Ultrasonic biometric identification module, preparation method thereof, and electronic device

Abstract

The present invention relates to an ultrasonic biometric identification module, a method for manufacturing the module, and an electronic device. The method for manufacturing the ultrasonic biometric identification module comprises the following steps: providing a thin-film transistor array substrate having a mounting surface, the mounting surface having a mounting area and a binding area separated by a gap; disposing an ink layer on the mounting surface, completely shielding the binding area and leaving the mounting area exposed; forming a piezoelectric layer in the mounting area of the mounting surface, wherein the ink layer is made of a water-soluble ink; removing the ink layer; forming a conductive layer on the side of the piezoelectric layer away from the mounting surface; and forming an acoustic matching layer on the side of the conductive layer away from the piezoelectric layer, thereby obtaining an ultrasonic biometric identification module. The above-described method can produce an ultrasonic biometric identification module with a high yield.

Description

Technical Field

[0001] The present invention relates to the field of biometric identification technology, and in particular to an ultrasonic biometric identification module, a preparation method thereof, and an electronic device. Background Art

[0002] Ultrasonic biometric recognition technology uses ultrasound to scan and analyze living organisms. Typically, an ultrasonic biometric recognition module is created by sequentially stacking a piezoelectric layer, a conductive layer, and an acoustic matching layer on a TFT (Thin Film Transistor) substrate. However, existing processes for producing ultrasonic biometric recognition modules have a low yield and cannot meet practical needs. Summary of the Invention

[0003] Based on this, it is necessary to provide an ultrasonic biometric recognition module with a higher yield and a preparation method thereof.

[0004] In addition, an electronic device is provided.

[0005] A method for preparing an ultrasonic biometric recognition module comprises the following steps:

[0006] Providing a thin film transistor array substrate, wherein the thin film transistor array substrate has a mounting surface, wherein the mounting surface has a mounting area and a binding area spaced apart from each other;

[0007] An ink layer is provided on the mounting surface, wherein the ink layer completely covers the binding area and exposes the mounting area, and a piezoelectric layer is formed in the mounting area of the mounting surface, wherein the material of the ink layer is water-soluble ink;

[0008] removing the ink layer;

[0009] forming a conductive layer on a side of the piezoelectric layer away from the mounting surface; and

[0010] An acoustic matching layer is formed on a side of the conductive layer away from the piezoelectric layer to obtain an ultrasonic biometric recognition module.

[0011] Since the distance between the area where the piezoelectric layer is formed on the TFT substrate and the bonding area is small (generally 170μm), the piezoelectric layer is prone to overflowing into the bonding area, resulting in the presence of insulating material on the bonding area, which affects the binding effect and thus affects the yield of the ultrasonic biometric recognition module. In the above-mentioned method for preparing the ultrasonic biometric recognition module, an ink layer is provided on the mounting surface of the thin film transistor array substrate, the material of the ink layer is water-soluble ink, the ink layer completely covers the binding area and exposes the mounting area, a piezoelectric layer is formed in the mounting area of the mounting surface, and the ink layer is removed so that the ink layer can be removed by washing with water or the like, so that the overflow of the piezoelectric layer in the bonding area is removed at the same time, and basically no residue will remain on the thin film transistor array substrate, which can avoid the piezoelectric layer overflowing (i.e., the material forming the piezoelectric layer overflows) into the binding area to affect the binding effect, improve the binding yield, and obtain an ultrasonic biometric recognition module with a higher yield.

[0012] In one embodiment, the thickness of the ink layer is 10 μm to 15 μm. This configuration not only allows the glue overflow in the binding area of the piezoelectric layer to be removed together with the ink layer, but also makes the ink layer easier to remove, thereby improving the yield of the ultrasonic biometric recognition module.

[0013] In one embodiment, a gap is provided between the mounting area and the binding area, and the ink layer at least partially covers the gap. This configuration can better protect the binding area and improve the yield rate of the ultrasonic biometric recognition module.

