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 first flexible circuit board arranged between the ultrasonic fingerprint sensor chip and the display screen and connected to the first ACF pad of the ultrasonic fingerprint sensor chip through a second ACF pad; a second flexible circuit board arranged below the first flexible circuit board and connected to a third ACF pad of the first flexible circuit board through a fourth ACF pad; and a connecting medium layer connected between the piezoelectric transducer of the ultrasonic fingerprint sensor chip and the display screen.

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 factors such as flexible screen scheme, 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] The 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, which comprises a silicon substrate and a piezoelectric transducer arranged on the silicon substrate. The piezoelectric transducer comprises a piezoelectric layer, an upper electrode arranged above the piezoelectric layer, and a lower electrode arranged below the piezoelectric layer. The piezoelectric transducer is configured 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 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 first flexible circuit board is arranged between the ultrasonic fingerprint sensor chip and the display screen. The first flexible circuit board comprises a second ACF pad and a third ACF pad. The first flexible circuit board is connected to the first ACF pad of the ultrasonic fingerprint sensor chip through the second ACF pad to realize electrical connection between the ultrasonic fingerprint sensor chip and the first flexible circuit board. A second flexible circuit board is arranged below the first flexible circuit board and arranged side by side with the silicon substrate of the ultrasonic fingerprint sensor chip. The second flexible circuit board comprises a fourth ACF pad. The second flexible circuit board is connected to the third ACF pad of the first flexible circuit board through the fourth ACF pad to realize electrical connection between the first flexible circuit board and the second 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 configured 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 the technical scheme of the embodiments of the present application, an ultrasonic fingerprint identification device is provided, which comprises an ultrasonic fingerprint sensor chip, a first flexible circuit board, a second flexible circuit board, and a connecting medium layer. The ultrasonic fingerprint sensor chip, the first flexible circuit board, and the second flexible circuit board can be ACF packaged, which has high reliability and small thickness, and is beneficial to improve the reliability of the ultrasonic fingerprint identification device and reduce the installation space of the ultrasonic fingerprint identification device below the display screen. Further, the first flexible circuit board is arranged between the display screen and the ultrasonic fingerprint sensor chip, and the second flexible circuit board is arranged below the first flexible circuit board and arranged side by side with the ultrasonic fingerprint sensor chip. The ultrasonic fingerprint sensor chip and the first flexible circuit board can transmit electrical signals to the outside through the second flexible circuit board. The connection mode of the two flexible circuit boards not only reduces the risk of interference with the display screen, but also is beneficial to further save the installation space of the two flexible circuit boards below the display screen.

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

[0008] In some possible implementation manners, 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 implementation manners, 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 implementation manners, the thickness of the RDL is between 1 μm and 10 μm.

[0011] In some possible implementation manners, 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 implementation manners, 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 implementation manners, 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 any 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 from each first ACF pad in the plurality of first ACF pads to the edge of the silicon substrate is greater than or equal to 10 μm.

[0014] In some possible implementation manners, the connecting medium layer includes 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 further has a first adhesive layer arranged therein, and the first adhesive layer is configured to connect the first metal layer and the display screen, wherein the first adhesive layer has an absorption rate of visible light greater than 70%, and the first adhesive layer has a thickness of 3-30 microns.

[0017] In some possible implementation manners, the second connecting layer further has a second adhesive layer arranged therein, and the second adhesive layer is configured to connect the second metal layer and the piezoelectric transducer, and the second adhesive layer has a thickness of 3-30 microns.

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

[0019] In some possible implementation manners, one side of the first flexible substrate layer facing the ultrasonic fingerprint sensor chip comprises a chip bonding area and a first 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 a second connecting layer in the connecting medium layer; and the first 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 facing the silicon substrate is further provided with a first ACF protective adhesive, and the first ACF protective adhesive connects a side of the second ACF pad and a side of the silicon substrate.

[0021] In some possible implementation manners, one side of the silicon substrate in the ultrasonic fingerprint sensor chip facing the first flexible circuit board comprises an effective identification area, and the piezoelectric transducer is arranged in the effective identification area, and an edge of the chip bonding area exceeds an 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 implementation manners, one side of the first flexible substrate layer facing the ultrasonic fingerprint sensor chip further comprises a second ACF compression area, the second ACF compression area is located on a side of the first ACF compression area away from the chip bonding area, and the second ACF compression area is provided with a second copper foil layer and a third ACF pad electrically connected to the second copper foil layer.

[0024] In some possible implementation manners, the second flexible circuit board comprises a second flexible substrate layer, and one side of the second flexible substrate layer facing the display screen comprises a third ACF compression area corresponding to the second ACF compression area, the third ACF compression area is provided with a third copper foil layer and a fourth ACF pad electrically connected to the third copper foil layer.

[0025] In some possible implementation manners, in the first flexible circuit board, the second copper foil layer is further provided with a second ACF protective glue on a side facing the second flexible circuit board, and the second ACF protective glue connects the side of the third ACF pad, the side of the fourth ACF pad and the side of the second flexible circuit board.

[0026] In some possible implementation manners, in the second flexible circuit board, the third copper foil layer is further provided with a third ACF protective glue on a side facing the first flexible circuit board, and the third ACF protective glue connects the side of the third ACF pad, the side of the fourth ACF pad and the side of the first flexible circuit board.

[0027] In some possible implementation manners, the display screen bonding area of the first flexible substrate layer away from the ultrasonic fingerprint sensor chip comprises a display screen bonding area corresponding to the chip bonding area, the first ACF pressing area and the second ACF pressing area, and the first connecting layer is arranged on the display screen bonding area.

[0028] In some possible implementation manners, the display screen bonding area covers the chip bonding area, the first ACF pressing area and the second ACF pressing area.

[0029] In some possible implementation manners, the edges of at least part of the laminated layers in the connecting medium layer are beyond the edges of the silicon substrate; and the ultrasonic fingerprint identification device further comprises a fixing glue arranged at the edge area of at least part of the laminated layers in the connecting medium layer, and the fixing glue surrounds and covers at least part of the side of the ultrasonic fingerprint sensor chip.

[0030] In some possible implementation manners, the edges of at least part of the laminated layers in the connecting medium layer are beyond the edges of the silicon substrate by more than 0.5 mm.

[0031] In some possible implementation manners, the edges of at least the first connecting layer in the connecting medium layer are beyond the edges of the silicon substrate.

[0032] In some possible implementation manners, the ultrasonic fingerprint identification device further comprises a light shielding glue arranged on the display screen and surrounding at least part of the laminated layers in the connecting medium layer.

[0033] In some possible implementation manners, the width of the light shielding glue is greater than or equal to 0.1 mm.

[0034] In some possible implementation manners, at least part of the edges of the connecting medium layer are flush with at least part of the edges of the silicon substrate or at least part of the edges of the connecting medium layer are recessed by no more than 0.5 mm compared with at least part of the edges of the silicon substrate, and the ultrasonic fingerprint identification device further comprises a fixing glue arranged on the display screen and surrounding and covering at least part of the side of the connecting medium layer and the ultrasonic fingerprint sensor chip.

[0035] In some possible embodiments, the width of the fixed glue is greater than or equal to 0.1 mm.

[0036] In some possible embodiments, the thickness of the ultrasonic fingerprint identification device is less than or equal to 500 μm.

[0037] 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 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-foldable screen through a connecting medium layer.

[0038] In some possible embodiments, the edge of the buffer layer window is more than 0.1 mm beyond the edge of the connecting medium layer.

[0039] In some possible embodiments, the display screen is a foldable screen, the lowermost layer of the foldable screen is a support layer, and the ultrasonic fingerprint identification device is attached to the support layer through a connecting medium layer.

[0040] In the second aspect, an electronic device is provided, which includes a display screen and an ultrasonic fingerprint identification device as in 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.

[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 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-foldable screen through a connecting medium layer.

[0042] In some possible embodiments, the display screen is a foldable screen, the lowermost layer of the foldable screen is a support layer, and the ultrasonic fingerprint identification device is attached to the support layer. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 FIG. 1 is a schematic structural diagram of an ultrasonic fingerprint identification device provided by an embodiment of the present application.

[0044] Figure 2 FIG. 2 is a schematic structural diagram of an ultrasonic fingerprint sensor chip provided by an embodiment of the present application.

[0045] Figure 3 FIG. 3 is another schematic structural diagram of an ultrasonic fingerprint sensor chip provided by an embodiment of the present application.

[0046] Figure 4 FIG. 4 is a schematic structural diagram of an ultrasonic fingerprint sensor chip 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.

[0047] Figure 5 is another schematic structural diagram of the ultrasonic fingerprint identification device provided by the embodiment of the present application.

[0048] Figure 6 is a schematic structural diagram of two connecting medium layers provided by the embodiment of the present application.

[0049] Figure 7 is another schematic structural diagram of the ultrasonic fingerprint identification device provided by the embodiment of the present application.

[0050] Figure 8 is a schematic structural diagram of the first flexible circuit board provided by the embodiment of the present application.

[0051] Figure 9 is a schematic structural diagram of the ultrasonic fingerprint sensor chip and the second flexible circuit board provided by the embodiment of the present application. Figure 8 is a schematic structural diagram of the connection structure of the first flexible circuit board in the embodiment of the present application.

