Fingerprint recognition module thinning method

Abstract

A method for thinning a fingerprint recognition module comprises providing a light-transmitting substrate, physically polishing a first surface of the light-transmitting substrate, forming a polyimide (PI) film on the first surface, etching and thinning a second surface of the light-transmitting substrate and physically polishing the second surface of the light-transmitting substrate, preparing a thin film transistor (TFT) array on the second surface, forming a fingerprint recognition printed coating on the thin film transistor (TFT) array, irradiating the polyimide film with excimer laser light, removing the polyimide film, and performing a knife wheel cutting or laser cutting on the light-transmitting substrate to obtain a plurality of fingerprint recognition modules.

Description

Technical Field

[0001] The present invention relates to a fingerprint recognition module, and in particular to a method for thinning a light-transmitting substrate in the fingerprint recognition module. Background Art

[0002] With the development of science and technology and the upgrading of consumer demand, the requirements for portable electronic devices to be lighter and thinner are getting higher and higher. For portable electronic devices with traditional flat-panel displays, the thickness of a single-layer transparent substrate reaches 0.4 mm to 0.5 mm, or the thickness of a liquid crystal display device formed by two layers of transparent substrates plus liquid crystal filling in the middle is about 1.0 mm, which is difficult to meet the demand for "light and thin" display devices.

[0003] In order to achieve the requirements of lightness and thinness, manufacturers have begun to adopt thinning technology for the thickness of light-transmitting substrates. Display panels have been thinned from 0.5 mm (or above) to 0.4 mm, 0.3 mm, 0.2 mm or even 0.1 mm, so as to achieve the purpose of lightness and thinness.

[0004] In the near future, fingerprint (FP) recognition electronic products need to thin the glass because the ultrasonic energy will decrease during the transmission process. The common mainstream is to thin the single board from 0.5 mm to 0.09 mm. There are even thinner application requirements to reflect better fingerprint recognition images. The common process is to thin the thin film transistor (TFT) substrate after the fingerprint (FP) recognition printing is completed.

[0005] Applying the thinning technology of traditional liquid crystal display devices to fingerprint recognition components also has the following problems: low output, resulting in poor economic benefits; thinning technology requires coating with a secondary acid-resistant film, which is expensive and has a complicated process; or because of the use of acid-resistant sealant, a cutting process is required, and the cutting process will have uneven edges and poor quality, which will lead to a reduction in yield and increase in product costs.

[0006] In addition, when the thickness of the current fingerprint (FP) recognition products is reduced, warping will occur due to the mismatch between the thermal expansion coefficient (CTE) αa of the organic coating and the thermal expansion coefficient (CTE) αb of the inorganic glass.

[0007] As the glass thickness (t) decreases, the warpage will become more serious, causing a significant increase in the breakage rate of thinning. Therefore, the difficulty of operation will increase significantly as the thinning thickness target decreases and the thinning size of the product increases. Summary of the invention

[0008] In view of the problems of the background technology, one purpose of the present invention is to provide a method for thinning a fingerprint recognition module, using a polyimide (PI) laser lift off (LLO) process to change the process sequence of component printing and thinning, and to achieve the purpose of reducing the breakage rate in the cutting process and improving the production capacity.

[0009] According to another purpose of the present invention, in addition to providing the fingerprint recognition module with a bearing structure to support the thinned glass and protect the glass surface, it can also avoid roller marks and touch damage caused by the subsequent thin film transistor (TFT) process, reduce the difficulty of glass thinning and polishing, and increase the thickness and size after thinning.

[0010] According to the purpose of the present invention, a method for thinning a fingerprint recognition module is provided, comprising the following steps: providing a transparent substrate, the transparent substrate having a corresponding first surface and a second surface, physically polishing the first surface, performing a coating operation on the first surface to form a polyimide (PI) film, etching and thinning the second surface and physically polishing the second surface, preparing a thin film transistor (TFT) array on the second surface, forming a fingerprint recognition printed coating on the thin film transistor (TFT) array, exposing the fingerprint recognition printed coating, irradiating an excimer laser light to the polyimide film, removing the polyimide film, and performing a knife wheel cutting or laser cutting on the transparent substrate to obtain a plurality of fingerprint recognition modules.

