CN115641619A

CN115641619A - Ultrasonic fingerprint identification device and electronic equipment

Info

Publication number: CN115641619A
Application number: CN202211111836.XA
Authority: CN
Inventors: 熊峰; 刘凯; 张建文; 王胤
Original assignee: Shenzhen Goodix Technology Co Ltd
Current assignee: Shenzhen Goodix Technology Co Ltd
Priority date: 2022-09-13
Filing date: 2022-09-13
Publication date: 2023-01-24

Abstract

The embodiment of the application provides an ultrasonic fingerprint identification device and electronic equipment, which can have better performance. This ultrasonic fingerprint identification device sets up in order to realize ultrasonic fingerprint identification under the screen in electronic equipment's display screen below, and this ultrasonic fingerprint identification device includes: ultrasonic fingerprint sensor chip includes: the piezoelectric transducer comprises a silicon substrate and a piezoelectric transducer arranged on the silicon substrate; the circuit board is arranged below the ultrasonic fingerprint sensor chip and comprises a circuit board bonding pad, and the circuit board bonding pad is connected to a chip bonding pad in the circuit unit through a lead so as to realize the electric connection between the ultrasonic fingerprint sensor chip and the circuit board; connect the spacer layer, connect between piezoelectric transducer and the display screen of ultrasonic wave fingerprint sensor chip to for the lead wire provides the accommodation space of display screen below, connect the spacer layer and be used for transmitting the ultrasonic signal that piezoelectric transducer produced to the display screen, and transmit ultrasonic wave fingerprint signal to piezoelectric transducer.

Description

Ultrasonic fingerprint identification device and electronic equipment

Technical Field

The present application relates to the field of fingerprint identification technology, and more particularly, to an ultrasonic fingerprint identification apparatus and an electronic device.

Background

With the development of the consumer electronics industry, especially the development of mobile communication device displays towards the direction of a comprehensive screen, the demand of consumers for the technology of fingerprint identification under the screen is increased or decreased. There are two main types of fingerprint identification schemes under the screen that have been disclosed: the first is an optical scheme and the second is an ultrasonic scheme. The performance of the optical fingerprint identification device is greatly influenced by the light transmittance of the screen, and with the improvement of the complexity of wiring inside the display screen and the development of factors such as a flexible screen scheme and the like, the optical transmittance of the screen is reduced, so that the optical fingerprint scheme cannot meet the application scenes. The ultrasonic fingerprint identification device does not depend on the optical transmissivity of the screen, and is a better alternative.

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 a technical problem to be solved urgently.

Disclosure of Invention

The embodiment of the application provides an ultrasonic fingerprint identification device and electronic equipment, which can have better performance.

The first aspect provides an ultrasonic fingerprint identification device, sets up in order to realize ultrasonic fingerprint identification under the screen in electronic equipment's display screen below, and this ultrasonic fingerprint identification device includes: ultrasonic fingerprint sensor chip includes: the piezoelectric transducer is used for sending an ultrasonic signal to a finger pressed on the display screen and receiving an ultrasonic fingerprint signal returned by the finger, and the substrate comprises a circuit unit which is electrically connected to the upper electrode and the lower electrode so as to control the piezoelectric transducer to generate the ultrasonic signal and detect the ultrasonic fingerprint signal for fingerprint identification; the circuit board is arranged below the ultrasonic fingerprint sensor chip and comprises a circuit board bonding pad, and the circuit board bonding pad is connected to a chip bonding pad in the circuit unit through a lead so as to realize the electric connection between the ultrasonic fingerprint sensor chip and the circuit board; connect the spacer layer, connect between the piezoelectric transducer and the display screen of ultrasonic wave fingerprint sensor chip to for the lead wire provides the accommodation space of display screen below, connect the spacer layer and be used for transmitting the ultrasonic signal that piezoelectric transducer produced to the display screen, and transmit ultrasonic wave fingerprint signal to piezoelectric transducer.

In the technical scheme of this application embodiment, an ultrasonic fingerprint identification device including ultrasonic fingerprint sensor chip, circuit board and connection wall is provided, wherein, COB encapsulation can be realized with the circuit board to this ultrasonic fingerprint sensor chip, and its reliability is high and the volume production nature is good, is favorable to improving ultrasonic fingerprint identification device's reliability and production efficiency. In addition, the ultrasonic fingerprint sensor chip can be only provided with the chip bonding pad with smaller area to realize the electric connection with the circuit board, is favorable to reducing the area of this ultrasonic fingerprint sensor chip to save the required space that occupies of ultrasonic fingerprint identification device below the display screen.

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

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

In some possible embodiments, the connecting spacer layer includes: the piezoelectric transducer comprises a first connecting layer, a spacing layer and a second connecting layer, wherein the first connecting layer is connected with the display screen and the spacing layer, and the second connecting layer is connected with the spacing layer and the piezoelectric transducer; the material of the spacing layer is organic polymer material, and/or the thickness of the spacing layer is between 10 μm and 200 μm. In some possible embodiments, the first connection layer comprises: the display screen comprises a first metal layer, a first adhesive layer and a second adhesive layer, wherein the first adhesive layer is connected with the display screen and the first metal layer, and the second adhesive layer is connected with the first metal layer and a spacing layer; the second connection layer includes: the second metal layer, the third adhesive layer and the fourth adhesive layer, the third adhesive layer is connected to the spacing layer and the second metal layer, and the fourth adhesive layer is connected to the second metal layer and the piezoelectric transducer.

In some possible embodiments, the absorption of visible light by the first glue layer is greater than 70%, and/or the thickness of the first glue layer is between 3 μm and 30 μm.

In some possible embodiments, the thickness of the fourth glue layer is between 3 μm and 30 μm.

In some possible embodiments, the thickness of the first adhesive layer is greater than that of the second adhesive layer, and/or the thickness of the fourth adhesive layer is greater than that of the third adhesive layer.

In some possible embodiments, the circuit board is a flexible circuit board, the flexible circuit board including: the ultrasonic fingerprint sensor comprises a circuit layer and a reinforcing layer arranged below the circuit layer, wherein a window is formed in the circuit layer, and an ultrasonic fingerprint sensor chip is arranged in the window and fixed on the reinforcing layer; the chip bonding pad of the ultrasonic fingerprint sensor chip is located in the edge area of the silicon substrate, and the circuit board bonding pad of the flexible circuit board is located in the edge area of the window in the circuit layer.

In some possible embodiments, the connection spacer layer covers the window, and the connection spacer layer is connected between the piezoelectric transducer of the ultrasonic fingerprint sensor chip and the display screen and between the circuit layer and the display screen.

In some possible embodiments, foam is disposed in the peripheral region of the window in the circuit layer, and the connection spacer layer is connected between the circuit layer and the display screen through the foam.

In some possible embodiments, a receiving area facing the lead lines is formed in the connection spacer layer, and the receiving area provides a receiving space under the display screen for the lead lines.

In some possible embodiments, the first connection layer in the connection spacer layer is a continuous structure, and the spacer layer in the connection spacer layer and the second connection layer are formed with through holes to form the accommodation region in the connection spacer layer.

In some possible embodiments, the first connection layer, the spacer layer and the second connection layer in the connection spacer layer are formed with through holes to form a receiving area in the connection spacer layer. Meanwhile, the lead is covered with black protective glue, and the black protective glue can completely cover the lead area, so that the influence of the reflection of the lead under strong light on the display effect is avoided.

In some possible embodiments, the edges of at least some of the stacks in the connection spacer layer extend beyond the edges of the circuit board; the ultrasonic fingerprint recognition device further includes: and the fixing glue is arranged in the edge area of at least part of the laminated layers in the connecting spacing layer, surrounds the circuit board and coats at least part of the side face of the circuit board. In some possible embodiments, the edges of at least some of the stacks in the connecting spacer layer extend more than 0.5mm beyond the edges of the circuit board.

In some possible embodiments, an edge of at least the first connection layer in the connection spacer layer extends beyond an edge of the circuit board.

In some possible embodiments, the ultrasonic fingerprint recognition device further includes: and the shading glue is arranged on the display screen and surrounds the periphery of the connecting spacing layer. The shading adhesive can be a UV curing adhesive, a heat curing adhesive, a Pressure Sensitive Adhesive (PSA) or a thermoplastic ink layer, and the absorptivity of the shading adhesive to visible light is more than or equal to 70%.

In some possible embodiments, the width of the light blocking glue is greater than or equal to 0.1mm.

In some possible embodiments, the edge of the connection spacing layer is flush with the edge of the circuit board or the edge of the connection spacing layer is recessed within 0.5mm compared with the edge of the circuit board, and the ultrasonic fingerprint identification device further comprises: and the fixing glue is arranged on the display screen, surrounds the connecting spacing layer and the circuit board and covers at least part of the side surfaces of the connecting spacing layer and the circuit board.

