Ultrasonic fingerprint identification module

Abstract

An ultrasonic fingerprint identification module includes a circuit substrate, a piezoelectric layer, an electrode layer, a protective layer, and a plurality of gas guide holes. The circuit substrate includes an effective area; the piezoelectric layer is arranged above the circuit substrate; the electrode layer is stacked above the piezoelectric layer; the protective layer is stacked above the electrode layer; each gas guide hole is a gas exhaust structure penetrating through the electrode layer and the protective layer, and each gas guide hole is located outside the orthographic projection range of the effective area. The ultrasonic fingerprint identification module provided by the present application can solve the problem of destroying the structural integrity due to the generation of bubbles during heating, thereby affecting the yield of the product.

Description

TECHNICAL FIELD

[0001] The present application relates to an ultrasonic fingerprint identification module, in particular to an ultrasonic fingerprint identification module capable of removing the influence of air bubbles between layers. BACKGROUND

[0002] With the popularity of smart phones and tablet computers and other touch panels, people's expectations for touch panels have gradually increased, and one of the main development trends is to pursue larger touch screens in the same size and design. Therefore, unlike the past, the physical button for fingerprint identification is set under the screen to obtain a larger touch screen, which has become the mainstream design direction of touch panels.

[0003] In the fingerprint identification module, the fingerprint identification technology used can be mainly divided into capacitive fingerprint identification technology, resistive fingerprint identification technology, optical fingerprint identification technology and ultrasonic fingerprint identification technology. The fingerprint identification module using ultrasonic fingerprint identification technology, hereinafter referred to as ultrasonic fingerprint identification module, emits ultrasonic waves, which are reflected by the ridges and valleys on the fingerprint, and then converted into electronic signals through the piezoelectric effect to obtain fingerprint information, thereby performing subsequent fingerprint identification. Since ultrasonic waves have penetrating power, they are less affected by dirt or sweat on the finger or fingerprint recognition area compared to other fingerprint identification technologies, and can perform high-precision and fast fingerprint identification. Ultrasonic fingerprint identification technology is one of the focuses of fingerprint identification technology development in recent years, and its commercial application range is also gradually expanding.

[0004] However, there are still many problems to be overcome in ultrasonic fingerprint identification technology, one of which is that in the structure of the ultrasonic fingerprint identification module, a piezoelectric layer, an electrode layer and a protective layer are generally sequentially stacked above a thin film transistor. Screen printing is used to prepare the electrode layer and the protective layer. In order to achieve the above-mentioned effect, the electrode layer and the protective layer must both achieve a target thickness of at least 20 microns (μm). Therefore, the electrode layer and the protective layer must be screen printed multiple times to achieve the target thickness. However, when screen printing is performed multiple times, air may be trapped between different layers when they are stacked. These gases will form bubbles when heated due to the increase in temperature, and in the case where the bubbles cannot be removed, the different layers will experience irreversible spatial deformation due to continuous bubble extrusion, thereby affecting the product yield of the touch panel using the ultrasonic fingerprint identification module. SUMMARY

[0005] One object of the present application is to solve the problem that when preparing a touch panel using an ultrasonic fingerprint identification module, air bubbles are generated between the layers of the ultrasonic fingerprint identification module during heating, affecting the structural integrity of the ultrasonic fingerprint identification module and thereby affecting the product yield.

[0006] Based on an object of the present application, an ultrasonic fingerprint recognition module is provided, comprising a circuit substrate, a piezoelectric layer, an electrode layer, a protective layer, and a plurality of air guiding holes, wherein the circuit substrate comprises an effective area, the piezoelectric layer is stacked above the circuit substrate, the electrode layer is stacked above the piezoelectric layer, the protective layer is stacked above the electrode layer, each air guiding hole is an air exhaust structure penetrating through the electrode layer and the protective layer, and each air guiding hole is located outside the orthographic projection range of the effective area.

[0007] In an embodiment of the present application, the electrode layer is formed by stacking a plurality of conductive layers.