[0014] In one embodiment, the distance between the mounting area and the binding area is defined as D1, the distance between the edge of the ink layer closest to the mounting area and the edge of the binding area closest to the mounting area is defined as D2, and the ratio of D2 to D1 ranges from 0 to 1:3. This configuration can better protect the binding area and prevent the ink layer from overflowing into the mounting area and affecting the configuration of the piezoelectric layer.

[0015] In one embodiment, the step of providing an ink layer on the mounting surface includes screen printing the water-soluble ink on the mounting surface and curing the ink layer at 90°C to 130°C. This configuration facilitates rapid curing of the water-soluble ink and improves the adhesion of the ink layer, thereby preventing it from detaching during formation of the piezoelectric layer.

[0016] In one embodiment, the curing time is 5 minutes to 10 minutes. This setting can cure the water-soluble ink to obtain an ink layer with high adhesion.

[0017] In one embodiment, during the step of screen printing the water-soluble ink on the mounting surface, the temperature of the water-soluble ink is 5° C. to 50° C. This setting is conducive to ensuring the physical and chemical properties of the water-soluble ink, so that the formed ink layer is more uniform.

[0018] In one embodiment, in the step of removing the ink layer, the ink layer is removed by water washing, which can effectively remove the ink layer and prevent the corrosion of chemical reagents on the TFT and the piezoelectric layer.

[0019] In one embodiment, after removing the ink layer, the step of drying the thin film transistor array substrate after the ink layer is removed is further included. This configuration prevents residual water from affecting the performance of the ultrasonic biometric recognition module, thereby improving the yield rate of the ultrasonic biometric recognition module.

[0020] An ultrasonic biometric identification module is prepared by the above-mentioned method for preparing an ultrasonic biometric identification module. The ultrasonic biometric identification module has excellent performance and high yield.

[0021] An electronic device includes the ultrasonic biometric recognition module. This electronic device has excellent performance and good biometric recognition performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of an ultrasonic biometric recognition module according to one embodiment;

[0023] Figure 2 for Figure 1 A schematic structural diagram of a thin film transistor array substrate of an ultrasonic biometric recognition module is shown;

[0024] Figure 3 for Figure 2 A schematic structural diagram of a thin film transistor array substrate and an ink layer is shown;

[0025] Figure 4 for Figure 1 The cross-sectional schematic diagram of the ultrasonic biometric recognition module along line VV is shown. DETAILED DESCRIPTION

[0026] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the accompanying drawings. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0028] like Figure 1 As shown, the method for preparing an ultrasonic biometric recognition module 100 according to one embodiment can prepare an ultrasonic biometric recognition module 100 with a high yield. The ultrasonic biometric recognition module 100 can be used for fingerprint recognition. Specifically, the method for preparing the ultrasonic biometric recognition module 100 includes the following steps S110 to S150:

[0029] See also Figure 2 S110, providing a thin film transistor array substrate 110, the thin film transistor array substrate 110 having a mounting surface 112, the mounting surface 112 having spaced mounting areas 112a and binding areas 112c.

[0030] The thin film transistor array substrate 110 is provided with a circuit capable of converting electrical signals into image signals, that is, a thin film transistor (TFT) array is provided on the thin film transistor array substrate 110 for detecting electrical signals at various positions of the piezoelectric layer. The binding area 112c is used to connect the circuit board to achieve binding, that is, the thin film transistor array substrate 110 can be electrically connected to the circuit board through binding. The distance between the mounting area 112a and the binding area 112c is defined as D1. In one embodiment, D1 is 150μm to 1050μm. Further, D1 is 170μm. It should be noted that D1 is not limited to the range indicated above and can be set as needed.

[0031] Please refer to Figures 3-4 S120, an ink layer 114 is provided on the mounting surface 112, the ink layer 114 completely covers the binding area 112c and exposes the mounting area 112a, and a piezoelectric layer 120 is formed in the mounting area 112a of the mounting surface 112. The material of the ink layer 114 is water-soluble ink.