In some possible embodiments, the width of the fixing glue is greater than or equal to 0.1mm.

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

In some possible embodiments, the display screen is an unfolded screen, the lowest layer of the unfolded screen is a buffer layer, a buffer layer window is formed in the buffer layer, and the ultrasonic fingerprint identification device is arranged in the buffer layer window and is attached to the substrate layer, located above the buffer layer, in the unfolded screen through the connecting spacer layer.

In some possible embodiments, the edge of the buffer layer window extends more than 0.1mm beyond the edge of the connecting spacer layer.

In some possible embodiments, the display screen is a folding screen, the lowest layer of the folding screen is a supporting layer, and the ultrasonic fingerprint identification device is attached to the supporting layer through a connecting spacer layer.

In a second aspect, an electronic device is provided, comprising: a display screen and the ultrasonic fingerprint identification device according to the first aspect or any one of the first aspects, wherein the display screen is used for providing a pressing interface of a finger and receiving the pressing of the finger; the ultrasonic fingerprint identification device is arranged below the display screen and used for identifying the fingerprint of the finger pressing the display screen.

In some possible embodiments, the display screen is an unfolded screen, the lowest layer of the unfolded screen is a buffer layer, a buffer layer window is formed in the buffer layer, and the ultrasonic fingerprint identification device is arranged in the buffer layer window and attached to a substrate layer above the buffer layer in the unfolded screen.

In some possible embodiments, the display screen is a folding screen, the lowermost layer of the folding screen is a supporting layer, and the ultrasonic fingerprint identification device is attached to the supporting layer.

Drawings

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

Fig. 2 is another schematic structural diagram of an ultrasonic fingerprint identification device provided in an embodiment of the present application.

Fig. 3 is another schematic structural diagram of an ultrasonic fingerprint identification device provided in an embodiment of the present application.

Fig. 4 is another schematic structural diagram of an ultrasonic fingerprint identification device provided in an embodiment of the present application.

FIG. 5 is a schematic top view of the ultrasonic fingerprint identification device in the embodiment of FIG. 4.

Fig. 6 is another schematic structural diagram of an ultrasonic fingerprint identification device according to an embodiment of the present application.

FIG. 7 is a schematic top view of the ultrasonic fingerprint identification device in the embodiment of FIG. 6.

Fig. 8 is a schematic structural diagram of an ultrasonic fingerprint identification device provided in an embodiment of the present application under an unfolded screen.

Fig. 9 is another schematic structural diagram of an ultrasonic fingerprint identification device provided in an embodiment of the present application under an unfolded screen.

Fig. 10 is a schematic structural diagram of an ultrasonic fingerprint identification device provided in an embodiment of the present application under a folding screen.

Fig. 11 is another schematic structural diagram of an ultrasonic fingerprint identification device provided in an embodiment of the present application under a folding screen.

Detailed Description

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

The technical scheme of this application can be applied to ultrasonic fingerprint detection device. As a common application scenario, the ultrasonic fingerprint detection device provided by the embodiment of the application can be applied to smart phones, tablet computers, intelligent wearable devices, intelligent door locks or other types of electronic devices. More specifically, in the above electronic device, the ultrasonic fingerprint detection device may be disposed on any side of the electronic device that interacts with the user, including but not limited to the front side of the electronic device.

Fig. 1 is a schematic structural diagram illustrating an ultrasonic fingerprint identification device 10 according to an embodiment of the present application. The ultrasonic fingerprint identification device 10 can be disposed below a display screen 20 of an electronic device to realize the under-screen ultrasonic fingerprint identification.

As shown in fig. 1, the ultrasonic fingerprint recognition device 10 includes: an ultrasonic fingerprint sensor chip 100, a circuit board 200, and a connection spacer 300.

Specifically, the ultrasonic fingerprint sensor chip 100 includes: the ultrasonic fingerprint detection device comprises a silicon substrate 110 and a piezoelectric transducer 120 arranged on the silicon substrate 110, wherein the piezoelectric transducer 120 comprises a piezoelectric layer 122, an upper electrode 121 positioned above the piezoelectric layer 122, and a lower electrode 123 positioned below the piezoelectric layer 122, and the piezoelectric transducer 120 is used for sending an ultrasonic signal 22 to a finger 21 pressed on the display screen 20 and receiving an ultrasonic fingerprint signal 23 returned by the finger 21. The silicon substrate 110 includes a circuit unit 111, and the circuit unit 111 is electrically connected to the upper electrode 121 and the lower electrode 123 to control the piezoelectric transducer 120 to generate the ultrasonic wave signal 22 and detect the ultrasonic wave fingerprint signal 23 for fingerprint recognition.

The circuit board 200 is disposed below the ultrasonic fingerprint sensor chip 100, and includes a circuit board pad 201, the circuit board pad 201 is connected to the chip pad 101 of the circuit unit 111 through a lead 202, and the circuit unit 111 of the silicon substrate 110 is electrically connected to the circuit board 200 through the chip pad 101 and the lead 202.

The connection spacer layer 300 is connected between the piezoelectric transducer 120 of the ultrasonic fingerprint sensor chip 100 and the display screen 20, and the connection spacer layer 300 is used for transmitting the ultrasonic wave signal 22 generated by the piezoelectric transducer 120 to the display screen 20 and transmitting the ultrasonic fingerprint signal 23 to the piezoelectric transducer 120.

Specifically, in the embodiment of the present application, the ultrasonic fingerprint sensor chip 100 is a dedicated chip for performing ultrasonic fingerprint imaging. As an example, the ultrasonic fingerprint sensor chip 100 may be a Complementary Metal-Oxide-Semiconductor (CMOS) chip.

In the ultrasonic fingerprint sensor chip 100, the Circuit unit 111 disposed on the silicon substrate 110 may be an Application Specific Integrated Circuit (ASIC) for fingerprint recognition. The circuit unit 111 is capable of energizing a piezoelectric transducer 120 located thereabove to generate an ultrasonic signal 22 to a finger 21 pressed against the display screen 20. This ultrasonic wave signal 22 forms the ultrasonic wave fingerprint signal 23 that carries with fingerprint information after 21 reflection of finger, and piezoelectric transducer 120 processes the conversion to this ultrasonic wave fingerprint signal 23 and obtains the fingerprint signal of telecommunication, and circuit element 111 can carry out the fingerprint formation of image in order to carry out fingerprint identification to this fingerprint signal of telecommunication.

Specifically, the circuit unit 111 is electrically connected to the upper electrode 121 and the lower electrode 123 of the piezoelectric transducer 120. In performing fingerprint recognition, the circuit unit 111 outputs an excitation signal, such as a sine wave or a pulse wave, and the like, and applies the excitation signal to the upper electrode 121 and the lower electrode 123, and the circuit unit 111 may control the frequency and amplitude thereof. Under the excitation signal, the piezoelectric layer 122 vibrates based on the piezoelectric effect, thereby emitting the ultrasonic signal 22 to the finger 21. The ultrasonic fingerprint signal 23 formed by the ultrasonic signal 22 after being reflected by the finger 21 is transmitted to the piezoelectric layer 122, based on the inverse piezoelectric effect, a potential difference is generated between the upper electrode 121 and the lower electrode 123, so as to obtain a corresponding fingerprint electrical signal, and the circuit unit 111 obtains the fingerprint electrical signal and processes the fingerprint electrical signal, so as to obtain the fingerprint pattern of the finger 21.

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

For example, as shown in fig. 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 will generate an electrical signal between each electrode in the electrode array of the upper electrode 121 and the lower electrode 123, and the electrical signal corresponding to each electrode can be acquired and processed individually as a pixel value of one pixel in the fingerprint pattern.

The upper electrode 121 may be formed on the upper surface of the piezoelectric layer 122 by sputtering, for example, and may be a metal layer or a metal paste coating; the lower electrode 123 may be formed on the lower surface of the piezoelectric layer 122 by sputtering, evaporation, or the like, and may be made of aluminum or gold.

Further, optionally, the surface of the upper electrode 121 and/or the lower electrode 123 may be further covered with a passivation layer to electrically isolate the piezoelectric transducer 120 from other dielectric layers except the circuit unit 111.

With continued reference to fig. 1, in order to achieve the above-mentioned electrical connection between the ultrasonic fingerprint sensor chip 100 and an external electrical device, in the embodiment of the present application, a circuit board 200 is disposed below the ultrasonic fingerprint sensor chip 100, the ultrasonic fingerprint sensor chip 100 may be fixedly disposed on an upper surface of the circuit board 200, for example, the ultrasonic fingerprint sensor chip 100 may be fixedly disposed on the upper surface of the circuit board 200 through a Die Attach Film ((DAF) or other types of Die Attach films).

