Structure for improving performance of ultrasonic fingerprint recognition module

Abstract

The application provides a structure for improving the performance of an ultrasonic fingerprint recognition module, comprising a substrate; an ultrasonic emission layer disposed above the substrate; a coating layer disposed between the substrate and the ultrasonic emission layer; a first silver layer disposed above the ultrasonic emission layer; a second silver layer disposed above the first silver layer; and a first insulating layer disposed above the second silver layer. The second silver layer is formed by silver particles with a particle size less than or equal to 1.6 μm and a circular shape. By increasing the particle size, the second silver layer has a finer surface and improved uniformity, thereby improving the accuracy of fingerprint recognition.

Description

Technical Field

[0001] This application relates to the structure of an ultrasonic fingerprint recognition module, and more particularly to a structure for improving the performance of an ultrasonic fingerprint recognition module. Background Technology

[0002] Please see Figure 1 A typical ultrasonic fingerprint recognition module consists of an epoxy layer A1, an electrode layer A2, a piezoelectric thin film layer A3, a polymer layer A4, and a driving substrate A5 stacked from top to bottom. When a fingerprint is pressed onto the epoxy layer A1, the electrode layer A2, the piezoelectric thin film layer A3, the polymer layer A4, and the driving substrate A5 work together to press the fingerprint onto the ultrasonic fingerprint recognition module. The electrode layer A2 (i.e., the transmitting end) emits ultrasonic waves, which collide with the fingerprint and are reflected onto the piezoelectric thin film layer A3 (i.e., the receiving end). The peak and valley distribution on the fingerprint is obtained through the path difference of the back-and-forth propagation. The fingerprint is then verified by comparing local features on the fingerprint (such as fingerprint ridge endpoints, fingerprint ridge bifurcation points, or short fingerprint ridges).

[0003] Generally, the electrode layer A2 requires high surface uniformity due to the high thickness uniformity requirement of the ultrasonic fingerprint recognition module. In addition, when multiple metal layers are provided in the electrode layer A2 and a target thickness is reached, the quality of the ultrasonic signal propagating in the target thickness can also be optimized.

[0004] However, uneven uniformity or failure of the electrode layer A2 to reach the target thickness will affect the accuracy of fingerprint recognition. Therefore, how to overcome the problems encountered by the electrode layer A2 in practice, improve the accuracy of fingerprint recognition, and improve the surface roughness are the technical difficulties to be solved. Summary of the Invention

[0005] In view of the problems of the related technologies, the purpose of this application is to improve the problem of uneven electrode layer uniformity and improve the accuracy of fingerprint recognition. Therefore, this application solves the problems of the related technologies by changing the electrode layer structure.

[0006] According to the purpose of this application, a structure for improving the performance of an ultrasonic fingerprint recognition module is provided, comprising:

[0007] substrate;

[0008] An ultrasonic emitting layer is disposed on top of the substrate;

[0009] A coating layer is disposed between the substrate and the ultrasonic emitting layer;

[0010] The first silver layer is disposed above the ultrasonic emitting layer;

[0011] A second silver layer, disposed above the first silver layer; and

[0012] A first insulating layer is disposed above a second silver layer.

[0013] In one embodiment, the first silver layer has a plurality of silver particles, the D90 of the silver particles in the first silver layer is less than or equal to 10 μm or equal to 10 μm, and the first silver layer has a thickness of 6.5 μm to 6.3 μm.

[0014] In one embodiment, the silver particles in the first silver layer are elongated silver particles.

[0015] In one embodiment, the second silver layer has a plurality of silver particles, the D90 of the silver particles in the second silver layer is less than or equal to 1.6 μm, and the second silver layer has a thickness of 5 μm to 5.3 μm.

[0016] In one embodiment, the silver particles in the second silver layer are elongated silver particles.

[0017] In one embodiment, the substrate is a thin-film transistor (TFT) substrate.

[0018] In one embodiment, the first insulating layer comprises one or more layers of insulating material.

[0019] In one embodiment, the first insulating layer has at least three layers of insulating material.

[0020] In one embodiment, the insulating material of the first insulating layer may be epoxy resin.

[0021] In one embodiment, the ultrasonic emitting layer contains a metal layer and a piezoelectric film layer.