[0032] By setting an ink layer 114 on the mounting surface 112 so that the binding area 112c is covered by the ink layer, in the subsequent process of forming the piezoelectric layer 120 in the mounting area 112a of the mounting surface 112, even if the piezoelectric layer material overflows into the binding area 112c, since the binding area 112c is covered with the ink layer, the overflowed piezoelectric material will adhere to the ink layer. At the same time, water-soluble ink is used as the material of the ink layer 114, so that the subsequent ink layer 114 can be removed by water washing or the like, so as to remove the piezoelectric material attached to the binding area 112c together, and finally the piezoelectric material will not remain in the binding area 112c, which can avoid the piezoelectric layer 120 overflowing (that is, the material forming the piezoelectric layer overflows) to the binding area 112c and affect the binding effect, thereby improving the binding yield. Specifically, the steps of setting an ink layer 114 in a partial area of the mounting surface 112, the ink layer 114 completely covering the binding area 112c, and exposing the mounting area 112a include: setting an ink layer 114 in a partial area of the mounting surface 112, the ink layer 114 completely covering the binding area 112c, and leaving no ink layer 114 on the mounting area 112a of the mounting surface 112.

[0033] In one embodiment, in the step of setting the ink layer 114 in a partial area of the mounting surface 112, the thickness of the ink layer 114 is 10 μm to 15 μm. In some embodiments, the thickness of the ink layer 114 is 10 μm, 11 μm, 12 μm, 13 μm, 14 μm or 15 μm. Setting the ink with such a thickness can not only prevent the overflow of the piezoelectric layer 120 in the binding area 112c from easily penetrating the ink layer 114 and entering the binding area 112c, but also can prevent the ink layer 114 from being too thick and easy to remove. In addition, the above-mentioned ink thickness range setting can improve the binding yield of the binding area 112c, thereby obtaining an ultrasonic biometric recognition module 100 with a higher yield.

[0034] In one embodiment, the ink layer 114 at least partially obscures the gap between the mounting area 112a and the binding area 112c. This configuration can better protect the binding area 112c from adhesive overflow from the piezoelectric layer 120, thereby improving the yield of the ultrasonic biometric recognition module 100. The distance between the edge of the ink layer 114 near the mounting area 112a and the edge of the binding area 112c near the mounting area 112a is defined as D2. In other words, D2 represents the distance that the ink layer 114 overflows the edge of the binding area 112c. D2 ranges from 50 μm to 350 μm.

[0035] In one embodiment, the ratio of D2 to D1 (i.e., the distance between the mounting area 112a and the bonding area 112c) ranges from 0 to 1:3. This configuration can better protect the bonding area 112c and prevent the ink layer 114 from overflowing into the mounting area 112a and affecting the configuration of the piezoelectric layer 120.

[0036] It should be noted that the ink layer 114 is not limited to at least partially covering the gap between the installation area 112a and the binding area 112c. The ink layer 114 can also completely cover the binding area 112c and expose the installation area 112a and the gap between the installation area 112a and the binding area 112c.

[0037] In one embodiment, the step of providing an ink layer 114 on a portion of the mounting surface 112 includes screen printing a water-soluble ink on the portion of the mounting surface 112 and curing the ink layer 114 at a temperature between 90°C and 130°C. This arrangement facilitates rapid curing of the water-soluble ink, improving the adhesion of the ink layer 114 and preventing it from falling off during the formation of the piezoelectric layer 120. Furthermore, the curing time is 5 to 10 minutes. This arrangement enables the water-soluble ink to cure, resulting in an ink layer 114 with high adhesion. Specifically, the adhesion of the ink layer 114 is no less than 4B.

[0038] In one embodiment, during the step of screen-printing a water-soluble ink on a portion of the mounting surface 112, the temperature of the water-soluble ink is 5°C to 50°C. This setting helps ensure the physical and chemical properties of the water-soluble ink, thereby making the formed ink layer 114 more uniform. Furthermore, the temperature of the water-soluble ink is 20°C to 26°C.