The Circuit Board 200 may be a Printed Circuit Board (PCB), a Flexible Circuit Board (FPC), or a rigid-flex Circuit Board. The circuit board 200 is provided therein with a circuit board pad 201, which may be connected to the chip pad 101 of the ultrasonic fingerprint sensor chip 100 through a wire 202, thereby achieving electrical connection between the circuit board 200 and the ultrasonic fingerprint sensor chip 100. Through the circuit board 200, the fingerprint image signal detected by the ultrasonic fingerprint sensor chip 100 can be conveniently transmitted to other components, such as a processor, for processing through the circuit board 200.

Alternatively, the chip pad 101 may be formed in the silicon substrate 110 through a chip manufacturing process. Specifically, the die pad 101 may be a portion of a circuit unit 111 in the silicon substrate 110, which may be electrically connected with other circuits in the circuit unit 111 to realize transmission of electrical signals.

Alternatively, the number of the chip pads 101 may be plural, and a part of the chip pads 101 in the plural chip pads 101 may be electrically connected to other circuits in the circuit unit 111, and another part of the chip pads 101 may be connected to the upper electrodes 121 of the piezoelectric transducers 120. In this embodiment, the upper electrode 121 of the piezoelectric transducer 120 is connected to a circuit board pad 201 on the circuit board 200 by a wire 202 connected to the chip pad 101, and the upper electrode 121 of the piezoelectric transducer 120 may receive an excitation signal transmitted by the circuit board 200.

By way of example and not limitation, the connection between the die pad 101 and the circuit board pad 201 may be achieved through a Wire Bonding (WB) process, and the Wire 202 between the die pad 101 and the circuit board pad 201 includes, but is not limited to, gold Wire.

In some ultrasonic fingerprint sensor chips formed on a glass substrate by a Thin Film Transistor (TFT) process, the metal density of the upper electrode is generally low, and the chip does not support a Wire Bonding (WB) process, but needs to be connected with other electrical devices by other processes, such as an Anisotropic Conductive Film (ACF) process, resulting in high overall cost.

In the embodiment of the present application, the connection between the upper electrode 121 and the die pad 101 may be implemented in the ultrasonic fingerprint sensor chip 100, and then the interconnection between the die pad 101 and the circuit board pad 201 on the circuit board 200 may be implemented through a wire bonding process. By the embodiment, the interconnection between the upper electrode 121 and the circuit board 200 can be realized, the process is easy to realize, and the reliability is high.

In summary, according to the technical solution of the embodiment, the ultrasonic fingerprint sensor Chip 100 can be connected to the circuit Board 200 through the leads 202, and the ultrasonic fingerprint sensor Chip 100 can be packaged in a Chip On Board (COB) package. The packaging method has high reliability and good mass production, and is beneficial to improving the reliability and the production efficiency of the ultrasonic fingerprint identification device 10. In addition, the ultrasonic fingerprint sensor chip 100 can be electrically connected to the circuit board 200 only by the chip pad 101 with a small area, which is beneficial to reducing the area of the ultrasonic fingerprint sensor chip 100, thereby reducing the overall area of the ultrasonic fingerprint identification device 10 and being beneficial to saving the space occupied by the ultrasonic fingerprint identification device 10 below the display screen 20.

With continued reference to FIG. 1, to implement the installation of the ultrasonic fingerprint identification device 10 under the display screen 20, the present embodiment further includes a connection spacer layer 300, the connection spacer layer 300 is connected between the piezoelectric transducer 120 of the ultrasonic fingerprint sensor chip 100 and the display screen 20, so as to provide 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.

Optionally, since the ultrasonic fingerprint sensor chip 100 needs to be electrically connected to the circuit board 200 through the lead 202, the lead 202 has a certain arc height, and the highest point of the lead 202 is higher than the upper surface of the ultrasonic fingerprint sensor chip 100, therefore, adding the connection spacer layer 300 between the ultrasonic fingerprint sensor chip 100 and the display screen 20 may be convenient to provide a certain accommodation space for the lead 202 below the display screen 20.

Through the technical scheme of the embodiment, the connection spacer layer 300 not only can be used for mounting the ultrasonic fingerprint sensor chip 100 and the circuit board 200 below the display screen 20, but also can provide a transmission medium for the ultrasonic signal 22 and the ultrasonic fingerprint signal 23, thereby ensuring the fingerprint identification performance of the ultrasonic fingerprint identification device 10. Further, the connection spacer 300 may also provide a receiving space for the leads 202 connected to the ultrasonic fingerprint sensor chip 100 and the circuit board 200, so as to prevent the leads 202 from interfering with the display 20, thereby further ensuring the reliability of the ultrasonic fingerprint identification device 10.

To sum up, in the technical scheme of this application embodiment, provide an ultrasonic fingerprint identification device 10 including ultrasonic fingerprint sensor chip 100, circuit board 200 and connection spacer layer 300, wherein, COB encapsulation can be realized with circuit board 200 to this ultrasonic fingerprint sensor chip 100, and its reliability is high and the volume production nature is good, is favorable to improving reliability and production efficiency of ultrasonic fingerprint identification device 10. In addition, the ultrasonic fingerprint sensor chip 100 can be electrically connected to the circuit board 200 only by the chip pad 101 with a small area, which is beneficial to reducing the area of the ultrasonic fingerprint sensor chip 100, so that the space occupied by the ultrasonic fingerprint identification device 10 below the display screen 20 is saved.

Alternatively, in some embodiments, the thickness of the silicon substrate 110 in the ultrasonic fingerprint sensor chip 100 may be between 50 μm and 300 μm, for example, may be between 50 μm and 160 μm, that is, greater than or equal to 50 μm and less than or equal to 160 μm. When silicon is used as a substrate material, the thickness of the silicon substrate 110 affects the resonance frequency of the piezoelectric layer 122 in the piezoelectric transducer 120, and therefore, the thickness of the silicon substrate 110 is set between 50 μm and 300 μm, so that the influence of the silicon substrate 110 on the resonance frequency of the piezoelectric layer 122 can be minimized, and the fingerprint identification performance can be improved.

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

Alternatively, in some embodiments, the material of the piezoelectric layer 122 may be, for example, polyvinylidene fluoride (PVDF), or polyvinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE).

The thickness of the piezoelectric layer 122 also affects the resonant frequency thereof, and for this reason, in one implementation, the thickness of the piezoelectric layer 122 is between 4 μm and 40 μm, i.e., the thickness of the piezoelectric layer 122 is greater than or equal to 4 μm and less than or equal to 40 μm, so that the resonant frequency of the piezoelectric layer 122 is within a frequency range suitable for fingerprint identification, thereby further improving the performance of fingerprint identification.

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 resonant frequency of the piezoelectric layer 122 can meet the requirement of fingerprint identification.

Fig. 2 shows another schematic structure diagram of the ultrasonic fingerprint identification device 10 provided in the embodiment of the present application.

As shown in fig. 2, in the present embodiment, the connection spacer layer 300 may include: a first connection layer 310, a spacer layer 330, and a second connection layer 320, wherein the first connection layer 310 is connected to the display 20 and the spacer layer 330, and the second connection layer 320 is connected to the spacer layer 330 and the piezoelectric transducer 120. The material of the spacer layer 330 is an organic polymer material, and/or the thickness of the spacer layer 330 is between 10 μm and 200 μm.

Specifically, in order to ensure the transmission of the ultrasonic wave between the piezoelectric transducer 120 and the display screen 20 and reduce the transmission loss thereof, a spacer layer 330 may be disposed in the connection spacer layer 300, and the spacer layer 330 may be a dielectric layer matched with the display screen 20 and the piezoelectric transducer 120. For example, to maximize signal propagation through the spacer layer 330For good transmission performance, the acoustic impedance of the stack adjacent to spacer layer 330 may be considered. When the acoustic impedances of the adjacent stacks on both sides of the spacer layer 330 are Z1 and Z2, respectively, the acoustic impedance of the spacer layer 330 is equal to

Optimal acoustic impedance matching can be achieved between the spacer layer 330 and its adjacent stacks. Here, the acoustic impedance Z is an important index for evaluating signal transmission in the spacer layer 330, Z = ρ c, ρ is the material density of the spacer layer 330, and c is the transmission speed of the ultrasonic wave, i.e., the sound velocity. For solid materials, the sound velocity c is related to its mechanical parameters, and satisfies

Wherein Y is Young modulus, and ν is Poisson's ratio.

As an example, in order to match the stack of layers in the display 20, the material of the spacer layer 330 may be an organic polymer material, such as polyethylene terephthalate (PET), polyimide (PI), thermoplastic Polyurethane (TPU), and the like. Alternatively, in some alternative embodiments, the material of the spacing layer 330 may also be an inorganic material, such as carbon fiber (carbon fiber) and glass, etc.