[0008] In a preferred embodiment of the present application, the electrode layer is formed by stacking two to four conductive layers.

[0009] In an embodiment of the present application, the protective layer is formed by stacking a plurality of ink layers.

[0010] In a preferred embodiment of the present application, the protective layer is formed by stacking two to four ink layers.

[0011] In an embodiment of the present application, the orthographic projection area of the protective layer on the circuit substrate and the orthographic projection area of the electrode layer on the circuit substrate are both greater than the orthographic projection area of the effective area on the circuit substrate, and the orthographic projection area of the protective layer on the circuit substrate is greater than the orthographic projection area of the electrode layer on the circuit substrate.

[0012] In an embodiment of the present application, the electrode layer is formed by stacking a plurality of conductive layers, the protective layer is formed by stacking a plurality of ink layers, each conductive layer and each ink layer is respectively provided with a plurality of air holes, each of the air holes of adjacent two layers is arranged in alignment or partially overlapped, and is in communication with each other to form a plurality of air guiding holes.

[0013] In an embodiment of the present application, the three-dimensional shape of each air hole is a corner cylinder, a circular cylinder, an elliptical cylinder, a parallelepiped, a pyramid frustum, or a double-cone frustum. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 It is a top view schematic diagram of an embodiment of the ultrasonic fingerprint recognition module of the present application.

[0015] Figure 2 It is a longitudinal sectional view at the B-B section line of Figure 1 , wherein the air guiding hole is shown as a rectangular air exhaust structure penetrating through the electrode layer and the protective layer.

[0016] Figure 3 It is a longitudinal sectional view at the B-B section line of Figure 1A longitudinal cross-sectional diagram at the BB section line shows that the air guide hole is a trapezoidal exhaust structure that penetrates the electrode layer and the protective layer and is narrow at the top and wide at the bottom.

[0017] Figure 4 for Figure 1 A longitudinal cross-sectional view at the BB section line, in which the air guide hole presents a trapezoidal exhaust structure that penetrates the electrode layer and the protective layer and is wider at the top and narrower at the bottom.

[0018] Figure 5 for Figure 1 The schematic diagram of the longitudinal section at the BB section line shows that the first vent, second vent, third vent, fourth vent, fifth vent, and sixth vent are partially overlapping.

[0019] Figure 6 This is a top view of an embodiment of the ultrasonic fingerprint recognition module of the present invention, wherein each air vent is arranged around the effective area.

[0020] Figure 7 This is a top view schematic diagram of an embodiment of the ultrasonic fingerprint recognition module of the present invention, wherein the air vent is a circular exhaust structure that penetrates the electrode layer and the protective layer.

[0021] Figure 8 This is a top view schematic diagram of the relevant positions of the ultrasonic fingerprint recognition module of the present invention, in which the effective area and the electrode layer are projected onto the top surface of the protective layer.

[0022] Figure 9 This is a longitudinal cross-sectional view taken with a scanning electron microscope after the control group underwent environmental testing.

[0023] Figure 10 This is a longitudinal cross-sectional image taken with a scanning electron microscope after the operation team underwent environmental testing.

[0024] The attached figures are labeled as follows:

[0025] 1: Ultrasonic fingerprint recognition module H5: Fifth spacing

[0026] 2: Circuit board H6: Sixth spacing

[0027] 20: Effective area H7: Seventh spacing

[0028] 3: Piezoelectric layer H8: Eighth spacing

[0029] 4: Electrode layer

[0030] 40: First conductive layer

[0031] 400: First vent

[0032] 42: second conductive layer

[0033] 420: second vent hole

[0034] 44: third conductive layer

[0035] 440: third vent hole

[0036] 5: protective layer

[0037] 50: first ink layer

[0038] 500: fourth vent hole

[0039] 52: second ink layer

[0040] 520: fifth vent hole

[0041] 54: third ink layer

[0042] 540: sixth vent hole

[0043] 6: air vent hole

[0044] B-B: section line

[0045] D1: lateral interval

[0046] D2: longitudinal interval

[0047] H1: first interval

[0048] H2: second interval

[0049] H3: third interval

[0050] H4: fourth interval

[0051] V: void DETAILED DESCRIPTION

[0052] In order to make the person skilled in the art of the present application easy to understand the content of the present application, the present application is further explained below in combination with the embodiments and the drawings, each embodiment is only used to illustrate the technical features of the present application, and the mentioned content is not a limitation of the present application.