[0039] Furthermore, during the step of screen-printing a water-soluble ink on a portion of the mounting surface 112, the ambient temperature is between 5°C and 50°C. Furthermore, the relative humidity of the ambient temperature is below 90%. This setting can ensure the printing effect. Specifically, during the screen-printing process, during the step of screen-printing a water-soluble ink on a portion of the mounting surface 112, the ambient temperature is between 5°C and 50°C. More specifically, the relative humidity of the ambient temperature is between 40% and 70%.

[0040] Water-soluble inks are inks that dissolve in aqueous environments (e.g., water). Furthermore, water-soluble inks also contain hydrophilic groups. Examples of these hydrophilic groups include hydroxyl groups, carboxyl groups, amino groups, or aldehyde groups. Specifically, the water-soluble ink is Elect-2050 water-washable ink. It should be noted that the water-soluble ink is not limited to Elect-2050 water-washable ink; other conventional inks that dissolve in water-washable environments may also be used.

[0041] The piezoelectric layer 120 is capable of transmitting ultrasonic waves, receiving reflected waves from the ultrasonic waves, and converting the reflected waves into electrical signals. It should be noted that the piezoelectric layer 120 is formed in the mounting region 112a of the mounting surface 112 using conventional piezoelectric layer preparation processes. For example, the piezoelectric layer 120 can be obtained by coating the mounting region 112a of the mounting surface 112 with a piezoelectric material, followed by drying, crystallization, and polarization.

[0042] Furthermore, the piezoelectric material is a material commonly used in the art to form a piezoelectric layer. The piezoelectric material may, for example, include a ferroelectric polymer. Furthermore, the ferroelectric polymer may, for example, be P(VDF-TrFE) (a copolymer of polyvinylidene chloride and trifluoroethylene). It should be noted that the ferroelectric polymer is not limited to the substances mentioned above, and may also be a homopolymer of polyvinylidene chloride, a copolymer of polyvinylidene chloride, a homopolymer of polytetrafluoroethylene, a copolymer of polytetrafluoroethylene, diisopropylamine bromide (DTPAB) or polyvinylidene fluoride, etc. It should be noted that the piezoelectric material is not limited to including a ferroelectric polymer, and may also include a solvent. The solvent may, for example, be methyl ethyl ketone, dimethylacetamide and propylene glycol methyl ether acetate, etc.

[0043] Specifically, the piezoelectric material is applied to the mounting area 112a of the mounting surface 112 by coating. It should be noted that the piezoelectric material is not limited to coating, and can also be applied by screen printing or spraying.

[0044] The purpose of drying is to form a piezoelectric green body layer from the piezoelectric material, so as to facilitate the formation of a denser piezoelectric layer 120 during the subsequent crystallization process. It should be noted that the drying is performed using conventional drying processes in the art, for example, drying at 60° C. to 80° C. for 0.5 to 2 hours.

[0045] The purpose of crystallization is to form a dense piezoelectric layer 120 from the piezoelectric green body layer, thereby obtaining a piezoelectric layer 120 with good piezoelectric performance. It should be noted that the crystallization process is performed using conventional crystallization processes in the art, for example, by maintaining the temperature at 135° C. to 145° C. for 3 to 6 hours.

[0046] It should be noted that the polarization treatment is performed using a conventional polarization process in the art, such as corona discharge.

[0047] S130 , removing the ink layer 114 .

[0048] In one embodiment, the ink layer 114 is removed by water washing. Water washing effectively removes the ink layer 114 while preventing chemical agents from corroding the TFT and piezoelectric layer 120. It also reduces costs and is non-toxic. Furthermore, water washing is performed at room temperature. This allows the ink layer 114 to dissolve more quickly, allowing for quick and complete removal.