[0052] Figure 10 is another schematic structural diagram of the ultrasonic fingerprint identification device provided by the embodiment of the present application.

[0053] Figure 11 is another schematic structural diagram of the ultrasonic fingerprint identification device provided by the embodiment of the present application.

[0054] Figure 12 is a schematic structural diagram of the ultrasonic fingerprint identification device provided by the embodiment of the present application. Figure 11 is a schematic top view of the ultrasonic fingerprint identification device in the embodiment shown in FIG. 12.

[0055] Figure 13 is another schematic structural diagram of the ultrasonic fingerprint identification device provided by the embodiment of the present application.

[0056] Figure 14 is a schematic structural diagram of the ultrasonic fingerprint identification device provided by the embodiment of the present application. Figure 13 is a schematic top view of the ultrasonic fingerprint identification device in the embodiment shown in FIG. 13.

[0057] Figure 15 is a schematic structural diagram of the ultrasonic fingerprint identification device under a non-foldable screen provided by the embodiment of the present application.

[0058] Figure 16 is another schematic structural diagram of the ultrasonic fingerprint identification device under a non-foldable screen provided by the embodiment of the present application.

[0059] Figure 17 is a schematic structural diagram of the ultrasonic fingerprint identification device under a foldable screen provided by the embodiment of the present application.

[0060] Figure 18is another schematic structural diagram of the ultrasonic fingerprint identification device under a folding screen, provided by an embodiment of the present application. DETAILED DESCRIPTION

[0061] The technical solution 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 embodiment 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 device, 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 arranged below the display screen that interacts with the user.

[0062] Figure 1 A schematic structural diagram of an ultrasonic fingerprint identification device 10 provided by an embodiment of the present application is shown. The ultrasonic fingerprint identification device 10 can be arranged below the display screen 20 of the electronic device to realize under-screen ultrasonic fingerprint identification.

[0063] As shown in Figure 1 The ultrasonic fingerprint identification device 10 includes an ultrasonic fingerprint sensor chip 100, a first flexible printed circuit (FPC) 200, a second FPC 600, and a connecting medium layer 300.

[0064] Specifically, the ultrasonic fingerprint sensor chip 100 includes a silicon substrate 110 and a piezoelectric transducer 120 arranged on the silicon substrate. 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. 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 identification.

[0065] 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, to prevent external electrical devices from affecting the operation of the ultrasonic fingerprint sensor chip 100 and to ensure the fingerprint identification performance of the ultrasonic fingerprint sensor chip 100.

[0066] The first flexible circuit board 200 is arranged between the ultrasonic fingerprint sensor chip 100 and the display screen 20, and includes a second ACF pad 201 and a third ACF pad 204. The second ACF pad 201 is press-bonded to the first ACF pad 101 of the ultrasonic fingerprint sensor chip 100 to realize electrical connection between the ultrasonic fingerprint sensor chip 100 and the first flexible circuit board 200.

[0067] The second flexible circuit board 600 is arranged below the first flexible circuit board 200 and in parallel with the silicon substrate 110 of the ultrasonic fingerprint sensor chip 100. The second flexible circuit board 600 includes a fourth ACF pad 601. The second flexible circuit board 600 is press-bonded to the third ACF pad 204 of the first flexible circuit board 600 through the fourth ACF pad 601 to realize electrical connection between the first flexible circuit board 200 and the second flexible circuit board 600.

[0068] The connection medium layer 300 is arranged between the piezoelectric transducer 120 of the ultrasonic fingerprint sensor chip 100 and the display screen 20. The connection medium layer 300 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.

[0069] Specifically, in the embodiment of the present application, the ultrasonic fingerprint sensor chip 100 is a special-purpose 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 recognition. 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 is reflected by the finger 21 to form an ultrasonic fingerprint signal 23 carrying fingerprint information. 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 recognition.

[0070] 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 recognition, the circuit unit 111 outputs an excitation signal, such as a sine wave or a pulse wave, to the upper electrode 121 and the lower electrode 123, and controls 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 signal 22 to the finger 21. The ultrasonic fingerprint signal 23 formed by the reflection of the ultrasonic signal 22 on the finger 21 is transmitted to the piezoelectric layer 122, and a potential difference is generated between the upper electrode 121 and the lower electrode 123 based on the inverse piezoelectric effect, thereby obtaining a corresponding fingerprint electric signal. The circuit unit 111 acquires the fingerprint electric signal and processes it to obtain the fingerprint pattern of the finger 21.

[0071] In an implementation, the upper electrode 121 is in a planar structure, and the lower electrode 123 includes an electrode array composed of a plurality of electrodes.

[0072] For example, as shown in Figure 1 , 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 generates an electric signal between the upper electrode 121 and each electrode of the electrode array of the lower electrode 123, and the electric signal corresponding to each electrode can be acquired and processed as a pixel value of a pixel in the fingerprint pattern.

[0073] 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; and the lower electrode 123 can be formed on the lower surface of the piezoelectric layer 122 by sputtering or evaporation, and can be made of aluminum or gold.

[0074] In addition, the surface of the upper electrode 121 and / or the lower electrode 123 can be optionally covered with a passivation layer to electrically isolate the piezoelectric transducer 120 from other medium layers except the circuit unit 111.

[0075] Continuing to refer to Figure 1In 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 first flexible circuit board 200 and a second flexible circuit board 600, and the ultrasonic fingerprint sensor chip 100 can be connected to the external electrical device through the first flexible circuit board 200 and the second flexible circuit board 600. Specifically, the first flexible circuit board 200 and / or the second flexible circuit board 600 can comprise a flexible copper clad laminate (FCCL). Optionally, in the flexible copper clad laminate, the copper foil layer can be arranged on one side or both sides of the flexible substrate layer.

[0076] In the silicon substrate 110 of the ultrasonic fingerprint sensor chip 100, in addition to the circuit unit 111, a first ACF pad 101 is also arranged. Corresponding to the first ACF pad 101, a second ACF pad 101 is arranged in the first flexible circuit board 200, and the first ACF pad 101 and the second ACF pad 201 can be pressed together through an ACF glue layer to realize a stable and reliable electrical connection.

[0077] 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 first flexible circuit board 200 can also be multiple. Through the mutual connection between the multiple first ACF pads 101 and the multiple second ACF pads 201, the mutual transmission of multiple signals between the ultrasonic fingerprint sensor chip 100 and the first flexible circuit board 200 can be realized.

[0078] Further, since the first flexible circuit board 200 is arranged between the ultrasonic fingerprint sensor chip 100 and the display screen 20, in order to prevent the first flexible circuit board 200 from interfering with the display screen 20, a second flexible circuit board 600 can be further arranged below the first flexible circuit board 200, and the ultrasonic fingerprint sensor chip 100 and the first flexible circuit board 200 can output signals to the external electrical device through the second flexible circuit board 600.

[0079] Specifically, the first flexible circuit board 200 and the second flexible circuit board 600 can be arranged with corresponding third ACF pads 204 and fourth ACF pads 601. The third ACF pads 204 and the fourth ACF pads 601 can be pressed and welded with each other through an ACF process, so as to realize a reliable electrical connection between the first flexible circuit board 200 and the second flexible circuit board 600.

[0080] Optionally, the first ACF pad 101, the second ACF pad 201, the third ACF pad 204 and the fourth ACF pad 601 can be referred to as "gold fingers" in some implementations, i.e., the surfaces of the four ACF pads are coated with a gold layer or a nickel-gold layer to meet the requirements of the ACF process and connection reliability.

[0081] By the above technical solution, the ultrasonic fingerprint sensor chip 100 and the first flexible circuit board 200 in the ultrasonic fingerprint identification device 10 can be connected to each other through the ACF pads, and the first flexible circuit board 200 can also be connected to the second flexible circuit board 600 through the ACF pads. The ACF process can be implemented using the ultrasonic fingerprint sensor chip 100 as a support, without the need for an additional support. The ultrasonic fingerprint identification device 10 formed by connecting the ultrasonic fingerprint sensor chip 100, the first flexible circuit board 200 and the second flexible circuit board 600 through the ACF process can have a smaller thickness, facilitating the installation of the ultrasonic fingerprint identification device 10 under the display screen 20 and saving the installation space of the ultrasonic fingerprint identification device 10 under the display screen 20.

[0082] In addition, the arrangement of the first flexible circuit board 200 and the second flexible circuit board 600 not only reduces the risk of interference with the display screen 20, but also saves the thickness installation space required under the display screen 20.

[0083] Continuing to refer to Figure 1 In order to realize the installation of the ultrasonic fingerprint identification device 10 under the display screen 20, the embodiment of the present application 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 signal 22 generated by the piezoelectric transducer 120 and the ultrasonic fingerprint signal 23 returned via the user's finger 21.

[0084] Through 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 under the display screen 20, but also can provide a transmission medium for the ultrasonic signal 22 and the ultrasonic fingerprint signal 23, thereby guaranteeing the fingerprint identification performance of the ultrasonic fingerprint identification device 10.

[0085] 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.

[0086] 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.