[0053] In the description of the present application, it should be noted that the terms "upper", "lower", "left", "right", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or components referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, "first", "second", "third", "fourth", "fifth", "sixth", "seventh", "eighth" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0054] "one embodiment" described throughout the specification means that the specific features, structures or characteristics described in connection with the embodiment are included in at least one embodiment. Therefore, "one embodiment" described at various positions throughout the specification does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics can be combined in any way in one or more embodiments.

[0055] Please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 , the ultrasonic fingerprint identification module 1 includes a circuit substrate 2, a piezoelectric layer 3, an electrode layer 4, a protective layer 5 and a plurality of gas guide holes 6. The piezoelectric layer 3 is stacked above the circuit substrate 2, the electrode layer 4 is stacked above the piezoelectric layer 3, and the protective layer 5 is stacked above the electrode layer 4. The effective area 20 for fingerprint identification is included on the circuit substrate 2. The electrode layer 4 is formed by stacking a plurality of conductive layers. The protective layer 5 is formed by stacking a plurality of ink layers. Each conductive layer and each ink layer is respectively provided with a plurality of air holes, and each of the plurality of air holes of the adjacent two layers is aligned or partially overlapped, and communicates with each other to form the plurality of gas guide holes 6. The area of the protective layer 5 in the orthographic projection on the circuit substrate 2 and the area of the electrode layer 4 in the orthographic projection on the circuit substrate 2 are both greater than the area of the effective area 20 in the orthographic projection on the circuit substrate 2. The area of the protective layer 5 in the orthographic projection on the circuit substrate 2 is greater than the area of the electrode layer 4 in the orthographic projection on the circuit substrate 2. The three-dimensional shape of each air hole can be a corner cylinder, a circular cylinder, an elliptical cylinder, a parallelepiped, a pyramid, or a double cone, etc. Each gas guide hole 6 is a gas exhaust structure penetrating through the electrode layer 4 and the protective layer 5, and the plurality of gas guide holes 6 are located outside the orthographic projection range of the effective area 20. By arranging the plurality of gas guide holes 6 outside the orthographic projection range of the effective area 20, the plurality of gas guide holes 6 can avoid affecting the ultrasonic fingerprint identification function of the ultrasonic fingerprint identification module 1 in the effective area 20. The "orthographic projection range of the effective area 20" refers to the area of the effective area 20 projected onto the electrode layer 4 and the protective layer 5 in the state of viewing the ultrasonic fingerprint identification module 1 from above. As shown in Figure 1As shown, in an embodiment of the present application, the diameters of the gas guide holes 6 can be the same or have different diameters and / or shapes.

[0056] In the ultrasonic fingerprint identification module 1, when the piezoelectric layer 3 receives electric energy, it will convert the electric energy into mechanical energy through the piezoelectric effect, so that the piezoelectric layer 3 deforms. Through this characteristic, by providing alternating current of a specific frequency, the piezoelectric layer 3 generates waves of the corresponding frequency. In addition, the piezoelectric layer 3 can also deform by external force to generate corresponding electronic signals through the piezoelectric effect. Therefore, the piezoelectric layer 3 can have the functions of emitting ultrasonic waves and receiving ultrasonic waves and converting them into electronic signals. First, the piezoelectric layer 3 is powered to generate ultrasonic waves, and then the piezoelectric layer 3 is powered off and converted into a detection mode. After the ultrasonic waves collide with the fingerprint, they will be reflected. The reflected ultrasonic waves are received by the piezoelectric layer 3, causing the piezoelectric layer 3 to deform and generate corresponding electronic signals, which can be transmitted to the circuit substrate 2 for analysis. The electrode layer 4 is used for transmitting electronic signals. The protective layer 5 is used to shield the electrode layer 4.

