer away from the display screen, and a fourth insulating layer.

24. The ultrasonic fingerprint recognition device according to claim 20, characterized in that, The side of the silicon substrate facing the display screen in the ultrasonic fingerprint sensor chip includes an effective recognition area, the piezoelectric transducer is disposed in the effective recognition area, and the edge of the connecting medium layer extends beyond the edge of the effective recognition area.

25. The ultrasonic fingerprint recognition device according to claim 24, characterized in that, The edge of the connecting medium layer extends more than 0.05 mm beyond the edge of the effective identification area.

26. The ultrasonic fingerprint recognition device according to any one of claims 1 to 6, characterized in that, At least a portion of the stacked layers in the interconnect dielectric layer have edges that extend beyond the edge of the silicon substrate; The ultrasonic fingerprint recognition device further includes: a fixing adhesive, which is disposed in the edge region of at least a portion of the stacked layers in the connecting medium layer, and surrounds the ultrasonic fingerprint sensor chip and covers at least a portion of the side surface of the ultrasonic fingerprint sensor chip.

27. The ultrasonic fingerprint recognition device according to claim 26, characterized in that, At least some of the stacked layers in the connection dielectric layer extend beyond the edge of the silicon substrate by more than 0.5 mm.

28. The ultrasonic fingerprint recognition device according to claim 26, characterized in that, At least the edge of the first interconnect layer in the interconnect dielectric layer extends beyond the edge of the silicon substrate.

29. The ultrasonic fingerprint recognition device according to claim 26, characterized in that, The ultrasonic fingerprint recognition device further includes: a light-shielding adhesive, which is disposed on the display screen and surrounds at least a portion of the stacked layers in the connecting medium layer.

30. The ultrasonic fingerprint recognition device according to claim 29, characterized in that, The width of the light-shielding adhesive is greater than or equal to 0.1 mm, and / or the light-shielding adhesive has an absorption rate of visible light greater than or equal to 70%.

31. The ultrasonic fingerprint recognition device according to any one of claims 1 to 6, characterized in that, At least a portion of the edge of the connecting dielectric layer is flush with at least a portion of the edge of the silicon substrate, or at least a portion of the edge of the connecting dielectric layer is recessed within 0.5 mm compared to at least a portion of the edge of the silicon substrate; The ultrasonic fingerprint recognition device further includes: a fixing adhesive, which is disposed on the display screen and surrounds the connection medium layer and the ultrasonic fingerprint sensor chip, and covers at least a portion of the sides of the connection medium layer and the ultrasonic fingerprint sensor chip.

32. The ultrasonic fingerprint recognition device according to claim 31, characterized in that, The width of the fixing adhesive is greater than or equal to 0.1 mm.

33. The ultrasonic fingerprint recognition device according to any one of claims 1 to 6, characterized in that, The thickness of the ultrasonic fingerprint recognition device is less than or equal to 500 μm.

34. The ultrasonic fingerprint recognition device according to any one of claims 1 to 6, characterized in that, The display screen is a non-foldable screen, and the bottom layer of the non-foldable screen is a buffer layer. A buffer layer window is formed in the buffer layer. The ultrasonic fingerprint recognition device is disposed in the buffer layer window and is attached to the substrate layer above the buffer layer in the non-foldable screen through the connecting medium layer.

35. The ultrasonic fingerprint recognition device according to claim 34, characterized in that, The edge of the buffer layer window extends more than 0.1 mm beyond the edge of the connecting medium layer.

36. The ultrasonic fingerprint recognition device according to any one of claims 1 to 6, characterized in that, The display screen is a foldable screen, and the bottom layer of the foldable screen is a support layer. The ultrasonic fingerprint recognition device is attached to the support layer through the connecting medium layer.

37. An electronic device, characterized in that, include: The display screen, and the ultrasonic fingerprint recognition device as described in any one of claims 1 to 33; The display screen is used to provide a finger pressing interface and to receive the finger pressing. The ultrasonic fingerprint recognition device is located below the display screen and is used to recognize the fingerprint of the finger pressed on the display screen.

38. The electronic device according to claim 37, characterized in that, The display screen is a non-foldable screen, and the bottom layer of the non-foldable screen is a buffer layer. A buffer layer window is formed in the buffer layer, and the ultrasonic fingerprint recognition device is disposed in the buffer layer window and attached to the substrate layer of the non-foldable screen located above the buffer layer.

39. The electronic device according to claim 37, characterized in that, The display screen is a foldable screen, and the bottom layer of the foldable screen is a support layer, on which the ultrasonic fingerprint recognition device is attached.

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