[0011] In one embodiment, the transparent substrate is an alkali-free transparent substrate, and before the coating operation, an inspection is performed to check whether there are any defects in the appearance of the transparent substrate, whether the polishing degree (Ra value) of physical polishing is the same, and measure the thickness of the transparent substrate to confirm whether the thickness of the transparent substrate needs to be adjusted after etching and thinning.

[0012] In one embodiment, the polyimide film is formed on the first surface to protect the first surface. When the transparent substrate is thinned to a predetermined specification, the polyimide film supports the transparent substrate to perform an etching thinning process.

[0013] In one embodiment, the coating operation is to transfer the polyimide film using a wet or evaporation process.

[0014] In one embodiment, the wavelength of the excimer laser light is between 308 nm and 351 nm.

[0015] In one embodiment, a light source is used in the process of manufacturing the thin film transistor (TFT) array, and the light source does not react with the polyimide film.

[0016] In one embodiment, after the fingerprint identification printed coating is exposed to ultraviolet light, the transparent substrate can be cut by a knife wheel or laser, and then an excimer laser is irradiated to the polyimide film to remove the polyimide film to obtain multiple fingerprint identification modules.

[0017] According to the purpose of the present invention, the present invention provides another method for thinning a fingerprint recognition module, comprising the following steps: providing a transparent substrate, the transparent substrate having a corresponding first surface and a second surface, physically polishing the first surface, performing a coating operation on the first surface to form a polyimide (PI) film, assembling a carrier on the polyimide film, etching and thinning the second surface and physically polishing it, preparing a thin film transistor (TFT) array on the second surface, printing a fingerprint recognition stack on the thin film transistor (TFT) array, exposing the fingerprint recognition stack, irradiating the carrier with an excimer laser light, removing the polyimide film and the carrier, and performing a knife wheel cutting or laser cutting on the transparent substrate to obtain a plurality of fingerprint recognition modules.

[0018] In one embodiment, the thin film transistor (TFT) array includes a silicon oxide layer and a metal layer. The silicon oxide layer is disposed on the second surface, and the metal layer is located on the silicon oxide layer.

[0019] In one embodiment, the transparent substrate is an alkali-free transparent substrate, and the first surface is protected by the polyimide film and the carrier. When the transparent substrate is thinned to a predetermined specification, the polyimide film and the carrier support the transparent substrate to perform an etching thinning process.

[0020] In one embodiment, after the thinned fingerprint recognition module is manufactured, a finished product factory inspection is performed and the thickness of the transparent substrate is measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a step diagram of an embodiment of the present invention.

[0022] Figure 2 It is a schematic diagram of a manufacturing process of an embodiment of the present invention.

[0023] Figure 3 It is a step diagram of another embodiment of the present invention.

[0024] Figure 4 It is a schematic diagram of the manufacturing process of another embodiment of the present invention.

[0025] The accompanying drawings are marked as follows:

[0026] 1: Translucent substrate

[0027] 11: First surface

[0028] 12: Second Surface

[0029] 2: Polyimide film

[0030] 3: Thin Film Transistor Array

[0031] 4: Fingerprint recognition printing coating

[0032] 4': Fingerprint recognition stack

[0033] 5: Excimer laser light

[0034] 6: Fingerprint recognition module

[0035] 7: Carrier

[0036] S101~S111: Steps

[0037] S201~S212: Steps DETAILED DESCRIPTION

[0038] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0039] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in the present specification are for illustrative purposes only and do not represent the only implementation method.

[0040] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "multiple" or "plural" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0041] In the present invention, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first feature is directly in contact with the second feature, or the first feature and the second feature are indirectly in contact through an intermediate medium. Moreover, a first feature being “above”, “above” or “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “above”, “above” or “above” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0042] Unless otherwise defined, all technical and scientific terms used in the specification of the present invention have the same meaning as those commonly known to those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in the specification of the present invention includes any and all combinations of one or more related listed items.