[0057] Please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 , in an embodiment of the present application, the electrode layer 4 is formed by stacking three conductive layers, including a first conductive layer 40, a second conductive layer 42 and a third conductive layer 44, wherein the first conductive layer 40 is stacked above the piezoelectric layer 3, the second conductive layer 42 is stacked above the first conductive layer 40, and the third conductive layer 44 is stacked above the second conductive layer 42. The protective layer 5 is formed by stacking three ink layers, including a first ink layer 50, a second ink layer 52 and a third ink layer 54, wherein the first ink layer 50 is stacked above the third conductive layer 44, the second ink layer 52 is stacked above the first ink layer 50, and the third ink layer 54 is stacked above the second ink layer 52. Each gas guide hole 6 is arranged in alignment or partially overlapping with each other and in communication with each other, wherein the first gas guide hole 400 is arranged through the first conductive layer 40, the second gas guide hole 420 is arranged through the second conductive layer 42, the third gas guide hole 440 is arranged through the third conductive layer 44, the fourth gas guide hole 500 is arranged through the first ink layer 50, the fifth gas guide hole 520 is arranged through the second ink layer 52, and the sixth gas guide hole 540 is arranged through the third ink layer 54.

[0058] In an embodiment of the present application, the circuit substrate 2 is a thin film transistor, and the thickness of the thin film transistor is 90-200 microns; the piezoelectric layer 3 is composed of any one of polyvinylidene fluoride (PVDF), Poly-L-Lactic Acid (PLLA), polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE), polyvinylidene fluoride-tetrafluoroethylene, lead zirconate titanate (PZT), or a combination thereof; the electrode layer 4 is composed of any one of aluminum (Al), silver (Ag), gold (Au), cobalt (Co), chromium (Cr), copper (Cu), indium (In), manganese (Mn), molybdenum (Mo), nickel (Ni), neodymium (Nd), palladium (Pd), platinum (Pt), titanium (Ti), tungsten (W), zinc (Zn), iron (Fe), indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), zinc oxide (ZnO), aluminum zinc oxide (AZO), cadmium tin oxide (CTO), titanium oxide (TiO), poly(3,4-ethylenedioxythiophene) (PEDOT), graphene, carbon nanotube, or a combination thereof; and the protective layer 5 is composed of a shielding ink.

[0059] Referring to Figure 2 In an embodiment of the present application, the first vent hole 400, the second vent hole 420, the third vent hole 440, the fourth vent hole 500, the fifth vent hole 520, and the sixth vent hole 540 in each gas guide hole 6 are arranged in an overlapping manner. The first vent hole 400, the second vent hole 420, the third vent hole 440, the fourth vent hole 500, the fifth vent hole 520, and the sixth vent hole 540 are all cuboids in a rectangular prism, and have the same size. Therefore, as viewed from the longitudinal cross-sectional view, the gas guide hole 6 appears as a rectangular exhaust structure that penetrates the electrode layer 4 and the protective layer 5.