Meanwhile, the transmittance of the ultrasonic wave is also related to the material thickness, for example, it is found through experiments that when d = (2n + 1) × (λ/4) is satisfied between the thickness d of the spacer layer 330 and the wavelength λ of the ultrasonic wave, the signal attenuation is large; and d = λ/2, the influence on the signal transmission is small. Thus, in some implementations, the thickness of the spacer layer 330 may be between 10 μm and 200 μm, such as 50 μm.

In addition, through the thickness of the spacing layer 330, not only is the transmission of the ultrasonic waves by the spacing layer 330 facilitated, but also a certain gap is provided below the display screen 20 to accommodate the lead 202 for connecting the ultrasonic fingerprint sensor chip 100 and the circuit board 200, so that the lead 202 is prevented from interfering with the display screen 20.

Further, to achieve the connection of the spacer layer 330 to the display screen 20 and the piezoelectric transducer 120, the connecting spacer layer 300 further comprises: a first connection layer 310 and a second connection layer 320, which first connection layer 310 and second connection layer 320 may have glue layers to facilitate the connection of the spacer layer 330 between the piezoelectric transducer 120 and the display screen 20.

Optionally, in some embodiments, as shown in fig. 2, the piezoelectric transducer 120 may include, in addition to the upper electrode 121, the piezoelectric layer 122, and the lower electrode 123: and a passivation layer 124, wherein the passivation layer 124 covers the upper surface of the upper electrode 121. The protection layer 124 can be used to protect the upper electrode 121 from oxidation, and the protection layer 124 can also be used to protect the piezoelectric layer 122 to ensure its piezoelectric performance. By the protection layer 124, the permeation and failure behavior of the piezoelectric layer 122 and the upper electrode 121 under high temperature, high humidity, and the like can be avoided, thereby improving the safety and reliability of the ultrasonic fingerprint identification device 10.

The connecting spacer layer 300 may be used to connect the protective layer 124 to the display 20, based on the piezoelectric transducer 120 including the protective layer 124. Specifically, the second connection layer 320 in the connection spacer layer 300 is connected to the protection layer 124 and the display screen 20.

Optionally, in some embodiments, the first connection layer 310 may include: a first metal layer, a first adhesive layer and a second adhesive layer, wherein the first adhesive layer is connected to the display screen 20 and the first metal layer, and the second adhesive layer is connected to the first metal layer and the spacing layer 330. Similarly, the second connection layer 320 may include: a second metal layer, a third adhesive layer and a fourth adhesive layer, wherein the third adhesive layer is connected to the spacing layer 330 and the second metal layer, and the fourth adhesive layer is connected to the second metal layer and the piezoelectric transducer 120.

In this embodiment, the first connection layer 310 and the second connection layer 320 are both a three-layer structure, and the middle layer of the three-layer structure is a metal layer (i.e. the first metal layer and the second metal layer) including, but not limited to, a copper foil layer. The upper and lower surfaces of the metal layer are coated with glue layers so as to facilitate the interconnection of the metal layer and other laminated layers. Optionally, the thickness of the first metal layer is between 3 μm and 30 μm, and/or the thickness of the second metal layer is between 3 μm and 30 μm.

Through the technical scheme of this embodiment, the first connection layer 310 and the second connection layer 320 may be used to implement a connection function, two metal layers may also be matched with acoustic impedances of adjacent stacked layers, and the two metal layers may generate coherent superposition of ultrasonic waves, so as to further improve transmission performance of the first connection layer 310 and the second connection layer 320 to the ultrasonic waves, thereby improving fingerprint identification performance of the ultrasonic fingerprint identification device 10.

Optionally, the first adhesive layer in the first connection layer 310 is a low light-transmitting (e.g., black) adhesive layer. The absorptivity of the first adhesive layer to visible light is more than 70%, for example, the absorptivity of the first adhesive layer to visible light is between 70% and 90%. Specifically, the first adhesive layer is an adhesive layer of the first connecting layer 310 facing the display screen 20, and is used for connecting the display screen 20 and the first metal layer. The first adhesive layer is a low light-transmitting (e.g., black) adhesive layer, which can reduce or prevent the appearance problem caused by the ultrasonic fingerprint identification device 10 disposed below the display screen 20.

Optionally, the thickness of the first glue layer is between 3 μm and 30 μm. Through the thickness that sets up this first glue film, can guarantee that this first glue film has good and reliable adhesion, promote the installation reliability of ultrasonic fingerprint identification device 10 in display screen 20 below.

Similar to the thickness range of the first adhesive layer, the thickness of the second adhesive layer in the first connection layer 310 may also be between 3 μm and 30 μm, so as to ensure the adhesiveness of the second adhesive layer. In some possible embodiments, in order to reduce the thickness of the entire first connection layer 310, and thus the space of the ultrasonic fingerprint identification device 10 under the display screen 20, the thickness of the second adhesive layer may be reduced appropriately, that is, the thickness of the second adhesive layer may be smaller than the thickness of the first adhesive layer.

Optionally, in the second connection layer 320, the thickness of the fourth glue layer is located between 3 μm and 30 μm. Specifically, the fourth adhesive layer is an adhesive layer facing the ultrasonic fingerprint sensor chip 100, and is used for connecting the piezoelectric transducer 120 in the ultrasonic fingerprint sensor chip 100. In the manufacturing process of the ultrasonic fingerprint sensor chip 100, due to problems such as process, the ultrasonic fingerprint sensor chip 100 may warp, which affects the overall performance and the required occupied thickness space of the ultrasonic fingerprint identification device 10. In view of this, in the embodiment, by setting the thickness of the fourth adhesive layer, under the adhesion effect of the fourth adhesive layer, the warping degree of the ultrasonic fingerprint sensor chip 100 can be better absorbed, the overall performance of the ultrasonic fingerprint identification device 10 is improved, and the thickness space required to be occupied by the ultrasonic fingerprint identification device 10 under the display screen 20 is reduced.

Similar to the thickness range of the fourth adhesive layer, the thickness of the third adhesive layer in the second connection layer 320 may also be between 3 μm and 30 μm, so as to ensure the adhesiveness of the third adhesive layer. In some possible embodiments, in order to reduce the thickness of the second connection layer 320 and thus the space of the ultrasonic fingerprint identification device 10 below the display screen 20, the thickness of the third adhesive layer may be reduced appropriately, that is, the thickness of the third adhesive layer may be smaller than the thickness of the fourth adhesive layer.

Fig. 3 shows another schematic structure diagram of the ultrasonic fingerprint identification device 10 provided in the embodiment of the present application.

As shown in fig. 3, in the embodiment of the present application, the circuit board 200 is a flexible circuit board, and the flexible circuit board includes: the ultrasonic fingerprint sensor chip 100 includes a circuit layer 210 and a reinforcing layer 220 disposed below the circuit layer 210, wherein a window 211 is formed in the circuit layer 210, and the ultrasonic fingerprint sensor chip 100 is disposed in the window 211 and fixed to the reinforcing layer 220. The chip pad 101 of the ultrasonic fingerprint sensor chip 100 is located at an edge region of the silicon substrate 110, and the circuit board pad 201 of the flexible circuit board is located at an edge region of the window 211 in the circuit layer 210.

Specifically, in the embodiment of the present application, the circuit board 200 is a flexible circuit board FPC, which includes a circuit layer 210 and a reinforcing layer 220, wherein the circuit layer 210 includes a flexible substrate and a metal layer, a circuit board pad 201 may be formed in the metal layer, and the circuit board pad 201 is connected to the chip pad 101 of the ultrasonic fingerprint sensor chip 100 through a lead 202, so as to achieve electrical connection and electrical signal transmission between the FPC and the ultrasonic fingerprint sensor chip 100.

A reinforcing layer 220 is disposed below the circuit layer 210, and the reinforcing layer 220 includes, but is not limited to, a steel plate or other material layer with certain strength, and is used to support and reinforce the flexible circuit layer 210, so as to improve the reliability of the circuit layer 210, and further facilitate performing a wire bonding process on the circuit board pad 201 on the circuit layer 210 to form the wire 202.

The circuit layer 210 has a window 211 formed therein for accommodating the ultrasonic fingerprint sensor chip 100, and the ultrasonic fingerprint sensor chip 100 may be fixedly connected to the reinforcing layer 220 by an adhesive layer. Through the technical scheme of this embodiment, the whole thickness space of ultrasonic fingerprint sensor chip 100 and circuit board 200 can be reduced to save the space under the screen that ultrasonic fingerprint identification device 10 needs to occupy.