[0022] In one embodiment, the metal layer is a silver layer having a plurality of silver particles, the D90 of the silver particles being less than or equal to 10 μm or equal to 10 μm, and the silver layer having a thickness of 6.3 μm to 6.5 μm.

[0023] In one embodiment, the silver particles in the silver layer are elongated silver particles.

[0024] In one embodiment, the piezoelectric mold layer is a copolymer, which may be polyvinylidene fluoride (PVDF).

[0025] A second silver layer is formed by using silver particles with a D90 of less than or equal to 1.6 μm and a spherical shape. By making the average particle size small, the surface of the second silver layer is made more delicate and uniform, which can improve the accuracy of fingerprint recognition. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of an ultrasonic fingerprint recognition module in related technologies.

[0027] Figure 2 This is a schematic diagram of the structure of the first ultrasonic fingerprint recognition module of this application.

[0028] Figure 3 This is a SEM diagram of the surface condition of silver particles in the first and second silver layers of the first ultrasonic fingerprint recognition module of this application.

[0029] Figure 4 This is a schematic diagram of the structure of the second type of ultrasonic fingerprint recognition module in this application.

[0030] Figure 5 This is a SEM diagram of the surface condition of silver particles in the second silver layer of the second type of ultrasonic fingerprint recognition module of this application.

[0031] Explanation of reference numerals in the attached figures:

[0032] A1: Epoxy layer

[0033] A2: Electrode layer

[0034] A3: Piezoelectric thin film layer

[0035] A4: Polymer layer

[0036] A5: Driver substrate

[0037] 1: Substrate

[0038] 2: Ultrasonic Emitting Layer

[0039] 21: Metal layer

[0040] 22: Piezoelectric film layer

[0041] 3: Coating layer

[0042] 4: First silver layer

[0043] 5: Second silver layer

[0044] 6: First insulating layer Detailed Implementation

[0045] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0046] It should be noted that when a component is referred to as being "fixed to," "set on," "pivoted to," or "actively set" to another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application's specification are for illustrative purposes only and do not represent the only possible implementation.

[0047] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the stated features. In the description of this application, "multiple" or "plural" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0048] In this application, unless otherwise expressly specified and limited, the terms "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, the terms "above," "over," and "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. The terms "above," "over," and "on top" the second feature can also mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0049] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly known to one of ordinary skill in the art to which this application belongs. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items.

[0050] Please see Figure 2 and Figure 3 As shown, Figure 2This is a schematic diagram of the structure of the first ultrasonic fingerprint recognition module of this application. Figure 2 The text indicates that the ultrasonic emitting layer 2 is bonded to the substrate 1 through the coating layer 3, and the first silver layer 4, the second silver layer 5, and the first insulating layer 6 are stacked sequentially on the ultrasonic emitting layer 2.

[0051] Figure 3 This is a SEM image of the surface condition of silver particles in the first and second silver layers of the first ultrasonic fingerprint recognition module of this application. Figure 3 The surface state of the silver layer formed by coating silver particles, wherein the D90 particle size of the silver particles is less than or equal to 10 μm and is elongated.

[0052] This application provides an ultrasonic fingerprint recognition module, including a substrate 1, an ultrasonic emitting layer 2, a coating layer 3, a first silver layer 4, a second silver layer 5, and a first insulating layer 6.

[0053] An ultrasonic emitting layer 2 is provided on the substrate 1. The substrate 1 can be a thin-film transistor (TFT) substrate. The substrate 1 is mainly used as a carrier and simultaneously drives the ultrasonic emitting layer 2 to emit ultrasonic waves through voltage. The substrate 1 can also be used for voltage signal reception.

[0054] A coating layer 3 is provided between the substrate 1 and the ultrasonic emitting layer 2. The coating layer 3 can make the ultrasonic emitting layer 2 and the substrate 1 more firmly bonded and prevent the coating from falling off. The coating layer 3 can be Primer C.