[0060] Referring to Figure 3, in an embodiment of the present application, the first vent hole 400, the second vent hole 420, the third vent hole 440, the fourth vent hole 500, the fifth vent hole 520 and the sixth vent hole 540 in each gas guiding hole 6 are arranged in an overlapping manner. The first vent hole 400, the second vent hole 420, the third vent hole 440, the fourth vent hole 500, the fifth vent hole 520 and the sixth vent hole 540 are all in the shape of a four-pyramidal frustum with a narrow upper plane and a wide lower plane, and the planes of the vent holes in adjacent layers are of the same size. Therefore, as viewed from the longitudinal cross-sectional view, the gas guiding hole 6 is in the shape of a trapezoidal exhaust structure penetrating through the electrode layer 4 and the protective layer 5, with a narrow upper edge and a wide lower edge. Compared with the structure in which the shapes and sizes of the vent holes are all the same, the gas guiding hole 6 has a larger contact area with each layer, so that the gas between the layers can be more effectively exhausted to the outside. Figure 2 , in an embodiment of the present application, the first vent hole 400, the second vent hole 420, the third vent hole 440, the fourth vent hole 500, the fifth vent hole 520 and the sixth vent hole 540 in each gas guiding hole 6 are arranged in an overlapping manner. The first vent hole 400, the second vent hole 420, the third vent hole 440, the fourth vent hole 500, the fifth vent hole 520 and the sixth vent hole 540 are all in the shape of a four-pyramidal frustum with a narrow upper plane and a wide lower plane, and the planes of the vent holes in adjacent layers are of the same size. Therefore, as viewed from the longitudinal cross-sectional view, the gas guiding hole 6 is in the shape of a trapezoidal exhaust structure penetrating through the electrode layer 4 and the protective layer 5, with a narrow upper edge and a wide lower edge. Compared with the structure in which the shapes and sizes of the vent holes are all the same, the gas guiding hole 6 has a larger contact area with each layer, so that the gas between the layers can be more effectively exhausted to the outside.

[0061] Please refer to Figure 4 , in another embodiment of the present application, the first vent hole 400, the second vent hole 420, the third vent hole 440, the fourth vent hole 500, the fifth vent hole 520 and the sixth vent hole 540 in each gas guiding hole 6 are arranged in an overlapping manner. The first vent hole 400, the second vent hole 420, the third vent hole 440, the fourth vent hole 500, the fifth vent hole 520 and the sixth vent hole 540 are all in the shape of a four-pyramidal frustum with a wide upper plane and a narrow lower plane, and the planes of the vent holes in adjacent layers are of the same size. Therefore, as viewed from the longitudinal cross-sectional view, the gas guiding hole 6 is in the shape of a trapezoidal exhaust structure penetrating through the electrode layer 4 and the protective layer 5, with a wide upper edge and a narrow lower edge. Compared with the structure in which the shapes and sizes of the vent holes are all the same, the gas guiding hole 6 has a larger contact area with each layer, so that the gas between the layers can be more effectively exhausted to the outside. Figure 2 , in another embodiment of the present application, the first vent hole 400, the second vent hole 420, the third vent hole 440, the fourth vent hole 500, the fifth vent hole 520 and the sixth vent hole 540 in each gas guiding hole 6 are arranged in an overlapping manner. The first vent hole 400, the second vent hole 420, the third vent hole 440, the fourth vent hole 500, the fifth vent hole 520 and the sixth vent hole 540 are all in the shape of a four-pyramidal frustum with a wide upper plane and a narrow lower plane, and the planes of the vent holes in adjacent layers are of the same size. Therefore, as viewed from the longitudinal cross-sectional view, the gas guiding hole 6 is in the shape of a trapezoidal exhaust structure penetrating through the electrode layer 4 and the protective layer 5, with a wide upper edge and a narrow lower edge. Compared with the structure in which the shapes and sizes of the vent holes are all the same, the gas guiding hole 6 has a larger contact area with each layer, so that the gas between the layers can be more effectively exhausted to the outside.

[0062] Please refer to Figure 5 , in an embodiment of the present application, the first vent hole 400, the second vent hole 420, the third vent hole 440, the fourth vent hole 500, the fifth vent hole 520 and the sixth vent hole 540 in each gas guiding hole 6 are arranged in an overlapping manner. The first vent hole 400, the second vent hole 420, the third vent hole 440, the fourth vent hole 500, the fifth vent hole 520 and the sixth vent hole 540 are all in the shape of a four-pyramidal frustum with a narrow upper plane and a wide lower plane, and the planes of the vent holes in adjacent layers are of the same size. Therefore, as viewed from the longitudinal cross-sectional view, the gas guiding hole 6 is in the shape of a trapezoidal exhaust structure penetrating through the electrode layer 4 and the protective layer 5, with a narrow upper edge and a wide lower edge. Compared with the structure in which the shapes and sizes of the vent holes are all the same, the gas guiding hole 6 has a larger contact area with each layer, so that the gas between the layers can be more effectively exhausted to the outside.