[0087] Optionally, in some embodiments, the material of the piezoelectric layer 122 can be polyvinylidene difluoride (PVDF) or polyvinylidene difluoride-trifluoroethylene (PVDF-TrFE), for example.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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, and a redistribution layer (RDL) 113 connected to the chip pad 112 is provided on the surface of the silicon substrate 110, and the first ACF pad 101 is a pad provided on the RDL 113.

[0092] Specifically, multiple layers of metal traces may be provided within the silicon substrate 110 to connect multiple devices within the silicon substrate 110 to form a circuit unit 111. The top layers of the multi-layer metal traces are covered with an insulating layer to protect the metal traces within the silicon substrate 110. The insulating layer on the surface of the top traces is the surface material layer of the silicon substrate 110. Optionally, the insulating layer on the surface of the top traces may have windows formed therein to expose a portion of the top traces to form chip pads 112.

[0093] To facilitate the ACF process on the ultrasonic fingerprint sensor chip 100, in the embodiment of the present application, the first ACF pad 101 can be formed by the RDL 113. Specifically, one end of the RDL 113 is connected to the chip pad 112, and the other end of the RDL 113 is located on the surface of the silicon substrate 110. The first ACF pad 101 can be formed on the RDL 113.

[0094] In some examples, the material of the RDL 113 may be gold, and one end of the RDL 113 located on the surface of the silicon substrate 110 may directly serve as the first ACF pad 101 .

[0095] In other examples, the material of the RDL 113 may be other conductive metal materials, and a gold layer may 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 .

[0096] Optionally, in order to ensure the reliability of the ACF process and thus ensure the reliability of the electrical connection between the first flexible circuit board 200 and the ultrasonic fingerprint sensor chip 100 , the thickness of the RDL 113 may be between 1 μm and 10 μm.

[0097] 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. A top layer trace 114 connected to the chip pad 112 is provided inside the silicon substrate 110. The first ACF pad 101 is a pad provided on the top layer trace 114.

[0098] Specifically, the relevant scheme of the chip pad 112 in the embodiment of the present application can be referred to above. Figure 2The chip pad 112 can be a pad formed on the top layer trace 114, or a partial region of the top layer trace 114 can be used as the chip pad 112.

[0099] Since the silicon substrate 110 has the top layer trace 114 inside, the first ACF pad 101 can be directly formed using the top layer trace 114. Specifically, the insulating layer on the surface of the top layer trace 114 can be windowed to expose a partial region of the top layer trace 114, and a gold layer can be coated on the partial region to form the first ACF pad 101 disposed on the top layer trace 114.

[0100] Specifically, in the embodiment, the top layer trace 114 of the silicon substrate 110 is generally made of aluminum, and the conductive performance of the aluminum cannot meet the requirements of the ACF process. Therefore, the surface of the top layer trace 114 needs to be plated with gold to form the first ACF pad 101 that meets the requirements of the ACF process and ensures the connection reliability between the first flexible circuit board 200 and the ultrasonic fingerprint sensor chip 100.

[0101] Optionally, in some embodiments, as shown in (a) of FIG. 1, Figure 3 the surface of the chip pad 112 can be an air layer, or, as shown in (b) of FIG. 1, Figure 3 the surface of the chip pad 112 can be provided with an insulating layer 103, or, as shown in (c) of FIG. 1, Figure 3 the surface of the chip pad 112 can be coated with a gold layer 104.

[0102] In the embodiments shown in (a) and (c) of FIG. 1, Figure 3 the electrical signal of the chip pad 112 can be detected by a user. Since the chip pad 112 is connected to the first ACF pad 101 and is close to the first ACF pad 101, the electrical signal of the chip pad 112 can be approximately understood as the same as the electrical signal of the first ACF pad 101. Since the first ACF pad 101 is coated with a gold layer, the gold layer structure is relatively fragile and is not convenient for direct detection. Therefore, the electrical signal of the first ACF pad 101 can be detected by detecting the electrical signal of the chip pad 112, so as to facilitate the positioning analysis of the failure of the ultrasonic fingerprint sensor chip 100.

[0103] In the embodiment shown in (b) of FIG. 1, Figure 3 the surface of the chip pad 112 is provided with an insulating layer 103. The insulating layer 103 can avoid the short circuit failure between the first ACF pad 101 and the chip pad 112 during the process of pressing the first ACF pad 101 to the first flexible circuit board 200 by ACF glue, and improve the manufacturing yield of the ultrasonic fingerprint identification device 10.

[0104] Figure 4 Shown Figure 3 FIG. 2( c ) shows a schematic top view of the ultrasonic fingerprint sensor chip 100 .

[0105] 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 a side of a silicon substrate 110, and the plurality of first ACF pads 101 meet at least one of the following conditions: a center distance between two adjacent first ACF pads 101 of the plurality of first ACF pads 101 is between 50 μm and 300 μm; a length of each first ACF pad 101 in the plurality of first ACF pads 101 is greater than or equal to 30 μm; a width of each first ACF pad 101 in the plurality of first ACF pads 101 is greater than or equal to 10 μm; and a distance between an edge of each first ACF pad 101 in the plurality of first ACF pads 101 and an edge of the silicon substrate 110 is greater than or equal to 10 μm.

[0106] Specifically, in this embodiment, the sizes of the plurality of first ACF pads 101 can be designed to be larger, thereby ensuring the reliability of the ACF process and guaranteeing the reliability of the connection between the first flexible circuit board 200 and the ultrasonic fingerprint sensor chip 100. In addition, the center distance between two adjacent first ACF pads 101 in the plurality of first ACF pads 101 is between 50 μm and 300 μm, which can reduce the risk of short circuits between adjacent pads.

[0107] Figure 5 Another schematic structural diagram of the ultrasonic fingerprint recognition device 10 provided in an embodiment of the present application is shown.

[0108] like Figure 5 As shown, in the embodiment of the present application, 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 the dielectric layer 330 has a thickness between 10 μm and 200 μm.

[0109] Specifically, in order to ensure the transmission of ultrasonic waves between the piezoelectric transducer 120 and the display screen 20 and reduce the transmission loss, a dielectric layer 330 may be provided in the connecting dielectric layer 300. The dielectric layer 330 may be a dielectric layer that matches the display screen 20 and the piezoelectric transducer 120. For example, in order to ensure the best transmission performance of the signal when passing through the dielectric layer 330, the acoustic impedance of the layers adjacent to the dielectric layer 330 may be considered. If the acoustic impedances of the adjacent layers on both sides of the dielectric layer 330 are Z1 and Z2 respectively, when the acoustic impedance of the dielectric layer 330 is Z1, the acoustic impedance of the adjacent layers is Z2. At this time, the medium layer 330 and its adjacent layers can achieve the optimal acoustic impedance matching. Wherein, 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 sound speed. For solid materials, the sound speed c is related to its mechanical parameters, satisfying Wherein, Y is the Young's modulus, and v is the Poisson's ratio.

[0110] 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), etc. Alternatively, in some alternative embodiments, the material of the medium layer 330 can also be an inorganic material, such as carbon fiber and glass, etc.

[0111] At the same time, the transmission rate of the ultrasonic wave is also related to the material thickness, for example, through experiments, it can be known that when the thickness d of the medium layer 330 and the wavelength λ of the ultrasonic wave satisfy d = (2n + 1) x (λ / 4), the signal attenuation is large; while 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 to 200 μm, for example, 50 μm.

[0112] In addition, through the setting of the thickness of the medium layer 330, not only is conducive to the transmission of the ultrasonic wave by the medium layer 330, but also can provide a certain gap below the display screen 20 to accommodate the first flexible circuit board 200 connected to the ultrasonic fingerprint sensor chip 100.

[0113] 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 comprises: a first connecting layer 310 and a second connecting layer 320, which can have a glue layer to facilitate the connection of the medium layer 330 between the piezoelectric transducer 120 and the display screen 20.

[0114] Optionally, in some embodiments, as shown in FIG. 3B, the medium layer 330 can be connected to the display screen 20 through the first connecting layer 310 and the second connecting layer 320. Figure 5As shown, in addition to including an upper electrode 121, a piezoelectric layer 122, and a lower electrode 123, the piezoelectric transducer 120 may also include a protective layer 124, which covers 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. In addition, the protective layer 124 is also used to protect the piezoelectric layer 122 to ensure its piezoelectric performance. The provision of the protective layer 124 can prevent the piezoelectric layer 122 and the upper electrode 121 from penetrating and failing under conditions such as high temperature and high humidity, thereby improving the security and reliability of the ultrasonic fingerprint recognition device 10.

[0115] On the basis that the piezoelectric transducer 120 includes 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 .

[0116] Figure 6 Schematic structural diagrams of two connecting medium layers 300 provided in an embodiment of the present application are shown.

[0117] like Figure 6 As shown in (a) and (b) of FIG, the first connection layer 310 may be provided with a first metal layer 311, and the second connection layer 320 may be provided with a second metal layer 321. 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.

[0118] As an example but not a limitation, the material 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.

[0119] Through the technical solution of this embodiment, the two metal layers in the first connection layer 310 and the second connection layer 320 can match the acoustic impedance of the stacked layers in the display screen 20 and the piezoelectric transducer 120, and the two metal layers can generate coherent superposition of ultrasonic waves to further improve the transmission performance of the first connection layer 310 and the second connection layer 320 for ultrasonic waves, thereby improving the fingerprint recognition performance of the ultrasonic fingerprint recognition device 10.