[0055] The first silver layer 4 is disposed above the ultrasonic emitting layer 2. The first silver layer 4 is formed by coating multiple silver particles and has a thickness. The D90 of the silver particles in the first silver layer 4 is less than or equal to 10 μm, that is, 90% of the silver particles in the first silver layer 4 have a particle size of less than or equal to 10 μm. This 90% particle size of the silver particles in the first silver layer 4 is only an example and is not intended to limit the application. The thickness of the first silver layer 4 is 6.3 μm to 6.5 μm. The multiple silver particles in the first silver layer 4 are elongated silver particles. The surface of the first silver layer 4 will be as shown... Figure 3 As shown.

[0056] The second silver layer 5 is disposed above the first silver layer 4. The second silver layer 5 is formed by coating multiple silver particles and has a thickness. The D90 of the silver particles in the second silver layer 5 is less than or equal to 10 μm, that is, 90% of the silver particles in the second silver layer 5 have a particle size less than or equal to 10 μm. The D90 particle size of the silver particles in the second silver layer 5 is illustrative and not a limitation thereof. The thickness of the second silver layer 5 is 6.3 μm to 6.5 μm. The multiple silver particles in the second silver layer 5 are elongated silver particles. The surface of the second silver layer 5 will also be as shown in the image. Figure 3As shown.

[0057] The first insulating layer 6 is disposed above the second silver layer 5. The first insulating layer 6 may be composed of a single layer or multiple layers of insulating material. The insulating material of the first insulating layer 6 may be epoxy resin. In one embodiment, the first insulating layer 6 is provided with at least three layers of insulating material. The first insulating layer 6 is used to protect the second silver layer 5 and the first silver layer 4.

[0058] In this embodiment, the ultrasonic emitting layer 2 is further provided with a metal layer 21 and a piezoelectric mold layer 22. The metal layer 21 is a silver layer with multiple silver particles. In other words, the multiple silver particles of the silver layer are coated to form a silver layer with a thickness. The D90 of the silver particles in the silver layer is less than or equal to 10 μm, that is, 90% of the multiple silver particles in the silver layer have a particle size less than or equal to 10 μm, and the thickness of the silver layer is about 6.3 μm to 6.5 μm. The multiple silver particles in the metal layer 21 are elongated silver particles. The material of the piezoelectric mold layer 22 can be a copolymer. The copolymer can be polyvinylidene fluoride (PDVF). The use of polyvinylidene fluoride as a copolymer is only for illustrative purposes and is not intended to limit the scope of this application.

[0059] By having the metal layer 21 with a thickness of 6.3 μm to 6.5 μm, the first silver layer 4 with a thickness of 6.3 μm to 6.5 μm, and the second silver layer 5 with a thickness of 6.3 μm to 6.5 μm, the first embodiment of this application can achieve a target thickness of 16 μm to 22 μm, thereby optimizing the quality of the ultrasonic signal propagating within the target thickness.

[0060] Please see Figure 4 and Figure 5 As shown, Figure 4 This is a schematic diagram of the structure of the second type of ultrasonic fingerprint recognition module in this application. Figure 4 The text indicates that the ultrasonic emitting layer 2 is bonded to the substrate 1 through the coating layer 3, and the first silver layer 4, the second silver layer 5, and the first insulating layer 6 are stacked sequentially on the ultrasonic emitting layer 2.

[0061] Figure 5 This is a SEM image of the surface condition of silver particles in the second silver layer of the second type of ultrasonic fingerprint recognition module in this application. Figure 5 The surface state of a silver layer formed by coating silver particles, wherein the D90 of the silver particles is less than or equal to 1.6 μm and is spherical.

[0062] This application provides another ultrasonic fingerprint recognition module, including a substrate 1, an ultrasonic emitting layer 2, a coating layer 3, a first silver layer 4, a second silver layer 5, and a first insulating layer 6.

[0063] An ultrasonic emitting layer 2 is provided on the substrate 1. The substrate 1 can be a thin-film transistor (TFT) substrate. The substrate 1 is mainly used as a carrier and simultaneously drives the ultrasonic emitting layer 2 to emit ultrasonic waves through voltage. The substrate 1 can also be used for voltage signal reception.

[0064] A coating layer 3 is provided between the substrate 1 and the ultrasonic emitting layer 2. The coating layer 3 can make the ultrasonic emitting layer 2 and the substrate 1 more firmly bonded. The coating layer 3 can be Primer C.