[0063] Please refer to Figure 6In an embodiment of the present application, each gas guiding hole 6 is located outside the orthographic projection range of the effective area 20, and a plurality of gas guiding holes 6 are arranged around the periphery of the effective area 20, thereby increasing the contact area between the gas guiding holes 6 and the layers, so that the gas between the layers can be more effectively discharged to the outside. In this embodiment, the three-dimensional shape of each gas guiding hole 6 is a cuboid in a corner cylinder, and one side edge of the gas guiding hole 6 further extends to the edge of the protective layer 5, so that the edge of the electrode layer 4 and the edge of the protective layer 5 present a comb-like structure. Therefore, each gas guiding hole 6 can not only remove the gas trapped between the layers of the overlapping parts of the electrode layer 4 and the protective layer 5, but also further remove the gas trapped between the layers of the protective layer 5 outside the orthographic projection range of the effective area 20 and not overlapping with the orthographic projection range of the electrode layer 4.

[0064] Please refer to Figure 7 In an embodiment of the present application, the first air hole 400, the second air hole 420, the third air hole 440, the fourth air hole 500, the fifth air hole 520, and the sixth air hole 540 in each gas guiding hole 6 are arranged in an overlapping manner. The three-dimensional shape of each of the first air hole 400, the second air hole 420, the third air hole 440, the fourth air hole 500, the fifth air hole 520, and the sixth air hole 540 is a cylinder with a diameter of 0.5 mm, and they are arranged at equal distances. The horizontal distance D1 and the vertical distance D2 between two adjacent air holes in the same layer are both 1 mm. The horizontal distance D1 represents the length of the line connecting the center points of two horizontally adjacent air holes, and the vertical distance D2 represents the length of the line connecting the center points of two vertically adjacent air holes.

[0065] The gas between the piezoelectric layer 3 and the first conductive layer 40, the gas between the first conductive layer 40 and the second conductive layer 42, the gas between the second conductive layer 42 and the third conductive layer 44, the gas between the third conductive layer 44 and the first ink layer 50, the gas between the first ink layer 50 and the second ink layer 52, and the gas between the second ink layer 52 and the third ink layer 54 will all be removed during the heating stage. Due to the expansion of the gas volume caused by the heating of the gas between the layers, bubbles are formed between the layers. Since the air pressure of the bubbles formed between the layers is greater than the air pressure at the location of each gas guiding hole 6, the bubbles will move to the gas guiding hole 6 with relatively small air pressure. Finally, the bubbles will be guided out of the layers to the outside through each gas guiding hole 6, thereby solving the problem that during the preparation of a touch panel using ultrasonic fingerprint recognition technology, bubbles are generated between the layers during heating, which affects the structural integrity of the product and thus affects the yield of the product.