Further, the chip pad 101 of the ultrasonic fingerprint sensor chip 100 is located at an edge region of the silicon substrate 110, and the circuit board pad 201 of the FPC is located at an edge region of the window 211 in the circuit layer 210, so that the circuit board pad 201 is closer to the chip pad 101, thereby facilitating the electrical connection between the circuit board pad 201 and the chip pad 101 through the lead 202.

With continued reference to fig. 3, optionally, a connection spacer layer 300 covers the window 211, the connection spacer layer 300 being connected between the piezoelectric transducer 120 of the ultrasonic fingerprint sensor chip 100 and the display screen 20, and between the circuit layer 210 and the display screen 20.

Specifically, in this embodiment, the connection spacer layer 300 may be connected between the circuit layer 210 of the FPC and the display 20 instead of being connected between the piezoelectric transducer 120 and the display 20, so as to further enhance the installation strength of the ultrasonic fingerprint identification device 10 under the display 20 and enhance the usability of the ultrasonic fingerprint identification device 10.

Optionally, as shown in fig. 3, a foam 230 is disposed in a peripheral region of the window 211 in the circuit layer 210, and the connection spacer layer 300 is connected between the circuit layer 210 and the display screen 20 through the foam 230.

The foam 230 can provide a buffering effect between the connection spacer layer 300 and the circuit layer 210, and when a finger presses the display screen 20, the foam 230 can buffer the pressing of the finger, thereby preventing the display screen 20 from damaging the ultrasonic fingerprint identification device 10. In addition, the foam 230 may be in a compressed state, for example, the compression rate is greater than 50%, and the foam 230 in the compressed state may play a certain role in supporting and connecting the display screen 20, so as to prevent the display screen 20 from being subjected to a tensile stress, which may cause an appearance problem. Moreover, should enclose in the cotton 230 of bubble that the window 211 set up and circuit layer 210 and display screen 20 can form airtight space for hold ultrasonic fingerprint sensor chip 100 and lead wire 202, play sealed and guard action to this ultrasonic fingerprint sensor chip 100 and lead wire 202, thereby further promote the reliability in utilization of ultrasonic fingerprint identification device 10.

With continued reference to fig. 3, optionally, in the embodiment of the present application, a receiving area 301 facing the lead 202 may be formed in the connection spacer layer 300, and the receiving area 301 provides a receiving space under the display screen 20 for the lead 202.

Specifically, in the embodiment, the connection spacer 300 covers the window 211, and in order to prevent the connection spacer 300 from interfering and affecting the leads 202 at the window 211, the connection spacer 300 has a receiving region 301 facing the leads 202 to receive the top region of the leads 202, so as to ensure the reliability of the leads 202 and thus the reliability of the electrical connection between the ultrasonic fingerprint sensor chip 100 and the circuit layer 210.

Optionally, the accommodating area 301 in the connection spacer layer 300 may be a groove facing the lead 202, or may also be a through hole facing the lead 202. The embodiment of the present application does not limit the specific form of the accommodating area 301.

In some embodiments, the first connection layer 310 in the connection spacer layer 300 is a continuous structure, and the spacer layer 330 and the second connection layer 320 in the connection spacer layer 300 are formed with through holes to form the receiving region 301 in the connection spacer layer 300, and the first connection layer 310 is disposed over the leads 202.

Specifically, in this embodiment, the receiving area 301 can be regarded as a groove facing the leads 202 in the connecting spacer layer 300, and the first connecting layer 310 can completely cover the leads 202 and the components such as the ultrasonic fingerprint sensor chip 100 while receiving the leads 202. This embodiment can effectively prevent the problem of the appearance of the display screen 20, compared to the case where the first connection layer 310 is also formed with the through-holes.

Alternatively, as shown in fig. 3, in the accommodation area 301, in addition to the lead 202, a lead protection paste 203 for protecting the lead 202 may be accommodated. The lead protection adhesive 203 completely covers the lead 202, and can protect the lead 202 sufficiently. In the process of preparing the lead protective adhesive 203, a low temperature curing process may be used to cure the flowing adhesive to prevent the ultrasonic fingerprint sensor chip 100 from being affected by warpage and the like caused by a high temperature process, and the temperature of the low temperature curing process may be lower than or equal to 115 ℃.

In other possible embodiments, through holes are formed in the connection spacer layer 300 in the first connection layer 310, the spacer layer 330 and the second connection layer 320 to form the receiving area 301 in the connection spacer layer 300, and the leads 202 are covered with black protection glue.

Specifically, in this embodiment, the receiving area 301 can be regarded as a through hole facing the lead 202 in the connecting spacer 300, and the through hole can receive the lead 202 and the lead protection adhesive 203 covering the lead 202.

In order to prevent the lead wires 202 from causing an appearance problem of the display screen 20, the lead wire protection glue 203 of the lead wires 202 may be black protection glue to prevent the reflected light of the lead wires 202 from passing through the display screen 20 to affect the display effect.

In the above-mentioned application embodiment, the receiving area 301 for receiving the lead 202 is formed in the connecting spacer layer 300, and the lead 202 can be set by using the thickness of the connecting spacer layer 300, which is beneficial to saving the thickness space of the ultrasonic fingerprint identification device 10.

In other embodiments, where the ultrasonic fingerprinting device 10 has sufficient thickness space and/or the lead wires 202 have a small arc height, all of the layers in the connecting spacer layer 300 may be a continuous structure.

Fig. 4 shows another schematic structure diagram of the ultrasonic fingerprint identification device 10 provided in the embodiment of the present application.

As shown in fig. 4, in the embodiment of the present application, the edge of at least a part of the laminated layers in the connection spacer layer 300 exceeds the edge of the circuit board 200, and the ultrasonic fingerprint identification device 10 further includes: the fixing glue 400 is disposed on an edge region of at least a portion of the stacked layers in the connecting spacer layer 300, and the fixing glue 400 surrounds the circuit board 200 and covers at least a portion of a side surface of the circuit board 200.

By way of example, in the embodiment shown in fig. 4, all of the laminations in the connecting spacer layer 300 extend beyond the edge of the circuit board 200 in a direction parallel to the display screen 20. The fixing glue 400 is disposed on the lower surface of the connection spacer layer 300 and surrounds the edge region of the connection spacer layer 300. Meanwhile, the fixing glue 400 is further disposed around the side surface of the circuit board 200, and in a direction perpendicular to the display screen 20, the fixing glue 400 may cover at least a portion of the side surface of the circuit board 200, so as to fix the circuit board 200 and the ultrasonic fingerprint sensor chip 100 disposed on the circuit board 200 to the connection spacer layer 300.

Optionally, in the embodiment shown in fig. 4, the circuit board 200 includes the circuit layer 210 and the stiffening layer 220, and the fixing glue 400 may cover at least the side surface of the circuit layer 210 in the circuit board 200. Further, in the embodiment shown in fig. 4, the circuit board 200 is connected to the display screen 20 through the foam 230 and the connection spacer 300. The fixing glue 400 is disposed around the circuit board 200, and the fixing glue 400 is not only connected to the side of the circuit layer 210 in the circuit board 200, but also connected to the side of the foam 230.

Through the setting of this fixed glue 400, can promote the reliability of being connected of circuit board 200 and ultrasonic fingerprint sensor chip 100 and connection distance layer 300, and then further promote the reliability of being connected of ultrasonic fingerprint identification device 10 in display screen 20 below. In addition, since the fixing glue 400 is disposed on the connection spacer layer 300 and does not directly contact the display screen 20, when the ultrasonic fingerprint recognition device 10 is reworked and disassembled, the processing of the fixing glue 400 does not affect the display screen 20, and thus, the ultrasonic fingerprint recognition device 10 below the display screen 20 can be reworked conveniently by the technical solution of the embodiment.

Optionally, the fixing glue 400 may be an ultraviolet light curing glue (may be abbreviated as a UV curing glue), and the fixing glue 400 may be cured by ultraviolet light curing or ultraviolet light and moisture curing. Alternatively, the fixing glue 400 may be a glue layer cured at a low temperature (less than or equal to 100 ℃), and the glue layer may also be referred to as a heat-cured glue. The UV-curable glue or the heat-curable glue may be an epoxy material, for example. The fixing glue 400 is cured by the above curing methods, so that the display screen 20 and the ultrasonic fingerprint identification device 10 are prevented from being affected by high-temperature curing. In addition, the curing shrinkage rate of the fixing glue 400 may be equal to or greater than 3% to ensure the fixing effect of the fixing glue 400 on the ultrasonic fingerprint recognition device 10.

It should be noted that, in addition to the above technical solution that all the stacked layers in the connection spacing layer 300 exceed the circuit board 200 in the embodiment shown in fig. 4, in other alternative embodiments, only a part of the stacked layers in the connection spacing layer 300 may exceed the edge of the circuit board 200, for example, only the first connection layer 310 exceeds the edge of the circuit board 200, and the spacing layer 330 and the second connection layer 320 are flush with the edge of the circuit board 200. As another example, only the first connection layer 310 and the spacing layer 330 extend beyond the edge of the circuit board 200, while the second connection layer 320 is flush with the edge of the circuit board 200.