[0043] See also Figure 1 and Figure 2 As shown, the present invention provides a method for thinning a fingerprint recognition module, comprising the following steps:

[0044] S101: Provide a transparent substrate 1, wherein the transparent substrate 1 has a corresponding first surface 11 and a second surface 12. In this embodiment, the transparent substrate 1 is an alkali-free transparent substrate, such as a glass substrate.

[0045] S102: performing physical polishing on the first surface 11.

[0046] S103 : performing a coating operation on the first surface 11 to form a polyimide (PI) film 2 .

[0047] In this embodiment, the polyimide film 2 protects the first surface 11, and at the same time, the polyimide film 2 supports the transparent substrate 1 with sufficient mechanical strength for physical polishing and etching thinning processes. In addition, the coating operation is to transfer the polyimide film 2 using a wet or evaporation process.

[0048] That is to say, in the above method, the polyimide film 2 can support the thinned transparent substrate 1 and protect the first surface 11 .

[0049] It should be further explained that before the coating operation is performed, an inspection is first performed to check whether the transparent substrate 1 has any defects in its appearance and whether the polishing degree (Ra value) of physical polishing is the same.

[0050] S104: Etching and thinning the second surface 12. After the transparent substrate 1 is thinned, the thickness of the transparent substrate 1 after thinning is measured to confirm whether the thickness of the transparent substrate 1 after etching and thinning reaches a predetermined specification. In this embodiment, the predetermined specification is 90+ / -20 microns (um). After the transparent substrate 1 is thinned by etching, another physical polishing operation can be performed to make the surface polishing degree (Ra value) of the transparent substrate 1 the same.

[0051] S105: a thin film transistor (TFT) array 3 is disposed on the second surface 12. In this step, it should be further explained that a light source is used in the process of preparing the thin film transistor (TFT) array 3, and the light source does not react with the polyimide film 2.

[0052] S106: forming a fingerprint identification printing coating 4 on the thin film transistor (TFT) array 3. In this embodiment, the thickness of the fingerprint identification printing coating 4 is 40+ / -8 (um).

[0053] S107: Expose the fingerprint identification printed coating 4. In this step, the light source used for exposure can be invisible light.

[0054] S108: Expose an excimer laser light 5 to the polyimide film 2. In this embodiment, the wavelength of the excimer laser light 5 is between 308 nm and 351 nm. In addition, it should be noted in this step that, because the fingerprint identification printing coating 4 has a metal coating that will reflect the light source of the polyimide (PI) laser lift off, LLO, only one side of the polyimide film 2 can be exposed to the excimer laser light 5, so the polyimide film 2 needs to have sufficient laser transmittance.

[0055] S109: removing the polyimide film 2.

[0056] S110: performing a knife wheel cutting or a laser cutting on the light-transmitting substrate 1 .

[0057] S111: Acquire multiple fingerprint recognition modules 6.

[0058] It should be additionally explained that, in order to achieve the purpose of separating the polyimide film 2 and the transparent substrate 1 having the thin film transistor (TFT) array 3, in the above steps, after the fingerprint identification printed coating 4 is exposed to ultraviolet light, the transparent substrate 1 can also be firstly cut by a knife wheel or laser, and then an excimer laser light 5 is irradiated to the polyimide film 2 to remove the polyimide film 2 and obtain a plurality of fingerprint identification modules 6.

[0059] See also Figure 3 and Figure 4 As shown, the present invention provides another method for thinning a fingerprint recognition module, comprising the following steps:

[0060] S201: Provide a transparent substrate 1, the transparent substrate 1 having a corresponding first surface 11 and a second surface 12. In this embodiment, the transparent substrate 1 is an alkali-free transparent substrate, such as a glass substrate.

[0061] S202: performing physical polishing on the first surface 11.

[0062] S203 : performing a coating operation on the first surface 11 to form a polyimide (PI) film 2 .

[0063] In this embodiment, the polyimide film 2 protects the first surface 11, and at the same time, the polyimide film 2 supports the transparent substrate 1 with sufficient mechanical strength for physical polishing and etching thinning processes. In addition, the coating operation is to transfer the polyimide film 2 by a wet or evaporation process.

[0064] It should be noted that, before the coating operation is performed, an inspection is first performed to check whether the transparent substrate 1 has any defects in its appearance and whether the polishing degree (Ra value) of physical polishing is the same.