[0066] Please refer to Figure 8 In an embodiment of the present application, the effective area 20 and the electrode layer 4 are orthographically projected onto the top surface of the protective layer 5, and the direction is defined from the perspective of an observer. When the observer looks horizontally Figure 8The left side of the projection surface of the electrode layer 4 and the left side edge of the projection surface of the effective area 20 are referred to as the "first interval H1", the upper side edge of the projection surface of the electrode layer 4 and the upper side edge of the projection surface of the effective area 20 are referred to as the "second interval H2", the right side edge of the projection surface of the electrode layer 4 and the right side edge of the projection surface of the effective area 20 are referred to as the "third interval H3", the lower side edge of the projection surface of the electrode layer 4 and the lower side edge of the projection surface of the effective area 20 are referred to as the "fourth interval H4", the left side edge of the protective layer 5 and the left side edge of the projection surface of the electrode layer 4 are referred to as the "fifth interval H5", the upper side edge of the protective layer 5 and the upper side edge of the projection surface of the electrode layer 4 are referred to as the "sixth interval H6", the right side edge of the protective layer 5 and the right side edge of the projection surface of the electrode layer 4 are referred to as the "seventh interval H7", and the lower side edge of the protective layer 5 and the lower side edge of the projection surface of the electrode layer 4 are referred to as the "eighth interval H8". The first interval H1, the second interval H2, the third interval H3, and the fourth interval H4 are collectively referred to as the "first interval group", and the fifth interval H5, the sixth interval H6, the seventh interval H7, and the eighth interval H8 are collectively referred to as the "second interval group". The lengths of the intervals are shown in Table 1 below. The lengths of the first interval H1, the second interval H2, the third interval H3, and the fourth interval H4 are all 0.6 mm, the lengths of the fifth interval H5 and the seventh interval H7 are both 2.11 mm, the length of the sixth interval H6 is 3.09 mm, and the length of the eighth interval H8 is 0.2 mm. The screen printing size tolerance for screen printing the electrode layer 4 and the protective layer 5 is 0.05 mm. The printing size tolerance for screen printing is 0.25 mm. The calculation formula for the length of the gas guiding hole 6 in each direction on the electrode layer 4 is: the interval corresponding to the direction in the first interval group minus the screen printing size tolerance and the printing size tolerance. The calculated value represents the length of the electrode layer 4 extending from the edge of the electrode layer 4 in the corresponding direction to the opposite direction. For example, the length of the gas guiding hole 6 on the left side of the electrode layer 4 is: the first interval H1 minus the screen printing size tolerance and the printing size tolerance, which is "0.6-0.05-0.25=0.3". Therefore, the calculation shows that the length of the gas guiding hole 6 on the left side of the electrode layer 4 is 0.3 mm, which represents the length of the electrode layer 4 extending from the left edge of the electrode layer 4 to the right side.3mm, all of which can be used to set the air holes 6, and other similar, the electrode layer 4 in each direction can be used to set the length of the air hole 6 as shown in Table 2 below; wherein the calculation formula of the length of the protective layer 5 in each direction can be used to set the air hole 6 is: the distance in the second distance group corresponding to the direction plus the length of the electrode layer 4 in the corresponding direction which can be used to set the air hole 6, the calculated value represents the length of the protective layer 5 extending from the edge of the protective layer 5 in the corresponding direction to the opposite direction of the corresponding direction, for example, the length of the left side of the protective layer 5 which can be used to set the air hole 6 is the fifth distance H5 plus the length of the left side of the electrode layer 4 which can be used to set the air hole 6, the mathematical formula is "2.11+0.3=2.41", which means that the area within 2.41mm extending from the left edge of the protective layer 5 to the right side of the protective layer 5 can be used to set the air hole 6, and other similar, the length of the protective layer 5 in each direction which can be used to set the air hole 6 is shown in Table 3 below. The results of this embodiment show that in the ultrasonic fingerprint identification module 1, even considering the influence of screen size tolerance and printing size tolerance, the ultrasonic fingerprint identification module 1 still includes an area which can be used to set the air hole 6, and the area which can be used to set the air hole 6 is located outside the range of the effective area 20 projection, which shows that the air hole 6 described in the present application can indeed be set in the ultrasonic fingerprint identification module 1.

[0067] Table 1: Distance length of each distance

[0068]

[0069] Table 2: Length of the electrode layer 4 in each direction which can be used to set the air hole 6

[0070]

[0071] Table 3: Length of the protective layer 5 in each direction which can be used to set the air hole 6

[0072]