Compared with the technical scheme that part of the laminated layers exceed the edge of the circuit board 200, all the laminated layers in the connecting spacing layer 300 exceed the edge of the circuit board 200, and the size of all the laminated layers in the connecting spacing layer 300 in the direction parallel to the display screen 20 can be the same, so that the processing and manufacturing of the connecting spacing layer 300 are facilitated.

Optionally, in some embodiments, the edge of at least part of the stack of layers in the connecting spacer layer 300 exceeds the edge of the circuit board 200 by more than 0.5mm, i.e., the distance between the edge of at least part of the stack of layers in the connecting spacer layer 300 and the edge of the circuit board 200 is greater than or equal to 0.5mm.

As an example, the edge of at least the first connection layer 310 in the connection spacer layer 300 extends beyond the edge of the circuit board 200. Optionally, the edge of the first connection layer 310 exceeds the edge of the circuit board 200 by more than 0.5mm.

By the technical scheme of the embodiment, even if the connection spacing layer 300 and/or the circuit board 200 have manufacturing or installation tolerance, the connection spacing layer 300 and the circuit board 200 can be effectively connected, so that the installation reliability of the ultrasonic fingerprint identification device 10 below the display screen 20 is guaranteed. In addition, the connection spacer 300 may also completely cover the circuit board 200, thereby preventing the circuit board 200 and the ultrasonic fingerprint sensor chip 100 disposed above the circuit board 200 from being observed by a user through the display screen 20, so as to improve the appearance of the display screen 20.

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

With continued reference to fig. 4, in the embodiment of the present application, the ultrasonic fingerprint identification device 10 may further include: and the light shielding glue 500, wherein the light shielding glue 500 is disposed on the display screen 20 and surrounds the periphery of the connection spacer layer 300.

Specifically, the light shielding glue 500 may be a black glue layer to perform a good light shielding function. Further, the light shielding glue 500 is disposed around the connection spacer layer 300, and the entirety of the connection spacer layer 300 and the light shielding glue 500 can further cover the ultrasonic fingerprint sensor chip 100 and the circuit board 200 well, so as to more reliably solve the appearance problem caused by the arrangement of the ultrasonic fingerprint identification device 10 below the transparent layer of the display screen 20.

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

Alternatively, the light-shielding adhesive may be a Pressure Sensitive Adhesive (PSA), a UV curable adhesive, a heat curable adhesive, a UV curable adhesive, or a thermoplastic ink, among others. The thermosetting adhesive and the UV curable adhesive may be, for example, epoxy resin materials.

FIG. 5 shows a schematic top view of the ultrasonic fingerprint identification device 10 of the embodiment of FIG. 4.

As shown in fig. 5, the circuit board 200 may be a rectangular circuit board, the connection spacer 300 may also be a rectangular circuit board, the area of the connection spacer 300 may be larger than that of the circuit board 200, and the connection spacer 300 may cover the upper side of the circuit board 200. The length direction of the coupling spacer 300 is the same as the length direction of the circuit board 200, and the width direction of the coupling spacer 300 is the same as the width direction of the circuit board 200.

A distance D between the connection spacer 300 and the circuit board 200 in the length direction L of the circuit board 200 and the connection spacer 300 ₁ Greater than or equal to 0.5mm. Similarly, in the width direction W of the circuit board 200 and the connection spacer 300, the distance D between the connection spacer 300 and the circuit board 200 ₂ Greater than or equal to 0.5mm.

In addition, on the basis that the circuit board 200 and the connection spacer layer 300 are both rectangular, the fixing glue 400 and the light-shielding glue 500 may be both frame-type glue layers, wherein the light-shielding glue 500 is disposed around the connection spacer layer 300, and the width D of the light-shielding glue 500 is ₃ Greater than or equal to 0.1mm. The fixing glue 400 is disposed around the circuit board 200, and a gap may be disposed in the fixing glue 400 to avoid other components connected to the circuit board 200.

For example, as shown in fig. 5, an output board 204 may be connected to one end of the circuit board 200, the output board 204 is used for outputting an electrical signal of the circuit board 200, and the circuit board 200 may be conveniently connected to an external electrical device through the output board 204. In some embodiments, in the case that the circuit board 200 is an FPC, the output board 204 and the circuit layer 210 of the circuit board 200 may be an integral structure, i.e., the output board 204 and the circuit layer 210 are both circuit boards with flexible substrates.

In the case where the output board 204 is connected to one end of the circuit board 200, a gap may be formed in the fixing adhesive 400 to avoid the area of the output board 204, that is, the fixing adhesive 400 may surround the other area of the circuit board 200 except the area connected to the output board 204.

Fig. 6 shows another schematic structure diagram of the ultrasonic fingerprint identification device 10 provided in the embodiment of the present application.

As shown in fig. 6, in the embodiment of the present application, the edge of the connection spacer layer 300 is flush with the edge of the circuit board 200 or the edge of the connection spacer layer 300 is retracted within 0.5mm compared to the edge of the circuit board 200, and the ultrasonic fingerprint recognition device 10 further includes: the fixing glue 400 is disposed on the display screen 20, and the fixing glue 400 surrounds the connection spacer 300 and the circuit board 200 and covers at least a portion of the side surfaces of the connection spacer 300 and the circuit board 200 in the thickness direction.

By way of example, in the embodiment shown in fig. 6, all of the laminations in the connecting spacer layer 300 are flush with the edge of the circuit board 200 in a direction parallel to the display screen 20. The fixing glue 400 is disposed on the lower surface of the display panel 20 and surrounds the side surface of the connection spacer 300. Meanwhile, the fixing glue 400 is further disposed around the side surface of the circuit board 200, the thickness direction of the fixing glue 400 is perpendicular to the display screen 20, and in the thickness direction of the fixing glue 400, the fixing glue 400 can cover the side surface of the connection spacer layer 300 and at least a part of the side surface of the circuit board 200, so that the circuit board 200 and the ultrasonic fingerprint sensor chip 100 disposed on the circuit board 200 are fixed to the connection spacer layer 300 and the display screen 20.

Alternatively, in the embodiment shown in fig. 6, the circuit board 200 includes the circuit layer 210 and the reinforcing layer 220, and the fixing adhesive 400 may cover at least the side surface of the circuit layer 210 in the circuit board 200. Further, in the embodiment shown in fig. 6, the circuit board 200 is connected to the display screen 20 through the foam 230 and the connection spacer 300. The fixing glue 400 is disposed around the circuit board 200 and the connection spacer layer 300, and the fixing glue 400 is not only connected to the connection spacer layer 300 and the side of the circuit layer 210 in the circuit board 200, but also connected to the side of the foam 230.

Through the arrangement of the fixing glue 400, the connection reliability of the circuit board 200, the connection spacer layer 300 and the display screen 20 can be improved, and the connection reliability of the ultrasonic fingerprint identification device 10 below the display screen 20 is further improved. In addition, the fixing glue 400 is directly disposed on the lower surface of the display screen 20, and in some cases, the fixing glue 400 may be used as a light shielding glue to improve the appearance problem of the ultrasonic fingerprint identification device 10 under the display screen 20.

Alternatively, 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 0.1mm.

FIG. 7 shows a schematic top view of the ultrasonic fingerprint identification device 10 of the embodiment of FIG. 6.

Similar to fig. 5, as shown in fig. 7, the circuit board 200 may be a rectangular circuit board, and the fixing adhesive 400 disposed around the circuit board 200 may be a frame type. The width D of the fixing paste 400 in the length direction L and the width direction W of the circuit board 200 ₃ May be greater than or equal to 0.1mm.

In addition, in the embodiment shown in fig. 7, an output board 204 may also be disposed at one end of the circuit board 200, and the related technical solution of the output board 204 may refer to the related description of the embodiment shown in fig. 5, which is not described herein again.

Through the technical scheme of the above application embodiment, the thickness of each laminated layer in the ultrasonic fingerprint identification device 10 can be controlled, so that the whole thickness range of the ultrasonic fingerprint identification device 10 is less than or equal to 500 μm, and the installation thickness space required by the ultrasonic fingerprint identification device 10 below the display screen 20 is reduced.

In some embodiments, the ultrasonic fingerprint recognition device 10 may be disposed under an unfolded screen, i.e., the display screen 20 is an unfolded screen.

Fig. 8 shows a schematic structural diagram of the ultrasonic fingerprint identification device 10 provided in the embodiment of the present application under an unfolded screen.