[0120] Based on the above implementation, Figure 6As shown in Figures (a) and (b) of the drawings, the first connection layer 310 may include, in addition to the first metal layer 311, a first adhesive layer 312, which is used to connect the display screen 20 to the first metal layer 311. By way of example and not limitation, the first adhesive layer 312 may be a double-sided adhesive tape, such as a pressure sensitive adhesive (PSA).

[0121] Optionally, the first adhesive layer 312 may be a low-light-transmittance (e.g., black) adhesive layer. The first adhesive layer 312 has an absorptivity greater than 70% for visible light, for example, between 70% and 90%. Specifically, the first adhesive layer 312 is the adhesive layer of the first connecting layer 310 facing the display screen 20. Setting the first adhesive layer 312 as a low-light-transmittance (e.g., black) adhesive layer can reduce or avoid appearance issues caused by placing the ultrasonic fingerprint recognition device 10 below the display screen 20.

[0122] 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 , it is possible to ensure that the first adhesive layer 312 has good and reliable adhesion, thereby improving the installation reliability of the ultrasonic fingerprint recognition device 10 under the display screen 20 .

[0123] Similarly, if Figure 6 As shown in Figures (a) and (b) of the drawings, the second connection layer 320 may include, in addition to the second metal layer 321, a second adhesive layer 322, which is used to connect the piezoelectric transducer 120 and the second metal layer 321. The second adhesive layer 322 may also be a double-sided adhesive tape, and as an example but not a limitation, the second adhesive layer 322 may also be a PSA adhesive layer.

[0124] Optionally, in the second connection layer 320, the thickness of the second adhesive layer 322 may 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 and other issues, the ultrasonic fingerprint sensor chip 100 may be warped, affecting the overall performance and required thickness space of the ultrasonic fingerprint recognition device 10. In view of this, 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 bonding effect of the second adhesive layer 322, thereby improving the overall performance of the ultrasonic fingerprint recognition device 10 and reducing the thickness space required for the ultrasonic fingerprint recognition device 10 under the display screen 20.

[0125] 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 FIG. (b) of Figure 6 The third adhesive layer 313 can be further disposed in the first connecting layer 310, and the fourth adhesive layer 323 can be further disposed in the second connecting layer 320, respectively. The third adhesive layer 313 is used to connect the first metal layer 311 to the dielectric layer 330, and the fourth adhesive layer 323 is used to connect the second metal layer 321 to the dielectric layer 330.

[0126] 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 to facilitate the connection between the metal layer and other layers.

[0127] 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, thereby ensuring 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 occupied by 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.

[0128] Alternatively, in other embodiments, as shown in FIG. (b) of Figure 6As 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 the 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.

[0129] Figure 7 Another schematic structural diagram of the ultrasonic fingerprint identification device 10 provided by the embodiment of the present application is shown.

[0130] As shown in Figure 7 In the embodiment of the present application, the first 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 first flexible circuit board 200 can be reused as the connecting medium layer 300.

[0131] Specifically, the first flexible circuit board 200 can be arranged above the ultrasonic fingerprint sensor chip 100 and can be used to connect the piezoelectric transducer 120 of the ultrasonic fingerprint sensor chip 100 and the display screen 20. While the first flexible circuit board 200 is used to connect the display screen 20 and the ultrasonic fingerprint sensor chip 100, the side of the first flexible circuit board 200 facing the ultrasonic fingerprint sensor chip 100 is provided with the second ACF pad 201 and the third ACF pad 204, 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 third ACF pad 204 is arranged opposite to the fourth ACF pad 601 on the second flexible circuit board 600, and the two groups of ACF pads can be connected to each other through the ACF adhesive layer 202.

[0132] By the technical solutions of the embodiments of the present application, while the first flexible circuit board 200 is used to electrically connect the ultrasonic fingerprint sensor chip 100 and the second flexible circuit board 600 to transmit the signal of the ultrasonic fingerprint sensor chip 100, the first 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.

[0133] Specifically, in some embodiments, the first flexible substrate layer in the first flexible circuit board 200 can be reused as the medium layer 330 in the connection medium layer 300, and the metal layer in the first 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.

[0134] It can be understood that the first 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 first flexible substrate layer in the first flexible circuit board 200 is generally an organic polymer material, such as PET, PI, etc., and the metal layer in the first flexible circuit board 200 can be a copper foil layer covering the surface of the flexible substrate layer. Therefore, the first flexible substrate layer in the first 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.

[0135] By the technical solutions of the embodiments, the first 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.

[0136] In order to facilitate the description of the related structure of the first flexible circuit board 200 provided by the embodiments of the present application, Figure 8 A schematic structural diagram of a first flexible circuit board 200 is separately shown.

[0137] In the first flexible circuit board 200, the side of the first flexible substrate layer 210 (the lower surface of the first flexible substrate layer 210 shown in the figure) facing the ultrasonic fingerprint sensor chip 100 comprises a chip bonding area 231 and a first 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 first 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.

[0138] Specifically, in this embodiment, the first flexible substrate layer 210 can completely cover the ultrasonic fingerprint sensor chip 100. On the side of the first 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 first 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 first ACF compression area 232 are two independent areas and do not overlap each other.

[0139] The part of the first 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.

[0140] Optionally, in this embodiment, the first flexible substrate layer 210 is provided with a first adhesive layer 211 between the first flexible substrate layer 210 and the first copper foil layer 221, and the first adhesive layer 211 can be reused as the third adhesive layer 323 in the second connection layer 320. Figure 8 In the embodiment shown, no adhesive layer is arranged between the first flexible substrate layer 210 and the first copper foil layer 221, or an adhesive layer can also be arranged between the first flexible substrate layer 210 and the first copper foil layer 221, and the adhesive layer can be reused as the fourth adhesive layer 323 in the second connection layer 320.

[0141] In addition to the first copper foil layer 221 described above, the side of the first 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 first ACF compression area 232, and the first ACF compression area 232 is also provided with a second ACF pad 201 electrically connected to the second copper foil layer 222.

[0142] Specifically, the second copper foil layer 222 can be disconnected with the first copper foil layer 221, i.e. the first copper foil layer 221 is not connected with 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 ultrasonic wave transmission. The first copper foil layer 221 only serves as a medium layer to transmit 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 device 10.

[0143] Optionally, in the embodiment shown in Figure 8 In the embodiment shown, a first copper deposition layer 251 is further formed between the second copper foil layer 222 and the second ACF pad 201, and the first copper deposition layer 251 can be connected to the second copper foil layer 222 to form a circuit trace layer in the first flexible circuit board 200. The second ACF pad 201 can be connected to the second copper foil layer 222 through the first copper deposition layer 251, thereby forming an input and output interface for electrical signals in the first flexible circuit board 200.

[0144] Through the technical solutions of the embodiments of the present application, in the first flexible circuit board 200, one side of the first flexible substrate layer 210 facing the ultrasonic fingerprint sensor chip 100 includes two mutually independent chip bonding areas 231 and a first ACF compression area 232. The chip bonding area 231 is used to dispose the first copper foil layer 221 and is 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 first ACF compression area 232 is used to dispose the second copper foil layer 222 and the second ACF pad 201 and is 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 device 10 in which it is located can be comprehensively ensured.

[0145] Optionally, in the embodiment shown in Figure 8 In the embodiment shown, in order to facilitate the attachment of the first flexible circuit board 200 to the display screen 20, the upper surface of the first flexible substrate layer 210 can not be provided with a copper foil layer. When it is necessary to attach the first flexible circuit board 200 to the display screen 20, a connecting layer can be provided on the upper surface of the first flexible substrate layer 210, thereby connecting the first flexible circuit board 200 and the display screen 20. The structure of the connecting layer can be the same as that of the first connecting layer 310 in the above embodiment.

[0146] Alternatively, in other embodiments, a copper foil layer may be provided on the upper surface of the first flexible substrate layer 210. This copper foil layer may reuse the first metal layer 311 of the connecting dielectric layer 300. When the first flexible circuit board 200 is to be attached to the display screen 20, an adhesive layer may be provided on the surface of the copper foil layer to connect the first flexible circuit board 200 to the display screen 20. This adhesive layer may have the same structure as the first adhesive layer 312 in the above embodiment.

[0147] Figure 9 The embodiment of the present application provides an ultrasonic fingerprint sensor chip 100 and a second flexible circuit board 600 and Figure 8 Schematic diagram of the connection structure of the first flexible circuit board 200.

[0148] like Figure 9 As shown, the side of the silicon substrate 110 in the ultrasonic fingerprint sensor chip 100 facing the first flexible circuit board 200 (the upper surface of the silicon substrate 110 shown in the figure) includes: an effective identification area 115, 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.

[0149] Specifically, the ultrasonic fingerprint sensor chip 100 is a silicon substrate 110, which may be provided with a pixel circuit connected to the lower electrode 123 in the piezoelectric transducer 120. Specifically, the lower electrode 123 is a lower electrode array formed by multiple electrodes, and a pixel circuit array is formed in the silicon substrate 110, and each circuit in the pixel circuit array is connected to an 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 embodiment of the present application. The circuit unit 111 in the above embodiment may include the pixel circuit array in the embodiment of the present application and other auxiliary circuits. The area where the auxiliary circuit is located can be referred to as the non-effective identification area.