[0049] Specifically, the step of removing the ink layer 114 includes wiping the ink layer 114 with a wet wiper to remove the ink layer 114. Wiping the ink layer 114 avoids direct water spraying or soaking, which would require a prolonged drying time of the thin-film transistor array substrate 110 after the ink layer 114 is removed. The wiper may be, for example, a dust-free cloth or gauze. It should be noted that the removal of the ink layer 114 is not limited to wiping the ink layer 114 with a wet wiper. An automatic water washing machine may also be used to wash the thin-film transistor array substrate 110 with the ink layer 114 formed thereon to remove the ink layer 114.

[0050] In one embodiment, after removing the ink layer 114, the step of drying the thin-film transistor array substrate 110 from which the ink layer 114 has been removed is also included. This configuration prevents residual water from affecting the performance of the ultrasonic biometric recognition module 100, thereby improving the yield of the ultrasonic biometric recognition module 100. Furthermore, the drying method includes wiping the surface of the thin-film transistor array substrate 110 and the surface of the piezoelectric layer 120 with a dry and clean wipe. The wipe can be, for example, a dust-free cloth or gauze.

[0051] S140 , forming a conductive layer 130 on a side of the piezoelectric layer 120 away from the mounting surface 112 .

[0052] It should be noted that the conductive layer 130 is formed on the side of the piezoelectric layer 120 away from the mounting surface 112 by using a conventional process for forming a conductive layer in the art.

[0053] In one specific example, the conductive layer 130 comprises two layers. The two conductive layers 130 are sequentially stacked on the piezoelectric layer 120. Providing two conductive layers 130 can make the conductivity more uniform, which is beneficial for charge conduction. Furthermore, the material of the two conductive layers 130 is silver. Both conductive layers 130 are obtained by screen printing silver paste and then sintering. It should be noted that the conductive layer 130 is not limited to two layers and can also be one layer or more than two layers.

[0054] S150 , forming an acoustic matching layer 140 on a side of the conductive layer 130 away from the piezoelectric layer 120 , thereby obtaining the ultrasonic biometric recognition module 100 .

[0055] The acoustic matching layer 140 protects the conductive layer 130 and reflects ultrasonic signals. Furthermore, the step of forming the acoustic matching layer 140 on the side of the conductive layer 130 facing away from the piezoelectric layer 120 includes laminating the acoustic matching layer 140 to the side of the conductive layer 130 facing away from the piezoelectric layer 120. The acoustic matching layer 140 is made of a conventional acoustic matching material in the art, such as a solid adhesive film. It should be noted that the acoustic matching layer 140 is not limited to a solid adhesive film and may also be other film materials, such as a die attach film (DAF).

[0056] In the illustrated embodiment, the acoustic matching layer 140 is located on the conductive layer 130 away from the piezoelectric layer 120 .

[0057] It should be noted that the steps of S130, S140 and S150 are not limited, and S130, S140 and S150 may be performed in sequence, or S140, S150 and S130 may be performed in sequence, or S140, S130 and S150 may be performed in sequence.

[0058] In one embodiment, after forming the acoustic matching layer 140 on the side of the conductive layer 130 away from the piezoelectric layer 120, the following step is further included: providing a circuit board (not shown) to electrically connect the thin-film transistor array substrate 110 and the conductive layer 130. Furthermore, the circuit board is bonded to the bonding area 112c of the thin-film transistor array substrate 110 and to the conductive layer 130 near the piezoelectric layer 120. More specifically, the circuit board is a flexible circuit board.

[0059] Since the distance between the area where the piezoelectric layer is formed and the bonding area on the TFT substrate is small (generally 170μm), the piezoelectric layer is prone to overflowing into the bonding area, resulting in the presence of insulating material in the bonding area and affecting the bonding effect, thereby affecting the yield of the ultrasonic biometric recognition module. In the preparation method of the ultrasonic biometric identification module 100 of the above embodiment, an ink layer 114 is set on a partial area of the mounting surface 112 of the thin film transistor array substrate 110. The material of the ink layer 114 is water-soluble ink. The ink layer 114 completely covers the binding area 112c and exposes the mounting area 112a. A piezoelectric layer 120 is formed in the mounting area 112a of the mounting surface 112. The ink layer 114 is removed so that the ink layer 114 can be removed by washing with water or the like, so as to remove the overflow of the piezoelectric layer 120 in the binding area 112c at the same time, and basically no residue will remain on the thin film transistor array substrate 110. It can avoid affecting the binding effect due to the overflow of the piezoelectric layer 120 to the binding area 112c, improve the binding yield of the binding area 112c, and obtain an ultrasonic biometric identification module 100 with a higher yield.