As shown in fig. 8, the lowest layer of the non-folding screen is a buffer layer 24, a buffer layer window 241 is formed in the buffer layer 24, and the ultrasonic fingerprint identification device 10 is disposed in the buffer layer window 241 and attached to the substrate layer 25 above the buffer layer 24 in the non-folding screen through a connection spacer layer 300.

Alternatively, the substrate layer 25 may be an organic material layer, for example, the substrate layer 25 may be PI, and other circuit layers and light emitting layers of the display panel 20 are all prepared on the substrate layer 25. A buffer layer 24 is disposed below the substrate layer 25, and the buffer layer 24 may include: a foam layer, a copper foil layer and the like, for playing a role in buffering, shading, heat dissipation and the like on the display screen 20.

In order to reduce the installation space of the ultrasonic fingerprint identification device 10 under the non-folding screen and reduce the influence of Guan Dieceng in the buffer layer 24 on the fingerprint identification performance of the ultrasonic fingerprint identification device 10, a buffer layer window 241 may be formed in the buffer layer 24, and the ultrasonic fingerprint identification device 10 is installed under the display screen 20 by being disposed in the buffer layer window 241 and being connected to the substrate layer 25 through the connection spacer layer 300.

As shown in fig. 8, in this embodiment, the ultrasonic fingerprint identification device 10 may include a fixing adhesive 400 and a light shielding adhesive 500, wherein the fixing adhesive 400 is disposed on the connection spacer 300 for fixing the connection circuit board 200 and the connection spacer 300, and the light shielding adhesive 500 is disposed on the display screen 20 for surrounding the connection spacer 300 and playing a role of shielding light. Specifically, the related technical solution of the ultrasonic fingerprint identification device 10 can refer to the related description of the embodiments shown in fig. 4 and fig. 5, and will not be described in detail here.

In the embodiment of the present application, in order to prevent the optical signals of the structures such as the ultrasonic fingerprint sensor chip 100 and the circuit board 200 from being observed by the user through the buffer layer window 241, the light-shielding glue 500 may be disposed in the buffer layer window 241 and located at the edge region of the buffer layer window 241, and the whole of the light-shielding glue 500 and the connection spacer layer 300 may completely fill the buffer layer window 241, so as to improve and solve the appearance problem of the ultrasonic fingerprint identification device 10 under the non-folding screen.

Fig. 9 shows another schematic structure diagram of the ultrasonic fingerprint identification device 10 provided by the embodiment of the present application under the unfolded screen.

As shown in fig. 9, in this embodiment, the ultrasonic fingerprint identification device 10 may include a fixing adhesive 400, wherein the fixing adhesive 400 is disposed on the display screen 20 for fixedly connecting the circuit board 200 and the connecting spacer 300 to the display screen 20, and the fixing adhesive 400 is disposed around the connecting spacer 300 for shielding light. Specifically, the related technical solution of the ultrasonic fingerprint identification device 10 can refer to the related description of the embodiments shown in fig. 6 and fig. 7, and will not be described in detail here.

In the embodiment of the present application, in order to prevent the optical signals of the ultrasonic fingerprint sensor chip 100, the circuit board 200, and the like from being observed by the user through the buffer layer window 241, the fixing glue 400 may be disposed in the buffer layer window 241 and located at the edge region of the buffer layer window 241, and the whole of the fixing glue 400 and the connection spacer layer 300 may completely fill the buffer layer window 241, so as to improve and solve the appearance problem of the ultrasonic fingerprint identification device 10 under the non-folding screen.

Alternatively, in the embodiments of fig. 8 and 9 described above, the edges of the buffer layer window 241 may extend more than 0.1mm beyond the edges of the connecting spacer layer 300.

Specifically, in the case where the connection spacer layer 300 is rectangular, the buffer layer window 241 may also be a rectangular window adapted to the rectangular connection spacer layer 300. The area of the buffer layer window 241 may be larger than the area of the connection spacer layer 300, and the edge of the buffer layer window 241 may exceed the edge of the connection spacer layer 300 by more than 0.1mm, so as to facilitate the installation of the connection spacer layer 300 in the buffer layer window 241, and further facilitate the installation of the ultrasonic fingerprint identification device 10 in the buffer layer window 241 through the connection spacer layer 300.

Since the buffer layer window 241 and the connection spacer layer 300 have a gap of 0.1mm or more, the gap can be used for accommodating the light-shielding glue 500 shown in fig. 8 or the fixing glue 400 shown in fig. 9, so as to achieve a good light-shielding effect.

In other embodiments, the ultrasonic fingerprint identification device 10 may also be disposed under a folding screen, i.e., the display screen 20 is a folding screen.

Fig. 10 and 11 show two schematic structural diagrams of the ultrasonic fingerprint identification device 10 provided by the embodiment of the present application under a folding screen.

As shown in FIGS. 10 and 11, the lowest layer of the folding screen is a support layer 26, and the ultrasonic fingerprint recognition device 10 is attached to the support layer 26 through a connecting spacer layer 300. Alternatively, the support layer 26 may be a sheet of support steel, or other relatively strong support material.

In particular, due to the special requirement that the folding screen needs to be folded, the lowest layer of the folding screen needs to be provided with the supporting layer 26, and the supporting layer 26 cannot be windowed so as not to affect the folding performance of the folding screen. Therefore, in the case that the display 20 is a folding screen, the ultrasonic fingerprint recognition device 10 in the embodiment of the present application can be directly connected to the bottommost layer of the folding screen, i.e., the support layer 26, through the connection spacer layer 300.

Since the bottom layer of the folding screen is provided with the supporting layer 26, the ultrasonic fingerprint recognition device 10 is disposed under the display screen 20 without considering the appearance problem. As shown in fig. 10, in case that the edge of the connection spacer layer 300 is beyond the edge of the circuit board 200, the ultrasonic fingerprint recognition device 10 may include only the fixing glue 400 without including the light shielding glue 500. The specific scheme of the ultrasonic fingerprint identification device 10 in this embodiment may refer to the descriptions in fig. 4 and fig. 5 except for the light-shielding glue 500, which are not described in detail herein.

In the case where the edge of the connection spacer layer 300 is flush with the edge of the circuit board 200, as shown in fig. 11, the ultrasonic fingerprint recognition device 10 can also be fixedly connected to the support layer 26 directly by the fixing glue 400. The specific scheme of the ultrasonic fingerprint identification device 10 in this embodiment can be referred to the related description in fig. 6 and fig. 7, and will not be described in detail herein.

The embodiment of the present application further provides an electronic device, which includes a display screen 20 and the ultrasonic fingerprint identification apparatus 10 in any of the above embodiments. The display screen is used for providing a pressing interface of a user finger and receiving the pressing of the user finger. The ultrasonic fingerprint recognition device 10 is disposed below the display screen 20 and is used for recognizing the fingerprint of the finger of the user pressing on the display screen 20.

Optionally, the electronic device includes, but is not limited to, a mobile terminal device, such as: cell phones, notebook computers, tablet computers, and the like.

Optionally, the electronic device may further include a battery, which is also disposed below the display screen 20. In the embodiment of the present application, since the thickness of the ultrasonic fingerprint recognition device 10 is relatively thin, the ultrasonic fingerprint recognition device 10 can be disposed between the battery and the display 20. By the technical scheme of the embodiment, the installation space occupied by the ultrasonic fingerprint identification device 10 in the electronic equipment can be saved.

In some embodiments, the display 20 may be an unfolded screen, and the lowest layer of the unfolded screen is a buffer layer, and a buffer layer window is formed in the buffer layer, and the ultrasonic fingerprint identification device 10 is disposed in the buffer layer window and attached to a substrate layer above the buffer layer in the unfolded screen.

Specifically, the technical solutions of the embodiments shown in fig. 8 and fig. 9 may be referred to in the related technologies of the non-folding screen and the ultrasonic fingerprint identification device 10 in this embodiment, and redundant description is not repeated here.

In other embodiments, the display 20 may be a foldable screen, and the lowest layer of the foldable screen is a support layer to which the ultrasonic fingerprint recognition device 10 is attached.

Specifically, the technical solutions of the embodiment shown in fig. 10 and fig. 11 above may be referred to in the related art of the folding screen and the ultrasonic fingerprint identification device 10 in this embodiment, and redundant description is not repeated here.

It should be understood that the specific examples in the embodiments of the present application are for the purpose of promoting a better understanding of the embodiments of the present application and are not intended to limit the scope of the embodiments of the present application.

For example, the various features described in the foregoing detailed description may be combined in any suitable manner without contradiction, and various combinations that may be possible are not described in this application in order to avoid unnecessary repetition.

For example, various embodiments of the present application may be arbitrarily combined with each other, and the same should be considered as the disclosure of the present application as long as the concept of the present application is not violated.