[0150] It is understood that the piezoelectric transducer 120 needs to be disposed 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 cover the effective identification area 115.

[0151] If the chip bonding area 231 of the first 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 first flexible circuit board 200, due to the influence of mounting process and manufacturing process, etc., the first flexible circuit board 200 can not completely cover the effective recognition area 115, thereby affecting the transmission of the ultrasonic signal of the ultrasonic fingerprint sensor chip 100 by the first flexible circuit board 200.

[0152] Therefore, in the embodiment of the present application, the edge of the chip bonding area 231 of the first 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 first 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 first flexible circuit board 200.

[0153] 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 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.

[0154] Further, in order to more effectively guarantee the transmission of the ultrasonic signal by the first 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.

[0155] Continuing to refer to Figure 9 , in the embodiment of the present application, the side of the first flexible circuit board 200 facing the silicon substrate 110 is also provided with a first ACF protective glue 203, which connects the side of the second ACF pad 201 and the side of the silicon substrate 110.

[0156] Optionally, when the side of the second copper foil layer 222 facing 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.

[0157] Specifically, after the second ACF pad 201 is connected to the first ACF pad 101 of the silicon substrate 110 via the ACF adhesive layer 202, to protect the ACF bonding area, adhesive can be dispensed on the side of the silicon substrate 110 adjacent to the first ACF pad 101 to form a first ACF protective adhesive 203. This first ACF protective adhesive 203 can cover at least a portion of the side surface of the silicon substrate 110, the second ACF pad 201, and the side surface of the ACF adhesive layer 202, thereby effectively protecting the ACF bonding area. Furthermore, the solidified first ACF protective adhesive 203 can also provide support for the edge of the first flexible circuit board 200 located on the silicon substrate 110, thereby improving the stability of the first flexible circuit board 200 beneath the display screen 20.

[0158] Combined with the above Figure 8 and Figure 9 The connection between the first flexible circuit board 200 and the ultrasonic fingerprint sensor chip 100 is described below. Figure 8 and Figure 9 The connection between the first flexible printed circuit board 200 and the second flexible printed circuit board 600 will be described below.

[0159] Continue to see Figure 8 As shown, in the first flexible circuit board 200, in addition to the above-mentioned chip bonding area 231 and the first ACF pressing area 232, the side of the first flexible substrate layer 210 facing the ultrasonic fingerprint sensor chip 100 also includes: a second ACF pressing area 233, which is located on the side of the first ACF pressing area 232 away from the chip bonding area 231, and the second ACF pressing area 233 is provided with a second copper foil layer 222 and a third ACF pad 204 electrically connected to the second copper foil layer 222.

[0160] Specifically, in this embodiment, the second copper foil layer 222 of the first flexible circuit board 200 can extend to cover the first ACF pressing area 232 and the second ACF pressing area 233. The first ACF pad 201 and the third ACF pad 204 on the second copper foil layer 222 can be two independent pads, or the first ACF pad 201 and the third ACF pad 204 can be combined into a single pad.

[0161] Continue to see Figure 9 As shown, in the second flexible circuit board 600 provided in the embodiment of the present application, the side of its second flexible substrate layer 610 facing the display screen 20 includes: a third ACF pressing area 234 corresponding to the above-mentioned second ACF pressing area 233, and the third ACF pressing area 234 is provided with a third copper foil layer 621 and a fourth ACF pad 601 electrically connected to the third copper foil layer 621.

[0162] Optionally, in order to guarantee the connection reliability between the first flexible circuit board 200 and the second flexible circuit board 600, in the first flexible circuit board 200, the second copper foil layer 222 further has a second ACF protective glue 205 provided on the side thereof facing the second flexible circuit board 600, the second ACF protective glue 205 connecting the side of the third ACF pad 204, the side of the fourth ACF pad 601 and the side of the second flexible circuit board 600.

[0163] Specifically, the second ACF protective glue 205 can be dispensed on the lower surface of the first flexible circuit board 200, and the third ACF pad 204 and the fourth ACF pad 601 can be connected to the second ACF protective glue 205. Figure 9 In the illustrated embodiment, the lower surface of the first flexible circuit board 200 can be the first copper plating layer 251, and the lower surface of the first copper plating layer 251 can be provided with the second ACF protective glue 205, which not only can be used to connect the sides of the third ACF pad 204 and the fourth ACF pad 601 facing the silicon substrate 110 to protect the third ACF pad 204 and the fourth ACF pad 601, but also can be used to connect the sides of other layers of the second flexible circuit board 600 to further enhance the connection reliability between the first flexible circuit board 200 and the second flexible circuit board 600.

[0164] Similarly to the second ACF protective glue 205 described above, in the second flexible circuit board 600, the third copper foil layer 621 further has a third ACF protective glue 206 provided on the side thereof facing the first flexible circuit board 200, the third ACF protective glue 206 connecting the side of the third ACF pad 204, the side of the fourth ACF pad 601 and the side of the first flexible circuit board 200.

[0165] Specifically, the third ACF protective glue 206 can be dispensed on the upper surface of the second flexible circuit board 600, and the third ACF pad 204 and the fourth ACF pad 601 can be connected to the third ACF protective glue 206. Figure 9 In the illustrated embodiment, the upper surface of the first flexible circuit board 200 can be a copper plating layer covering the third copper foil layer 621, and the upper surface of the copper plating layer can be provided with the third ACF protective glue 206, which not only can be used to connect the sides of the third ACF pad 204 and the fourth ACF pad 601 away from the silicon substrate 110 to protect the third ACF pad 204 and the fourth ACF pad 601, but also can be used to connect the sides of other layers of the first flexible circuit board 200 to further enhance the connection reliability between the first flexible circuit board 200 and the second flexible circuit board 600.

[0166] Optionally, in some embodiments, the second flexible circuit board 600 can have the same laminated structure as the flexible circuit board in the related art. The second flexible circuit board 600 can be a single-sided flexible circuit board or a double-sided flexible circuit board.

[0167] Figure 10 Another schematic structural diagram of the ultrasonic fingerprint identification device 10 is shown.

[0168] As shown in Figure 10 In the first flexible circuit board 200, the side of the first 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, the first ACF compression area 232, and the second ACF compression area 233. The first connecting layer 310 in the connecting medium layer 300 is arranged in the display screen bonding area 235.

[0169] Specifically, in the embodiment of the present application, when the first 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, the first ACF compression area 232, and the second ACF compression area 233, that is, in the direction perpendicular to the display screen 20, the display screen bonding area 235 at least partially overlaps the chip bonding area 231, the display screen bonding area 235 at least partially overlaps the first ACF compression area 232, and the display screen bonding area 235 at least partially overlaps the second ACF compression area 233.

[0170] By arranging the first connecting layer 310 in the display screen bonding area 235 corresponding to the chip bonding area 231, the first ACF compression area 232, and the second ACF compression area 233 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.

[0171] In some possible embodiments, the display screen bonding area 235 can cover the chip bonding area 231, the first ACF compression area 232, and the second ACF compression area 233. Specifically, the chip bonding area 231, the first ACF compression area 232, and the second ACF compression area 233 can be completely located in the projection of the display screen bonding area 235 in the direction perpendicular to the display screen 20. Through 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.

[0172] Figure 11Another schematic structural diagram of the ultrasonic fingerprint recognition device 10 provided in the embodiment of the present application is shown. Figure 11 In the embodiment shown, the related technical solutions of the first flexible circuit board 200 and the second flexible circuit board 600 can be found in the above Figure 7 to Figure 10 The technical solutions of the illustrated embodiments will not be described in detail here.

[0173] like Figure 11 As shown, in the embodiment of the present application, the edge of at least a portion of the laminated layers in the connecting dielectric layer 300 extends beyond the edge of the silicon substrate 110. The ultrasonic fingerprint recognition device 10 further includes: a fixing glue 400, which is disposed in the edge region of at least a portion of the laminated layers in the connecting dielectric layer 300. The fixing glue 400 surrounds the ultrasonic fingerprint sensor chip 100 and covers at least a portion of the side surface of the ultrasonic fingerprint sensor chip 100.

[0174] As an example, in Figure 11 In the illustrated embodiment, the first connection layer 310 in the connecting dielectric layer 300 extends beyond the edge of the silicon substrate 110 in a direction parallel to the display screen 20. A fixing adhesive 400 is disposed on the lower surface of the first connection layer 310 and surrounds the edge region of the first connection layer 310. Simultaneously, the fixing adhesive 400 also surrounds at least a portion of the side surfaces of the ultrasonic fingerprint sensor chip 100, specifically, the fixing adhesive 400 surrounds at least a portion of the side surfaces of the silicon substrate 110 of the ultrasonic fingerprint sensor chip 100 and at least a portion of the side surfaces of the piezoelectric transducer 120, thereby securing the ultrasonic fingerprint sensor chip 100 to the first connection layer 310. The side surfaces of the ultrasonic fingerprint sensor chip 100 are perpendicular to the display screen 20.