[0065] S204: a carrier 7 is disposed on the polyimide film 2. In this embodiment, the carrier 7 has sufficient mechanical strength and flatness and is capable of allowing laser penetration. In other words, the polyimide film 2 becomes an adhesive layer between the transparent substrate 1 and the carrier 7, supporting the transparent substrate 1 so that it has sufficient mechanical strength for the etching thinning process.

[0066] In addition, the carrier 7 can be regarded as a structural substrate with high mechanical strength, the purpose of which is to provide the thinned transparent substrate with sufficient rigidity. The carrier 7 can be a plastic molecular material such as PVC, or it can be white glass, so that it can be compatible with subsequent thin film transistor (TFT) array processes, fingerprint printing processes, and etching thinning processes.

[0067] S205: etching and thinning the second surface 12.

[0068] After the transparent substrate 1 is thinned, the thickness of the transparent substrate 1 is measured to confirm whether the thickness of the transparent substrate 1 after etching and thinning is within a predetermined specification. In this embodiment, the predetermined specification is 90+ / -20 microns (um). After the transparent substrate 1 is thinned by etching, another physical polishing operation can be performed to make the surface polishing degree (Ra value) of the transparent substrate 1 the same.

[0069] S206: a thin film transistor (TFT) array 3 is disposed on the second surface 12. In this embodiment, the thin film transistor (TFT) array 3 includes a silicon oxide layer 31 and a metal layer 32, wherein the silicon oxide layer 31 is disposed on the second surface 12, and the metal layer 32 is located on the silicon oxide layer 31. In this step, it should be further explained that a light source is used in the process of preparing the thin film transistor (TFT) array 3, and the light source does not react with the polyimide film 2.

[0070] S207: Print a fingerprint identification stack 4' on the thin film transistor (TFT) array 3. In this embodiment, the printing thickness of the fingerprint identification stack 4 is 40+ / -8 (um).

[0071] S208: Expose the fingerprint identification stack 4' to ultraviolet light.

[0072] S209: Expose the carrier 7 with an excimer laser beam 5. It should be noted in this step that, because the fingerprint identification stack 4 has a metal coating that will reflect the light source of the LLO, the excimer laser beam 5 is only applied to one side of the carrier 7, so the polyimide film 2 and the carrier 7 need to have sufficient laser transmittance.

[0073] S210 : removing the polyimide film 2 and the carrier 7 .

[0074] S211: performing a knife wheel cutting or a laser cutting on the light-transmitting substrate 1 .

[0075] S212: Acquire multiple fingerprint recognition modules 6.

[0076] In the above, the steps of this embodiment are different from the normal process. The normal process is to first produce thin film transistors (TFT), then screen print ink to form fingerprint recognition elements, and finally perform thinning process. In the steps of this embodiment, the glass thinning process is moved to the polyimide film 2 and the transparent substrate 1 at the beginning. Because there is no influence of organic coating, the product does not warp, which can improve the yield of the thinning of the transparent substrate 1.

[0077] It should be noted that after the thinned fingerprint recognition module 6 is manufactured, a finished product factory inspection is performed and the thickness of the transparent substrate 1 is measured. The finished product factory inspection is to check whether the surface of the fingerprint recognition module 6 is defective due to scratches and bruises.

[0078] In summary, the present invention provides a method for thinning a fingerprint recognition module. The fingerprint recognition module manufacturing process is supplemented with a polyimide (PI) laser lift off (LLO) process, and the process sequence of component printing and thinning in the fingerprint recognition module is changed. Polyimide (PI) is used as a carrier or an adhesive layer between glass and a carrier to protect the surface of the transparent substrate. Before the transparent substrate completes the TFT process, the transparent substrate is thinned to meet the thickness specification required by the fingerprint recognition component. Finally, a laser lift off (LLO) procedure is performed after the fingerprint coating process to complete the separation of the polyimide film from the transparent substrate.

[0079] That is, a polyimide laser lift-off process is adopted for the transparent substrate, and a TFT process and a fingerprint recognition printed coating are simultaneously performed on the thinned transparent substrate, and then the transparent substrate is cut to obtain a plurality of fingerprint recognition modules.