[0060] In the method for preparing the ultrasonic biometric recognition module 100 of the aforementioned embodiment, the ink layer 114 completely obscures the binding area 112c and exposes the mounting area 112a. This ensures that the ink layer 114 does not affect the formation of the piezoelectric layer 120, for example, the drying, crystallization, and polarization of the piezoelectric material. Furthermore, the ink layer 114 is made of a water-soluble ink, allowing it to be washed away after polarization without leaving any residue on the TFT, thereby ensuring the yield of the ultrasonic biometric recognition module 100. Furthermore, the screen printing precision requirements for water-soluble inks are relatively low, and the screen printing accuracy and coating accuracy of the screen printing machine can meet the coating requirements for water-soluble inks.

[0061] To prevent the piezoelectric layer from overflowing into the binding area and affecting the yield of the ultrasonic biometric module after binding, the coating accuracy of the conductive layer needs to be improved. The accuracy of existing coating equipment is unstable and cannot meet practical requirements. However, in the method for preparing the ultrasonic biometric module 100 of the above embodiment, the provision of the ink layer 114 can prevent the piezoelectric layer 120 from overflowing into the binding area 112c and affecting the binding effect. This can reduce the coating accuracy requirements for the conductive layer 130 and improve coating efficiency.

[0062] An electronic device, such as a mobile phone or computer, includes an ultrasonic biometric recognition module 100 prepared by the method for preparing the ultrasonic biometric recognition module 100 according to the embodiment described above. This electronic device has excellent performance and good biometric recognition performance.

[0063] The following is a specific example section.

[0064] In the following examples, unless otherwise specified, the water-soluble ink is Elect-2050 water-washable ink.

[0065] Example 1

[0066] 20 ultrasonic biometric recognition modules were prepared according to the following operation. Specifically, the preparation process of the ultrasonic biometric recognition module is as follows:

[0067] A thin film transistor array substrate is provided. The thin film transistor array substrate has a mounting surface. The mounting surface has a mounting area and a binding area spaced apart from each other. The spacing between the mounting area and the binding area is 150 μm.

[0068] A water-soluble ink was screen-printed on the mounting surface at 5°C and 40% relative humidity. The ink layer was cured at 90°C for 5 minutes to completely cover the bonding area and leave the mounting area exposed. The distance between the edge of the ink layer closest to the mounting area and the edge of the bonding area closest to the mounting area was 50 μm. The ink layer thickness was 10 μm. Piezoelectric material was then applied to the mounting area of the mounting surface, followed by drying, crystallization, and polarization to form the piezoelectric layer.

[0069] Wipe with a dust-free cloth soaked in water at room temperature to remove the ink layer, and then wipe dry with a dry, clean dust-free cloth.

[0070] A conductive layer is formed on a side of the piezoelectric layer away from the mounting surface.

[0071] An acoustic matching layer is formed on a side of the conductive layer away from the piezoelectric layer to obtain an ultrasonic biometric recognition module.

[0072] Example 2

[0073] 20 ultrasonic biometric recognition modules were prepared according to the following operation. Specifically, the preparation process of the ultrasonic biometric recognition module is as follows:

[0074] A thin film transistor array substrate is provided. The thin film transistor array substrate has a mounting surface. The mounting surface has a mounting area and a binding area spaced apart from each other. The spacing between the mounting area and the binding area is 1050 μm.