[0175] In the technical solution of the embodiment of the present application, the provision of the fixing adhesive 400 can improve the connection reliability between the ultrasonic fingerprint sensor chip 100 and at least a portion of the laminated layer of the connecting dielectric layer 300, thereby further improving the connection reliability of the ultrasonic fingerprint recognition device 10 below the display screen 20. In addition, because the fixing adhesive 400 is provided in at least a portion of the laminated layer of the connecting dielectric layer 300, it does not directly contact the display screen 20. Therefore, when the ultrasonic fingerprint recognition device 10 is reworked and disassembled, handling the fixing adhesive 400 will not affect the display screen 20. Therefore, the technical solution of this embodiment can facilitate the rework of the ultrasonic fingerprint recognition device 10 below the display screen 20.

[0176] Optionally, the fixing glue 400 can be an ultraviolet light curing glue (which can be referred to as UV curing glue for short), and the fixing glue 400 can be cured by ultraviolet light curing or ultraviolet light and moisture curing. Alternatively, the fixing glue 400 can also be a low-temperature (less than or equal to 100°C) curing glue layer, which can also be called a heat-curing glue. The UV curing glue or heat-curing glue can be, for example, an epoxy resin material. By curing the fixing glue 400 by the above-mentioned curing methods, the influence of high-temperature curing on the display screen 20 and the ultrasonic fingerprint recognition device 10 can be avoided. In addition, the curing shrinkage rate of the fixing glue 400 can be or equal to 3% to ensure the fixing effect of the fixing glue 400 on the ultrasonic fingerprint recognition device 10.

[0177] Optionally, in some embodiments, the edge of at least part of the stack of connecting dielectric layers 300 extends beyond the edge of the silicon substrate 110 by more than 0.5 mm, for example, Figure 11 In the illustrated embodiment, 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.

[0178] The technical solution of this embodiment effectively ensures that the fixing adhesive 400 effectively connects the connecting dielectric layer 300 and the silicon substrate 110, even if there are manufacturing or installation tolerances in the connecting dielectric layer 300 and / or the silicon substrate 110, thereby ensuring the reliable installation of the ultrasonic fingerprint recognition device 10 beneath the display screen 20. Furthermore, at least a portion of the laminated layers in the connecting dielectric layer 300 can completely cover the silicon substrate 110, thereby preventing the ultrasonic fingerprint sensor chip 100, where the silicon substrate 110 is located, from being visible to the user through the display screen 20, thereby improving the appearance of the display screen 20.

[0179] Optionally, in addition to the above Figure 11 In addition to the technical solution in which the edge of the first connection layer 310 in the connection dielectric layer 300 extends beyond the edge of the silicon substrate 110 in the illustrated embodiment, in other alternative embodiments, the edges of multiple layers in the connection dielectric layer 300 may extend beyond the edge of the silicon substrate 110. For example, the first connection layer 310 and the dielectric layer 330 may extend beyond the edge of the silicon substrate 110, or all the layers in the connection dielectric layer 300 may extend beyond the edge of the silicon substrate 110.

[0180] In some cases, when the ultrasonic fingerprint recognition device 10 is disposed below the light-transmitting layer in the display screen 20 , in order to further improve the appearance problem caused by the ultrasonic fingerprint sensor chip 100 being disposed below the display screen 20 , the ultrasonic fingerprint recognition device 10 may further include a light-shielding glue 500 .

[0181] Continue to see Figure 11As shown, in the embodiment of the present application, the ultrasonic fingerprint identification device 10 can further include a light shielding glue 500, which is arranged on the display screen 20 and surrounds at least part of the layers in the connecting medium layer 300. For example, the light shielding glue 500 can surround the first connecting layer 310.

[0182] Specifically, the light shielding glue 500 can be a black glue layer to play a better light shielding effect. Further, the light shielding glue 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 shielding glue 500 can further well 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 under the transparent layer of the display screen 20.

[0183] Optionally, in order to ensure the light shielding effect of the light shielding glue 500, the width of the light shielding glue 500 can be greater than or equal to 0.1 mm, and / or the light shielding glue 500 has an absorption rate of visible light greater than or equal to 70%, for example, the absorption rate of visible light of the light shielding glue 500 is between 70% and 90%.

[0184] Optionally, the light shielding glue can be a pressure sensitive adhesive (PSA), a UV curing glue, a heat curing glue, a UV curing glue, or a thermoplastic ink, etc. Among them, the heat curing glue and the UV curing glue can be, for example, an epoxy material.

[0185] Figure 12 As shown Figure 11 A schematic top view of the ultrasonic fingerprint identification device 10 in the embodiment.

[0186] As Figure 12 As shown, the silicon substrate 110 can be a rectangular substrate, and the first connecting layer 310 can also be rectangular. The area of the first connecting layer 310 can be greater than the area of the silicon substrate 110, and the first connecting layer 310 can cover the silicon substrate 110. The length direction of the first connecting layer 310 is the same as the length direction of the silicon substrate 110, and the width direction of the first connecting layer 310 is the same as the width direction of the silicon substrate 110.

[0187] In the length direction L of the silicon substrate 110 and the first connecting layer 310, the distance D1 between the first connecting layer 310 and the silicon substrate 110 is greater than or equal to 0.5 mm. Similarly, in the width direction W of the silicon substrate 110 and the first connecting layer 310, the distance D2 between the first connecting layer 310 and the silicon substrate 110 is greater than or equal to 0.5 mm.

[0188] Furthermore, given that both the silicon substrate 110 and the first connection 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 first connection layer 310, and the width D3 of the light-shielding adhesive 500 is greater than or equal to 0.1 mm. The fixing adhesive 400 is disposed around the silicon substrate 110 and can include a notch to allow for the first flexible printed circuit board 200 electrically connected to the silicon substrate 110 and the second flexible printed circuit board 600 electrically connected to the first flexible printed circuit board 200.

[0189] Figure 13 Another schematic structural diagram of the ultrasonic fingerprint recognition device 10 provided in the embodiment of the present application is shown. Figure 13 In the embodiment shown, the related technical solutions of the first flexible circuit board 200 and the second flexible circuit board 600 can be found in the above Figure 7 to Figure 10 The technical solutions of the illustrated embodiments will not be described in detail here.

[0190] like Figure 13 As shown, in the embodiment of the present application, at least a portion of the edge of the connecting dielectric layer 300 is flush with at least a portion of the edge of the silicon substrate 110, or at least a portion of the edge of the connecting dielectric layer 300 is retracted within 0.5 mm compared to at least a portion of the edge of the silicon substrate 110. The ultrasonic fingerprint recognition device 10 further includes: a fixing glue 400, which is disposed on the display screen 20. The fixing glue 400 surrounds the connecting dielectric layer 300 and the ultrasonic fingerprint sensor chip 100 and covers at least a portion of the side surfaces of the connecting dielectric layer 300 and the ultrasonic fingerprint sensor chip 100.

[0191] As an example, in Figure 13 In the illustrated embodiment, the fixing adhesive 400 is disposed on the lower surface of the display screen 20 and surrounds the side surfaces of the connecting dielectric layer 300. Simultaneously, the fixing adhesive 400 also surrounds the side surfaces of the ultrasonic fingerprint sensor chip 100. In a direction perpendicular to the display screen 20, the fixing adhesive 400 can cover the side surfaces of the connecting dielectric layer 300 and at least a portion of the side surfaces of the ultrasonic fingerprint sensor chip 100, thereby securing the ultrasonic fingerprint sensor chip 100 to the connecting dielectric layer 300 and the display screen 20.

[0192] The provision of the fixing adhesive 400 improves the connection reliability between the ultrasonic fingerprint sensor chip 100, the connecting dielectric layer 300, and the display screen 20, thereby further improving the connection reliability of the ultrasonic fingerprint recognition device 10 below the display screen 20. Furthermore, the fixing adhesive 400 is directly provided on the lower surface of the display screen 20. In some cases, the fixing adhesive 400 can also serve as a light-shielding adhesive to improve the appearance of the ultrasonic fingerprint recognition device 10 below the display screen 20.

[0193] Optionally, in order to ensure the light-shielding effect of the fixing glue 400 as a light-shielding glue, the width of the fixing glue 400 may be greater than or equal to 0.1 mm.

[0194] Figure 14 Shown Figure 13 A schematic top view of the ultrasonic fingerprint recognition device 10 in the illustrated embodiment.

[0195] With the above Figure 12 Similar, such as Figure 14 As shown, the silicon substrate 110 may be a rectangular substrate, and the fixing glue 400 disposed around the silicon substrate 110 may be frame-shaped. In the length direction L and width direction W of the silicon substrate 110, the width D3 of the fixing glue 400 may be greater than or equal to 0.1 mm.

[0196] In addition, Figure 14 In the illustrated embodiment, a side of the silicon substrate 110 provided with the first ACF pad 101 may correspond to the connection end of the first flexible circuit board 200 and the second flexible circuit board 600. A notch may be provided in the fixing adhesive 400 to avoid the area where the connection end of the first flexible circuit board 200 and the second flexible circuit board 600 is located. That is, the fixing adhesive 400 may be provided around the silicon substrate 110 except for the area where the connection end of the first flexible circuit board 200 and the second flexible circuit board 600 is located.