It is to be understood that the terminology used in the embodiments of the present application and the appended claims is for the purpose of describing particular embodiments only and is not intended to be limiting of the embodiments of the present application. For example, as used in the examples of this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

Those of ordinary skill in the art will appreciate that the elements of the examples described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the components and steps of the examples have been described above generally in terms of their functionality in order to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the technical solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

In the several embodiments provided in the present application, it should be understood that the disclosed system and apparatus may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the modules is only one logical functional division, and other divisions may be realized in practice, for example, a plurality of modules or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or modules, and may also be an electrical, mechanical or other form of connection.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. The utility model provides an ultrasonic fingerprint identification device, its characterized in that sets up in order to realize ultrasonic fingerprint identification under the screen in electronic equipment's display screen below, ultrasonic fingerprint identification device includes:

ultrasonic fingerprint sensor chip includes: the ultrasonic fingerprint identification device comprises a silicon substrate and a piezoelectric transducer arranged on the silicon substrate, wherein the piezoelectric transducer comprises a piezoelectric layer, an upper electrode positioned above the piezoelectric layer and a lower electrode positioned below the piezoelectric layer, the piezoelectric transducer is used for sending an ultrasonic signal to a finger pressed on the display screen and receiving an ultrasonic fingerprint signal returned by the finger, and the silicon substrate comprises a circuit unit which is electrically connected to the upper electrode and the lower electrode so as to control the piezoelectric transducer to generate the ultrasonic signal and detect the ultrasonic fingerprint signal for fingerprint identification;

the circuit board is arranged below the ultrasonic fingerprint sensor chip and comprises a circuit board bonding pad, and the circuit board bonding pad is connected to a chip bonding pad in the circuit unit through a lead so as to realize the electric connection between the ultrasonic fingerprint sensor chip and the circuit board;

connect the spacer layer, connect in the piezoelectric transducer of ultrasonic wave fingerprint sensor chip with between the display screen, connect the spacer layer be used for with the ultrasonic signal transmission that piezoelectric transducer produced extremely the display screen, and will ultrasonic wave fingerprint signal transmission extremely piezoelectric transducer.

2. The ultrasonic fingerprint recognition device of claim 1, wherein the thickness of the silicon substrate is between 50 μ ι η and 300 μ ι η.

3. The ultrasonic fingerprint identification device according to claim 1, wherein 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.

4. The ultrasonic fingerprint recognition device according to claim 1, wherein said connection spacer layer comprises: the piezoelectric transducer comprises a first connecting layer, a spacing layer and a second connecting layer, wherein the first connecting layer is connected with the display screen and the spacing layer, and the second connecting layer is connected with the spacing layer and the piezoelectric transducer;

the spacer layer is made of an organic polymer material, and/or the thickness of the spacer layer is between 10 and 200 micrometers.

5. The ultrasonic fingerprint identification device of claim 4, wherein the first connection layer comprises: the display screen comprises a first metal layer, a first adhesive layer and a second adhesive layer, wherein the first adhesive layer is connected to the display screen and the first metal layer, and the second adhesive layer is connected to the first metal layer and the spacing layer;

the second connection layer includes: second metal level, third glue film and fourth glue film, the third glue film connect in the spacer layer with the second metal level, the fourth glue film connect in the second metal level with piezoelectric transducer.

6. The ultrasonic fingerprint identification device according to claim 5, wherein the absorption rate of the first adhesive layer to visible light is greater than 70%, and/or the thickness of the first adhesive layer is between 3 μm and 30 μm.

7. The ultrasonic fingerprint identification device according to claim 5, wherein the thickness of the fourth glue layer is between 3 μm and 30 μm.

8. The ultrasonic fingerprint recognition device according to any one of claims 1 to 6, wherein the circuit board is a flexible circuit board, the flexible circuit board comprising: the ultrasonic fingerprint sensor comprises a circuit layer and a reinforcing layer arranged below the circuit layer, wherein a window is formed in the circuit layer, and the ultrasonic fingerprint sensor chip is arranged in the window and fixed on the reinforcing layer;

the chip bonding pad of the ultrasonic fingerprint sensor chip is located in the edge area of the silicon substrate, and the circuit board bonding pad of the flexible circuit board is located in the edge area of the window in the circuit layer.

9. The ultrasonic fingerprint identification device according to claim 8, wherein the connection spacer layer covers the window, and the connection spacer layer is connected between the piezoelectric transducer of the ultrasonic fingerprint sensor chip and the display screen and between the circuit layer and the display screen.

10. The ultrasonic fingerprint identification device according to claim 9, wherein foam is disposed in the circuit layer in a peripheral region of the window, and the connection spacer layer is connected between the circuit layer and the display screen through the foam.

11. The ultrasonic fingerprint identification device according to any one of claims 1 to 6, wherein a receiving area facing the lead is formed in the connection spacer layer, and the receiving area provides a receiving space under the display screen for the lead.

12. The ultrasonic fingerprint identification device according to claim 11, wherein the first connection layer in the connection spacer layer is a continuous structure, and the spacer layer in the connection spacer layer and the second connection layer are formed with through holes to form the accommodation region in the connection spacer layer;

the first connecting layer is arranged above the lead in a covering mode.

13. The ultrasonic fingerprint identification device according to claim 12, wherein the first connection layer, the spacing layer and the second connection layer in the connection spacing layer are each formed with a through hole to form the accommodation region in the connection spacing layer;

and the lead is covered with black protective glue.

14. The ultrasonic fingerprint identification device according to any one of claims 1 to 6, wherein the edge of at least part of the laminated layers in the connection spacer layer exceeds the edge of the circuit board;

the ultrasonic fingerprint recognition device further comprises: the fixing glue is arranged in the edge area of at least part of the laminated layers in the connecting spacing layer, and surrounds the circuit board and wraps at least part of the side face of the circuit board.

15. The ultrasonic fingerprint identification device of claim 14, wherein the edges of at least some of the laminations in the connecting spacer layer extend more than 0.5mm beyond the edges of the circuit board.

16. The ultrasonic fingerprint identification device of claim 14, wherein an edge of at least a first connection layer in the connection spacer layer extends beyond an edge of the circuit board.

17. The ultrasonic fingerprint recognition device of claim 14, further comprising: and the shading glue is arranged on the display screen and surrounds the periphery of the connecting spacing layer.

18. The ultrasonic fingerprint identification device according to claim 17, wherein the width of the light shielding glue is greater than or equal to 0.1mm, and/or the absorption rate of the light shielding glue to visible light is greater than or equal to 70%.

19. The ultrasonic fingerprint identification device according to any one of claims 1 to 6, wherein the edge of the connection spacing layer is flush with the edge of the circuit board or the edge of the connection spacing layer is recessed within 0.5mm compared to the edge of the circuit board;

the ultrasonic fingerprint recognition device further comprises: the fixing glue is arranged on the display screen, surrounds the connection spacing layer and the circuit board and coats at least part of side faces of the connection spacing layer and the circuit board.

20. The ultrasonic fingerprint identification device of claim 19, wherein the width of the fixing glue is greater than or equal to 0.1mm.

21. The ultrasonic fingerprint recognition device according to any one of claims 1 to 6, wherein the range of the thickness of the ultrasonic fingerprint recognition device is less than or equal to 500 μm.

22. The ultrasonic fingerprint identification device according to any one of claims 1 to 6, wherein the display screen is an unfolded screen, the lowest layer of the unfolded screen is a buffer layer, a buffer layer window is formed in the buffer layer, and the ultrasonic fingerprint identification device is disposed in the buffer layer window and attached to the substrate layer above the buffer layer in the unfolded screen through the connection spacer.

23. The ultrasonic fingerprint identification device of claim 22, wherein the edge of the cushioning layer window extends more than 0.1mm beyond the edge of the connecting spacer layer.

24. The ultrasonic fingerprint identification device according to any one of claims 1 to 6, wherein the display screen is a folding screen, the lowest layer of the folding screen is a supporting layer, and the ultrasonic fingerprint identification device is attached to the supporting layer through the connecting spacing layer.

25. An electronic device, comprising: a display screen and the ultrasonic fingerprint recognition device according to any one of claims 1 to 21;

the display screen is used for providing a pressing interface of a finger and receiving the pressing of the finger;

the ultrasonic fingerprint identification device is arranged below the display screen and used for identifying the fingerprint of the finger pressed on the display screen.

26. The electronic device of claim 25, wherein the display screen is an unfolded screen, a lowest layer of the unfolded screen is a buffer layer, a buffer layer window is formed in the buffer layer, and the ultrasonic fingerprint identification device is disposed in the buffer layer window and attached to a substrate layer above the buffer layer in the unfolded screen.

27. The electronic device of claim 25, wherein the display screen is a foldable screen, a bottom layer of the foldable screen is a supporting layer, and the ultrasonic fingerprint recognition device is attached to the supporting layer.