[0065] The first silver layer 4 is disposed above the ultrasonic emitting layer 2. The first silver layer 4 is formed by coating multiple silver particles and has a thickness. The D90 of the silver particles in the first silver layer 4 is less than or equal to 10 μm, meaning that 90% of the silver particles in the first silver layer 4 have a particle size less than or equal to 10 μm. The D90 particle size of the silver particles in the first silver layer 4 is merely an example and is not intended to limit the application. The thickness of the first silver layer 4 is 6.3 μm to 6.5 μm. The multiple silver particles in the first silver layer 4 are elongated silver particles. The surface of the first silver layer 4 will appear as follows... Figure 3 As shown.

[0066] The second silver layer 5 is disposed above the first silver layer 4. The second silver layer 5 is formed by coating multiple silver particles and has a thickness. The D90 of the silver particles in the second silver layer 5 is less than or equal to 1.6 μm, that is, 90% of the multiple silver particles in the second silver layer 5 have a particle size less than or equal to 1.6 μm. The D90 particle size of the multiple silver particles in the second silver layer 5 is illustrative and is not intended to limit the application. The thickness of the second silver layer 5 is 5 μm to 5.3 μm. In this embodiment, the multiple silver particles in the second silver layer 5 are spherical silver particles, and the surface of the second silver layer 5 will also be as shown. Figure 5 As shown.

[0067] The first insulating layer 6 is disposed above the second silver layer 5. The first insulating layer 6 may be composed of a single layer or multiple layers of insulating material. The insulating material of the first insulating layer 6 may be epoxy resin. In one embodiment, the first insulating layer 6 is provided with at least three layers of insulating material. The first insulating layer 6 is used to protect the second silver layer 5 and the first silver layer 4.

[0068] In this embodiment, the ultrasonic emitting layer 2 is further provided with a metal layer 21 and a piezoelectric mold layer 22. The metal layer 21 is a silver layer with a plurality of silver particles. In other words, the plurality of silver particles are coated to form a silver layer with a thickness. The D90 of the plurality of silver particles is less than or equal to 10 μm, that is, 90% of the particle size of the plurality of silver particles in the metal layer is less than or equal to 10 μm, and the thickness of the silver layer is about 6.3 μm to 6.5 μm. The plurality of silver particles in the metal layer 21 are elongated silver particles. The material of the piezoelectric mold layer 22 can be a copolymer. The copolymer can be polyvinylidene fluoride (PDVF). The use of polyvinylidene fluoride as a copolymer is only for illustrative purposes and is not intended to limit the scope of this application.

[0069] See again Figure 3 and Figure 5 , Figure 3 This is a SEM diagram showing the large D90 of the silver particles in the first silver layer 4 or the second silver layer 5 in the first embodiment of this application, and the silver particles are elongated. Figure 5 This is a SEM diagram showing the smaller D90 and spherical shape of the silver particles in the second silver layer 5 according to the second embodiment of this application. Figure 3 and Figure 5 As can be seen, the second embodiment of this application, which forms a second silver layer 5 with the D90 of these silver particles being less than or equal to 1.6 μm and in a circular shape, can significantly improve the surface fineness of the second silver layer 5 and at the same time improve the uniformity, thereby improving the accuracy of fingerprint recognition.

[0070] Please refer to Table 1 below. Table 1 is a comparison table of silver particles in this application that are elongated and have a large particle size and silver particles that are circular and have a small particle size. The elongated and large particle size refers to the embodiment of the second silver layer 5 of this application where the D90 of the silver particles is large and elongated. The circular and small particle size refers to the embodiment of the second silver layer 5 of this application where the silver particles are small and circular. The elongated and large particle size has an average fingerprint performance index of 0.0256, while the circular and small particle size also has an average fingerprint performance index of 0.01698. By changing the D90 particle size and shape of the silver particles in the second silver layer 5, this application reduces the average fingerprint module performance index. The calculation method is as follows (Equation 1):

[0071]

[0072] As can be seen from the foregoing and Equation 1, the modification of the second silver layer in the second embodiment of this application will reduce the average performance index of the fingerprint module of the second embodiment of this application by 34% compared with the first embodiment.

[0073] Table 1. Comparison of silver particles with elongated shape and large diameter with those with round shape and small diameter.