[0197] Through the technical solutions of the above-mentioned application embodiments, by controlling the thickness and connection method of each layer in the ultrasonic fingerprint recognition device 10, the overall thickness range of the ultrasonic fingerprint recognition device 10 can be made less than or equal to 500 μm, thereby reducing the installation thickness space required for the ultrasonic fingerprint recognition device 10 under the display screen 20.

[0198] In some embodiments, the ultrasonic fingerprint recognition device 10 can be disposed below a non-folding screen, that is, the display screen 20 is a non-folding screen.

[0199] Figure 15 A schematic structural diagram of the ultrasonic fingerprint recognition device 10 provided in an embodiment of the present application under a non-folding screen is shown.

[0200] like Figure 15 As shown, the bottom layer of the non-folding screen is a buffer layer 24, in which a buffer layer window 240 is formed. The ultrasonic fingerprint recognition device 10 is arranged in the buffer layer window 240 and is adhered to the substrate layer 25 above the buffer layer 24 in the non-folding screen through a connecting medium layer 300.

[0201] Optionally, the substrate layer 25 may be an organic material layer, for example, PI, and the other circuit layers and the light-emitting layer of the display screen 20 are all fabricated on the substrate layer 25. A buffer layer 24 is provided below the substrate layer 25. The buffer layer 24 may include a foam layer and a copper foil layer, etc., and is used to provide buffering, light shielding, and heat dissipation for the display screen 20.

[0202] In order to reduce the installation space of the ultrasonic fingerprint recognition device 10 under the non-folding screen, and to reduce the influence of the relevant 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 arranged in the buffer layer window 240 and is connected to the substrate layer 25 through the connecting medium layer 300, thereby being installed under the display screen 20.

[0203] like Figure 15 As shown, in this embodiment, the ultrasonic fingerprint recognition device 10 may include a fixing glue 400 and a light shielding glue 500, wherein the fixing glue 400 is provided on the connecting medium layer 300 for fixing the ultrasonic fingerprint sensor chip 100 and the connecting medium layer 300, and the light shielding glue 500 is provided on the display screen 20 for surrounding the connecting medium layer 300 and providing light shielding. Specifically, the relevant technical solutions of the ultrasonic fingerprint recognition device 10 can be found above. Figure 11 and Figure 12 The description of the embodiments shown will not be repeated here.

[0204] In an embodiment of the present application, in order to prevent the optical signals of structures such as the ultrasonic fingerprint sensor chip 100 and the first flexible circuit board 200 from being observed by the user through the buffer layer window 240, the light-shielding glue 500 can be set in the buffer layer window 240 and located in the edge area of ​​the buffer layer window 240. The light-shielding glue 500 and the connecting medium layer 300 as a whole can completely fill the buffer layer window 240, so as to improve and solve the appearance problem of the ultrasonic fingerprint recognition device 10 under the non-folding screen.

[0205] Figure 16 A schematic structural diagram of the ultrasonic fingerprint recognition device 10 provided in an embodiment of the present application under a non-folding screen is shown.

[0206] like Figure 16 As shown, in this embodiment, the ultrasonic fingerprint recognition device 10 may include a fixing glue 400, wherein the fixing glue 400 is provided on the display screen 20, and is used to fix the ultrasonic fingerprint sensor chip 100 and the connecting medium layer 300 to the display screen 20, and the fixing glue 400 is provided around the connecting medium layer 300 to play a light shielding role. Specifically, the relevant technical solutions of the ultrasonic fingerprint recognition device 10 can be referred to above. Figure 13 andFigure 14 The related description of the embodiments is not described in detail here.

[0207] In the embodiments of the present application, in order to prevent the light signal of the ultrasonic fingerprint sensor chip 100 and the first flexible circuit board 200 and the like structure from being observed by the user through the buffer layer window 240, the fixing glue 400 can be arranged in the buffer layer window 240 and located at the edge area of the buffer layer window 240. The fixing glue 400 and the whole connecting medium layer 300 can completely fill the buffer layer window 240, so as to improve the appearance problem of the ultrasonic fingerprint identification device 10 under the non-folded screen.

[0208] Optionally, in the above Figure 15 and Figure 16 embodiments, the edge of the buffer layer window 240 can exceed the edge of the connecting medium layer 300 by more than 0.1 mm.

[0209] Specifically, in the case where the connecting medium layer 300 is rectangular, the buffer layer window 240 can also be a rectangular window adapted to the rectangular 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 more than 0.1 mm, so as to facilitate the installation of the connecting medium layer 300 in the buffer layer window 240, and further facilitate the installation of the ultrasonic fingerprint identification device 10 in the buffer layer window 240 through the connecting medium layer 300.

[0210] Since there is a gap of more than 0.1 mm 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 the above Figure 15 or the fixing glue 400 shown in the above Figure 16 , so as to play a good light shielding role.

[0211] In other embodiments, the ultrasonic fingerprint identification device 10 can also be arranged under the folded screen, that is, the above-mentioned display screen 20 is a folded screen.

[0212] Figure 17 and Figure 18 Two schematic structural diagrams of the ultrasonic fingerprint identification device 10 provided by the embodiments of the present application under the folded screen are shown.

[0213] As shown in Figure 17 and Figure 18 , the lowermost layer of the folded 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 support material with high strength.

[0214] Specifically, due to the special requirement of folding, the bottom layer of the folding screen needs to be provided with a support layer 26, and the support layer 26 cannot be windowed, so as 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 embodiment of the present application can be directly connected to the bottom layer of the folding screen, that is, connected to the support layer 26 through the connecting medium layer 300.

[0215] Since the bottom layer of the folding screen is provided with a support layer 26, the ultrasonic fingerprint identification device 10 arranged below the display screen 20 does not need to consider the appearance problem. As shown in Figure 17 , 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 the embodiment can refer to the description of the other parts except the light shielding glue 500 in the above Figure 11 and Figure 12 , which will not be described in detail here.

[0216] As shown in Figure 18 , the ultrasonic fingerprint identification device 10 can also be directly fixed and connected to the support layer 26 through the fixing glue 400. The specific scheme of the ultrasonic fingerprint identification device 10 in the embodiment can refer to the related description in the above Figure 13 and Figure 14 , which will not be described in detail here.

[0217] The embodiment of the present application also provides an electronic device, which includes a display screen 20 and the ultrasonic fingerprint identification device 10 in any of the above embodiments. Wherein, the display screen is used to provide a pressing interface of a user's finger and receive the pressing of the user's finger. The ultrasonic fingerprint identification device 10 is arranged below the display screen 20 and used to identify the fingerprint of the user's finger pressed on the display screen 20.

[0218] Optionally, the electronic device includes but is not limited to a mobile terminal device, such as a mobile phone, a notebook computer, a tablet computer, etc.

[0219] Optionally, the electronic device can also include a battery, which is also arranged below the display screen 20. In the embodiment of the present application, since the thickness of the ultrasonic fingerprint identification device 10 is relatively thin, the ultrasonic fingerprint identification device 10 can be arranged between the battery and the display screen 20. Through the technical scheme of the embodiment, the installation space required by the ultrasonic fingerprint identification device 10 in the electronic device can be saved.

[0220] In some embodiments, the display screen 20 described above can be a non-foldable screen, the lowermost layer of which is a buffer layer, a buffer layer window is formed in the buffer layer, and the ultrasonic fingerprint identification device 10 is arranged in the buffer layer window and adheres to the substrate layer above the buffer layer in the non-foldable screen.

[0221] Specifically, the related technologies of the non-foldable screen and the ultrasonic fingerprint identification device 10 in this embodiment can refer to the technical solutions of the embodiments shown in the above Figure 15 and Figure 16 , and will not be described in detail here.

[0222] In other embodiments, the display screen 20 described above can be a foldable screen, the lowermost layer of which is a support layer, and the ultrasonic fingerprint identification device 10 adheres to the support layer.

[0223] Specifically, the related technologies of the foldable screen and the ultrasonic fingerprint identification device 10 in this embodiment can refer to the technical solutions of the embodiments shown in the above Figure 17 and Figure 18 , and will not be described in detail here.

[0224] It should be understood that the specific examples in the embodiments of the present application are only to help those skilled in the art better understand the embodiments of the present application, and not to limit the scope of the embodiments of the present application.

[0225] For example, various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, various possible combination manners will not be described again in the present application.

[0226] 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.

[0227] 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.

[0228] Those skilled in the art can understand that the units of the examples described in combination 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.

[0229] In several embodiments provided in 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. For example, the division of the modules is only a logical function division. In actual implementation, another division mode can be used. 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 can be indirect coupling or communication connection through some interfaces, devices or modules, and can also be electrical, mechanical or other forms of connection.