[0075] A water-soluble ink was screen-printed on the mounting surface at 50°C and 70% relative humidity. The ink layer was cured at 130°C for 10 minutes to form an ink layer that completely covered the bonding area and left the mounting area exposed. The distance between the edge of the ink layer closest to the mounting area and the edge of the bonding area closest to the mounting area was 350μm. The ink layer thickness was 15μm. Piezoelectric material was then applied to the mounting area of the mounting surface, followed by drying, crystallization, and polarization to form the piezoelectric layer.

[0076] Wipe with a dust-free cloth soaked in water at room temperature to remove the ink layer, and then wipe dry with a dry, clean dust-free cloth.

[0077] A conductive layer is formed on a side of the piezoelectric layer away from the mounting surface.

[0078] An acoustic matching layer is formed on a side of the conductive layer away from the piezoelectric layer to obtain an ultrasonic biometric recognition module.

[0079] Example 3

[0080] 20 ultrasonic biometric recognition modules were prepared according to the following operation. Specifically, the preparation process of the ultrasonic biometric recognition module is as follows:

[0081] A thin film transistor array substrate is provided. The thin film transistor array substrate has a mounting surface. The mounting surface has a mounting area and a binding area spaced apart from each other. The spacing between the mounting area and the binding area is 170 μm.

[0082] A water-soluble ink was screen-printed on the mounting surface at 25°C and 55% relative humidity. The ink layer was cured at 110°C for 7 minutes to form an ink layer that completely covered the bonding area and left the mounting area exposed. The distance between the edge of the ink layer closest to the mounting area and the edge of the bonding area closest to the mounting area was 200 μm. The ink layer thickness was 12 μm. Piezoelectric material was then applied to the mounting area of the mounting surface, followed by drying, crystallization, and polarization to form the piezoelectric layer.

[0083] At room temperature, wipe with a dust-free cloth soaked in water to remove the ink layer, and then wipe dry with a dry and clean dust-free cloth to obtain a piezoelectric layer.

[0084] A conductive layer is formed on a side of the piezoelectric layer away from the mounting surface.

[0085] An acoustic matching layer is formed on a side of the conductive layer away from the piezoelectric layer to obtain an ultrasonic biometric recognition module.

[0086] Example 4

[0087] 20 ultrasonic biometric recognition modules were prepared according to the following operation. Specifically, the preparation process of the ultrasonic biometric recognition module is as follows:

[0088] A thin film transistor array substrate is provided. The thin film transistor array substrate has a mounting surface. The mounting surface has a mounting area and a binding area spaced apart from each other. The spacing between the mounting area and the binding area is 170 μm.

[0089] At 25°C and 55% relative humidity, a commercially available removable adhesive was applied to the mounting surface to form an adhesive layer. This layer completely covered the bonding area, leaving the mounting area exposed. The distance between the edge of the adhesive layer closest to the mounting area and the edge of the bonding area closest to the mounting area was 200 μm. The adhesive layer had a thickness of 12 μm. Piezoelectric material was then applied to the mounting area of the mounting surface, followed by drying, crystallization, and polarization to form a piezoelectric layer.

[0090] Peel off the adhesive layer.

[0091] A conductive layer is formed on a side of the piezoelectric layer away from the mounting surface.

[0092] An acoustic matching layer is formed on a side of the conductive layer away from the piezoelectric layer to obtain an ultrasonic biometric recognition module.

[0093] Example 5

[0094] 20 ultrasonic biometric recognition modules were prepared according to the following operation. Specifically, the preparation process of the ultrasonic biometric recognition module is as follows:

[0095] A thin film transistor array substrate is provided. The thin film transistor array substrate has a mounting surface. The mounting surface has a mounting area and a binding area spaced apart from each other. The spacing between the mounting area and the binding area is 170 μm.

[0096] The piezoelectric material is coated on the mounting area of the mounting surface, and is dried, crystallized and polarized in sequence to obtain a piezoelectric layer.

[0097] A conductive layer is formed on a side of the piezoelectric layer away from the mounting surface.

[0098] An acoustic matching layer is formed on a side of the conductive layer away from the piezoelectric layer to obtain an ultrasonic biometric recognition module.