[0074]

[0075] Table 1 includes a field for the average roughness index. The second silver layer 5 in the first embodiment has an average roughness index of 3.408. The second silver layer 5 in the second embodiment also has an average roughness index of 1.678. Similarly, by changing the D90 particle size and morphology of the silver particles in the second silver layer 5 of the second embodiment, the average roughness index is calculated as follows (Equation 2):

[0076]

[0077] As can be seen from the foregoing, Table 1 and Equation 2, modifying the second silver layer 5 in the second embodiment of this application will reduce the roughness comparison index of the second embodiment of this application by 51% compared with the first embodiment.

[0078] In summary, the main difference between the first and second embodiments of this application is that the original large-diameter, elongated silver particles in the second silver layer 5 are changed to small-diameter, round silver particles. The second silver layer 5 is also formed by coating, thereby improving the performance indicators of the fingerprint module, enhancing fingerprint recognition, and reducing the average roughness index to overcome the problem of unevenness.

[0079] Furthermore, by having a metal layer 21 with a thickness of 6.3 μm to 6.5 μm, a first silver layer 4 with a thickness of 6.3 μm to 6.5 μm, and a second silver layer 5 with a thickness of 5 μm to 5.3 μm, the second embodiment of this application can still achieve the target thickness, and the propagation of the second embodiment of this application can also reach the optimal state within the target thickness, which is 16 μm to 22 μm.

[0080] The above detailed description is a specific description of feasible embodiments of this application. However, the foregoing embodiments are not intended to limit the patent scope of this application. All equivalent implementations or modifications that do not depart from the concept of this application shall fall within the protection scope of this application.

Claims

1. A structure for improving the performance of an ultrasonic fingerprint recognition module, characterized in that, include: substrate; An ultrasonic emitting layer is disposed above the substrate; A coating layer is disposed between the substrate and the ultrasonic emitting layer; A first silver layer is disposed above the ultrasonic emitting layer, and the multiple silver particles in the first silver layer are elongated particles. A second silver layer is disposed above the first silver layer, wherein the plurality of silver particles in the second silver layer are spherical particles; and A first insulating layer is disposed above the second silver layer.

2. The structure for improving the performance of an ultrasonic fingerprint recognition module according to claim 1, characterized in that, The first silver layer has a plurality of silver particles, the D90 of the silver particles in the first silver layer is less than or equal to 10 μm, and the first silver layer has a thickness of 6.5 μm to 6.3 μm.

3. The structure for improving the performance of an ultrasonic fingerprint recognition module according to claim 1, characterized in that, The second silver layer has a plurality of silver particles, the D90 of the silver particles in the second silver layer is less than or equal to 1.6 μm, and the second silver layer has a thickness of 5 μm to 5.3 μm.

4. The structure for improving the performance of an ultrasonic fingerprint recognition module according to claim 1, characterized in that, The substrate is a thin-film transistor substrate.

5. The structure for improving the performance of an ultrasonic fingerprint recognition module according to claim 1, characterized in that, The first insulating layer comprises one or more layers of insulating material.

6. The structure for improving the performance of the ultrasonic fingerprint recognition module according to claim 5, characterized in that, The first insulating layer has at least three layers of insulating material.

7. The structure for improving the performance of an ultrasonic fingerprint recognition module according to claim 5, characterized in that, The insulating material is epoxy resin.

8. The structure for improving the performance of an ultrasonic fingerprint recognition module according to claim 1, characterized in that, The ultrasonic emitting layer contains a metal layer and a piezoelectric film layer.

9. The structure for improving the performance of an ultrasonic fingerprint recognition module according to claim 8, characterized in that, The metal layer is a silver layer, the silver layer has a plurality of silver particles, the D90 of the silver particles of the silver layer is less than or equal to 10 μm, and the silver layer has a thickness of 6.3 μm to 6.5 μm.

10. The structure for improving the performance of an ultrasonic fingerprint recognition module according to claim 9, characterized in that, The silver particles in the silver layer are elongated silver particles.

11. The structure for improving the performance of an ultrasonic fingerprint recognition module according to claim 8, characterized in that, The piezoelectric film layer is a copolymer, and the copolymer is polyvinylidene fluoride.

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