[0073] Please refer to Figure 9 and Figure 10, in an embodiment of the present application, the influence of setting the plurality of gas guide holes 6 is compared, so as to be divided into a group without setting the gas guide holes 6, and a group with setting the plurality of gas guide holes 6, which will be referred to as a control group below, and a group with setting the plurality of gas guide holes 6, which will be referred to as an operation group. Both the control group and the operation group are provided with the piezoelectric layer 3 above the circuit substrate 2, and the piezoelectric layer 3 is sequentially stacked with three screen printing of conductive silver paste to form the electrode layer 4, and then sequentially stacked with three screen printing of shielding ink to form the protective layer 5, but when screen printing is performed on the operation group, the printing of each conductive layer and each ink layer is simultaneously completed with the setting of the plurality of gas guide holes. Both the control group and the operation group are subjected to high temperature and high humidity environmental testing, wherein the specific conditions of the environmental testing are that each group is exposed to an environment with a temperature of 85 degrees Celsius and a relative humidity of 85% for 240 hours, and after the environmental testing is completed, a longitudinal cross-sectional view of each group is taken by a scanning electron microscope to observe whether there is a gap V. In Figure 9 the control group, it is observed that the protective layer 5 of the control group has a gap V after the environmental testing is completed, which represents that during the environmental testing of the control group, the gas trapped between the layers becomes bubbles due to heating, and the gap V in the protective layer 5 appears due to the continuous extrusion of the bubbles, which affects the integrity of the stacked structure. In contrast, in Figure 10 the operation group, both the electrode layer 4 and the protective layer 5 are complete stacking, and there is no gap V in the protective layer 5 and the electrode layer 4. The experimental results of the present embodiment prove that the plurality of gas guide holes 6 set in the present application can indeed help to guide the interlayer gas out to the outside, and maintain the integrity of the stacked structure.

[0074] In summary, the present application sets a plurality of gas guide holes outside the range of the orthographic projection of the effective area of the touch panel, so as to solve the problem that when a touch panel using an ultrasonic fingerprint recognition module is generally prepared, bubbles are generated between the layers of the ultrasonic fingerprint recognition module during heating, which affects the structural integrity of the ultrasonic fingerprint recognition module, and further affects the product yield.

Claims

1. An ultrasonic fingerprint identification module, characterized in that, The application relates to a piezoelectric layer, which comprises: a circuit substrate comprising an active area; a piezoelectric layer stacked above the circuit substrate; an electrode layer stacked above the piezoelectric layer; a protective layer stacked above the electrode layer; and a plurality of air guide holes, each of the air guide holes being an air exhaust structure penetrating the electrode layer and the protective layer, and each of the air guide holes being located outside the range of the orthographic projection of the active area, wherein the three-dimensional shape of each of the air guide holes is a cuboid in a corner column, and one side edge of each of the air guide holes further extends to the edge of the protective layer, so that the edges of the electrode layer and the protective layer present a comb-shaped structure. The electrode layer is formed by stacking a plurality of conductive layers. 2.The ultrasonic fingerprint identification module of claim 1, wherein, The protective layer is formed by stacking a plurality of ink layers. 3.The ultrasonic fingerprint identification module of claim 1, wherein, The electrode layer is formed by stacking two to four conductive layers. 4.The ultrasonic fingerprint identification module of claim 2, wherein, The protective layer is formed by stacking two to four ink layers. 5.The ultrasonic fingerprint identification module of claim 3, wherein, The orthographic projection area of the protective layer on the circuit substrate and the orthographic projection area of the electrode layer on the circuit substrate are both greater than the orthographic projection area of the active area on the circuit substrate, and the orthographic projection area of the protective layer on the circuit substrate is greater than the orthographic projection area of the electrode layer on the circuit substrate. 6.The ultrasonic fingerprint identification module of claim 1, wherein, The electrode layer is formed by stacking a plurality of conductive layers, wherein the protective layer is formed by stacking a plurality of ink layers, wherein each of the conductive layers and each of the ink layers is respectively provided with a plurality of air holes, and each of the air holes of two adjacent layers is arranged in alignment or partially overlaps and communicates with each other to form the plurality of air guide holes. 7.The ultrasonic fingerprint identification module of claim 1, wherein, The electrode layer is formed by stacking two to four conductive layers. 8.The ultrasonic fingerprint identification module of claim 7, wherein, The protective layer is formed by stacking two to four ink layers. 9.The ultrasonic fingerprint identification module of claim 7, wherein, ​

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