[0099] test:

[0100] The binding yield rate of the ultrasonic biometric recognition module in the binding area of Examples 1 to 5, the adhesion of the ink layer in the preparation process of Examples 1 to 3, and the adhesive layer of Example 4 were measured. The measurement results are detailed in Table 1. Table 1 shows the binding yield rate of the ultrasonic biometric recognition module in the binding area of Examples 1 to 5, the adhesion of the ink layer in the preparation process of Examples 1 to 3, and the adhesive layer of Example 4. "--" in Table 1 means that no test was performed. Among them, the binding yield rate of the ultrasonic biometric recognition module in the binding area was measured using existing methods or devices; the adhesion was measured using a hundred-grid test.

[0101] Table 1

[0102] Binding yield (%) Adhesion Example 1 99.5 4B Example 2 99.6 4B Example 3 99.9 5B Example 4 97.3 4B Example 5 95.1 --

[0103] As shown in Table 1, the binding yield rate of the ultrasonic biometric recognition modules in Examples 1-3 in the binding area is over 99.5%, which is superior to that of Examples 4-5. This demonstrates that the preparation method of the above embodiment can improve the yield rate in the binding area, resulting in ultrasonic biometric recognition modules with a high yield rate. Furthermore, the adhesion of the ink layer during the preparation of the ultrasonic biometric recognition modules in Examples 1-3 was 4B to 5B, indicating that the ink layer in the preparation method of the above embodiment has high adhesion and is not easily detached during the preparation of the piezoelectric layer.

[0104] In summary, in the above-mentioned method for preparing the ultrasonic biometric recognition module, the provision of the ink layer can improve the binding yield of the binding area, thereby obtaining an ultrasonic biometric recognition module with a higher yield, which can be used to prepare electronic products with excellent performance.

[0105] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0106] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing an ultrasonic biometric recognition module, characterized in that: The steps include: Providing a thin film transistor array substrate, wherein the thin film transistor array substrate has a mounting surface, wherein the mounting surface has a mounting area and a binding area spaced apart from each other; An ink layer is provided on the mounting surface, wherein the ink layer completely covers the binding area and exposes the mounting area, and a piezoelectric layer is formed in the mounting area of the mounting surface, wherein the material of the ink layer is water-soluble ink; Washing with water to remove the ink layer, wherein the thickness of the ink layer is 10 μm to 15 μm; forming a conductive layer on a side of the piezoelectric layer away from the mounting surface; and forming an acoustic matching layer on a side of the conductive layer away from the piezoelectric layer to obtain an ultrasonic biometric recognition module; The distance between the installation area and the binding area is defined as D1, and the distance between the edge of the ink layer close to the installation area and the edge of the binding area close to the installation area is defined as D2. The ratio of D2 to D1 ranges from 0 to 1:

3.

2. The method for preparing an ultrasonic biometric recognition module according to claim 1, wherein: There is a gap between the installation area and the binding area, and the ink layer at least partially covers the gap.

3. The method for preparing an ultrasonic biometric recognition module according to claim 1, wherein: The step of providing the ink layer on the mounting surface comprises: screen printing the water-soluble ink on the mounting surface, curing the ink at 90° C. to 130° C., and obtaining the ink layer.

4. The method for preparing an ultrasonic biometric recognition module according to claim 3, wherein: The curing time is 5 minutes to 10 minutes.

5. The method for preparing an ultrasonic biometric recognition module according to claim 3, wherein: In the step of screen-printing the water-soluble ink on the substrate, the temperature of the water-soluble ink is 5° C. to 50° C.

6. The method for preparing an ultrasonic biometric recognition module according to claim 1, wherein: After the step of removing the ink layer, the method further includes a step of drying the thin film transistor array substrate after the ink layer is removed.

7. An ultrasonic biometric recognition module, characterized in that: The ultrasonic biometric identification module is prepared by the preparation method of any one of claims 1 to 6.

8. An electronic device, characterized in that: Including the ultrasonic biometric recognition module as described in claim 7.

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