[0230] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within 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 identification device, characterized by comprising: It is installed under the display screen of an electronic device to realize under-screen ultrasonic fingerprint recognition. The ultrasonic fingerprint recognition device 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 an ultrasonic signal to a finger pressing on the display screen and receive an ultrasonic fingerprint signal 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 to the upper electrode and the lower electrode to control the piezoelectric transducer to generate the ultrasonic signal and detect the ultrasonic fingerprint signal for fingerprint recognition. a first flexible circuit board, disposed between the ultrasonic fingerprint sensor chip and the display screen, the first flexible circuit board comprising: a second ACF pad and a third ACF pad, the first flexible circuit board being press-connected to the first ACF pad of the ultrasonic fingerprint sensor chip through the second ACF pad to achieve electrical connection between the ultrasonic fingerprint sensor chip and the first flexible circuit board; a second flexible circuit board, disposed below the first flexible circuit board and arranged side by side with the silicon substrate of the ultrasonic fingerprint sensor chip, the second flexible circuit board comprising: a fourth ACF pad, the second flexible circuit board being press-connected to the third ACF pad of the first flexible circuit board via the fourth ACF pad to achieve electrical connection between the first flexible circuit board and the second 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 transmit the ultrasonic fingerprint signal to the piezoelectric transducer. 2.The ultrasonic fingerprint identification 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 identification device according to claim 1, characterized in that, The material of the piezoelectric layer is polyvinylidene fluoride (PVDF) or polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE). The thickness of the piezoelectric layer is between 4 μm and 40 μm. 4.The ultrasonic fingerprint identification device of claim 1, wherein, The circuit unit includes a chip pad, a redistribution layer (RDL) connected to the chip pad is provided on the surface of the silicon substrate, and the first ACF pad is a pad provided on the RDL.

5. The ultrasonic fingerprint identification device of claim 4, wherein, The thickness of the RDL is between 1 μm and 10 μm. 6.The ultrasonic fingerprint identification device of claim 1, wherein, The circuit unit includes a chip pad, a top-layer trace connected to the chip pad is provided inside the silicon substrate, and the first ACF pad is a pad provided on the top-layer trace. 7.The ultrasonic fingerprint identification device according to claim 6, 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. 8.The ultrasonic fingerprint identification device of claim 1, wherein, 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 meet 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; 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.

9. The ultrasonic fingerprint identification device according to any one of claims 1 to 8, characterized in that, 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. 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. 10.The ultrasonic fingerprint identification device of claim 9, wherein, The first connecting layer is provided with a first metal layer, and the second connecting layer is provided with a second metal layer. The thickness of the first metal layer and / or the second metal layer is between 3 μm and 30 μm. 11.The ultrasonic fingerprint identification device of claim 10, wherein, The first connecting layer is further provided with a first glue layer, the first glue layer is used for connecting the first metal layer and the display screen, the absorption rate of the first glue layer to visible light is greater than 70%, and the thickness of the first glue layer is between 3 μm and 30 μm.

12. The ultrasonic fingerprint identification device of claim 10, wherein, The second connecting layer is further provided with a second glue layer, the second glue layer is used for connecting the second metal layer and the piezoelectric transducer, and the thickness of the second glue layer is between 3 μm and 30 μm.

13. The ultrasonic fingerprint recognition device according to claim 9, characterized in that: The first flexible circuit board is arranged between the piezoelectric transducer and the display screen, and a first flexible substrate layer in the first flexible circuit board is multiplexed as the medium layer in the connecting medium layer.

14. The ultrasonic fingerprint identification device of claim 13, wherein, One side of the first flexible substrate layer towards the ultrasonic fingerprint sensor chip comprises a chip bonding area and a first ACF pressing area; The chip bonding area is provided with a first copper foil layer and a chip bonding glue layer, and the first copper foil layer and the chip bonding glue layer are multiplexed as the second connecting layer in the connecting medium layer; The first ACF pressing area is provided with a second copper foil layer and the second ACF pad electrically connected to the second copper foil layer.

15. The ultrasonic fingerprint device of claim 14, wherein, One side of the second copper foil layer towards the silicon substrate is further provided with a first ACF protective glue, the first ACF protective glue connects the side of the second ACF pad and the side of the silicon substrate.

16. The ultrasonic fingerprint recognition device according to claim 14, characterized in that: One side of the silicon substrate in the ultrasonic fingerprint sensor chip towards the first 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.

17. The ultrasonic fingerprint device of claim 16, wherein, The edge of the chip bonding area exceeds the edge of the effective identification area by more than 0.05 mm.

18. The ultrasonic fingerprint device of claim 14, wherein, The one side of the first flexible substrate layer facing the ultrasonic fingerprint sensor chip further comprises a second ACF compression area, the second ACF compression area is located on the side of the first ACF compression area away from the chip bonding area, and the second ACF compression area is provided with the second copper foil layer and the third ACF pad electrically connected to the second copper foil layer.

19. The ultrasonic fingerprint device of claim 18, wherein, The second flexible circuit board comprises a second flexible substrate layer, one side of the second flexible substrate layer facing the display screen comprises a third ACF compression area corresponding to the second ACF compression area, and the third ACF compression area is provided with a third copper foil layer and a fourth ACF pad electrically connected to the third copper foil layer.

20. The ultrasonic fingerprint device of claim 19, wherein, In the first flexible circuit board, the second copper foil layer is further provided with a second ACF protective glue on the side facing the second flexible circuit board, and the second ACF protective glue connects the side of the third ACF pad, the side of the fourth ACF pad and the side of the second flexible circuit board.

21. The ultrasonic fingerprint device of claim 19, wherein, In the second flexible circuit board, the third copper foil layer is further provided with a third ACF protective glue on the side facing the first flexible circuit board, and the third ACF protective glue connects the side of the third ACF pad, the side of the fourth ACF pad and the side of the first flexible circuit board.

22. The ultrasonic fingerprint device of claim 18, wherein, The one side of the first flexible substrate layer facing away from the ultrasonic fingerprint sensor chip comprises a display screen bonding area corresponding to the chip bonding area, the first ACF compression area and the second ACF compression area, and the first connecting layer is arranged in the display screen bonding area.

23. The ultrasonic fingerprint device of claim 22, wherein, The display screen bonding area covers the chip bonding area, the first ACF compression area and the second ACF compression area.

24. The ultrasonic fingerprint identification device according to any one of claims 1 to 8, wherein, The edges of at least part of the laminated layers in the connecting medium layer exceed the edges of the silicon substrate by more than 0.5mm. The ultrasonic fingerprint identification device further comprises a fixing glue, the fixing glue is arranged in the edge area of at least part of the laminated layers in the connecting medium layer, and the fixing glue surrounds the ultrasonic fingerprint sensor chip and covers at least part of the side of the ultrasonic fingerprint sensor chip.

25. The ultrasonic fingerprint device of claim 24, wherein, The edges of at least part of the laminated layers in the connecting medium layer exceed the edges of the silicon substrate by more than 0.5mm.

26. The ultrasonic fingerprint device of claim 24, wherein, The edges of at least the first connecting layer in the connecting medium layer exceed the edges of the silicon substrate.

27. The ultrasonic fingerprint device of claim 24, wherein, The ultrasonic fingerprint identification device further comprises a light shielding glue, the light shielding glue is arranged on the display screen and surrounds at least part of the laminated layers in the connecting medium layer.

28. The ultrasonic fingerprint device of claim 27, wherein, The width of the light shielding glue is greater than or equal to 0.1mm, and / or the light shielding glue has an absorption rate of visible light greater than or equal to 70%.

29. The ultrasonic fingerprint identification device according to any one of claims 1 to 8, wherein, At least part of the edges of the connecting medium layer are flush with at least part of the edges of the silicon substrate or at least part of the edges of the connecting medium layer are recessed by no more than 0.5mm compared with at least part of the edges of the silicon substrate. The ultrasonic fingerprint identification device further comprises a fixing glue, the fixing glue is arranged on the display screen, and the fixing glue surrounds the connecting medium layer and the ultrasonic fingerprint sensor chip and covers at least part of the side of the connecting medium layer and the ultrasonic fingerprint sensor chip.

30. The ultrasonic fingerprint device of claim 29, wherein, The width of the fixing glue is greater than or equal to 0.1 mm.

31. The ultrasonic fingerprint identification device according to any one of claims 1 to 8, wherein, The thickness of the ultrasonic fingerprint identification device is less than or equal to 500 μm.

32. The ultrasonic fingerprint identification device according to any one of claims 1 to 8, wherein, 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 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-foldable screen through the connecting medium layer.

33. The ultrasonic fingerprint device of claim 32, wherein, The edge of the buffer layer window is more than 0.1 mm beyond the edge of the connecting medium layer.

34. The ultrasonic fingerprint device of any one of claims 1-8, wherein, The display screen is a foldable screen, the lowermost layer of the foldable screen is a support layer, and the ultrasonic fingerprint identification device is attached to the support layer through the connecting medium layer.

35. An electronic device, comprising: The display screen is a foldable screen, the lowermost layer of the foldable screen is a support layer, and the ultrasonic fingerprint identification device is attached to the support layer through the connecting medium layer. The display screen is a foldable screen, the lowermost layer of the foldable screen is a support layer, and the ultrasonic fingerprint identification device is attached to the support layer through the connecting medium layer. The display screen is a foldable screen, the lowermost layer of the foldable screen is a support layer, and the ultrasonic fingerprint identification device is attached to the support layer through the connecting medium layer. The display screen is a foldable screen, the lowermost layer of the foldable screen is a support layer, and the ultrasonic fingerprint identification device is attached to the support layer through the connecting medium layer.

36. The electronic device of claim 35, wherein, The display screen is a foldable screen, the lowermost layer of the foldable screen is a support layer, and the ultrasonic fingerprint identification device is attached to the support layer through the connecting medium layer.

37. The electronic device of claim 35, wherein, ​

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