[0080] In addition, the first surface in the above method is the key surface that mainly affects the image after the transparent substrate is thinned. In addition, the above method can reduce the difficulty of glass thinning and polishing, thereby increasing the thinning thickness and size.

[0081] Furthermore, it is additionally stated that the thinning method of the fingerprint recognition module of the present invention is not limited to protecting the polyimide film (PI) on the working surface of the glass thinning, and the polyimide film (PI) can be integrated into the TFT process and implemented on the thinning surface of the non-light-transmissive substrate.

[0082] The above detailed description is a specific description of the feasible embodiments of the present invention. However, the aforementioned embodiments are not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the technical spirit of the present invention should be included in the patent scope of this case.

Claims

1. A method for thinning a fingerprint recognition module, characterized in that: The following steps are involved: Providing a light-transmitting substrate, wherein the light-transmitting substrate has a first surface and a second surface corresponding to each other; forming a polyimide film on the first surface, wherein the polyimide film protects the first surface and supports the thinned transparent substrate; etching and thinning the second surface; Disposing a thin film transistor array on the second surface; forming a fingerprint identification printed coating on the thin film transistor array; exposing the fingerprint identification printed coating; irradiating the polyimide film with excimer laser light; The polyimide film is removed.

2. The method for thinning a fingerprint recognition module as claimed in claim 1, characterized in that: After providing the light-transmitting substrate and before forming the polyimide film on the first surface, the step of physically polishing the first surface is performed.

3. The method for thinning a fingerprint recognition module as claimed in claim 1, characterized in that: After etching and thinning the second surface, before arranging a thin film transistor array on the second surface, a step is performed: physically polishing the second surface.

4. The method for thinning a fingerprint recognition module as claimed in claim 1, characterized in that: When the fingerprint identification printed coating is exposed, the light source used is invisible light.

5. The method for thinning a fingerprint recognition module as claimed in claim 1, wherein: The wavelength of the excimer laser light source ranges from 308 nanometers to 351 nanometers.

6. The method for thinning a fingerprint recognition module as claimed in claim 1, wherein: After removing the polyimide film, the step of: performing a knife wheel cutting or a laser cutting on the transparent substrate is performed.

7. The method for thinning a fingerprint recognition module as claimed in claim 1, characterized in that: The polyimide film is coated by a coating operation, and the coating operation is to transfer the polyimide film by a wet or evaporation process.

8. The method for thinning a fingerprint recognition module as claimed in claim 1, wherein: A light source is used in the process of preparing the thin film transistor array, and the light source does not react with the polyimide film.

9. The method for thinning a fingerprint recognition module as claimed in claim 1, wherein: After the fingerprint identification printed coating is exposed, the transparent substrate is firstly cut by a knife wheel or laser, and then the polyimide film is irradiated with excimer laser light to remove the polyimide film to obtain a plurality of fingerprint identification modules.

10. A method for thinning a fingerprint recognition module, characterized in that: The following steps are involved: Providing a light-transmitting substrate, wherein the light-transmitting substrate has a first surface and a second surface corresponding to each other; forming a polyimide film on the first surface; A carrier is disposed on the polyimide film, wherein the polyimide film and the carrier can protect the first surface and support the thinned transparent substrate; etching and thinning the second surface; Disposing a thin film transistor array on the second surface; Performing fingerprint recognition stack printing on the thin film transistor array; exposing the fingerprint identification stack; irradiating the polyimide film with excimer laser light; The polyimide film and the carrier are removed.

11. The method for thinning a fingerprint recognition module according to claim 10, wherein: After providing the light-transmitting substrate and before forming the polyimide film on the first surface, the step of physically polishing the first surface is performed.

12. The method for thinning a fingerprint recognition module according to claim 10, wherein: After etching and thinning the second surface, before arranging a thin film transistor array on the second surface, a step is performed: physically polishing the second surface.

13. The method for thinning a fingerprint recognition module as claimed in claim 10, characterized in that: After removing the polyimide film, the step of: performing a knife wheel cutting or a laser cutting on the transparent substrate is performed.

14. The method for thinning a fingerprint recognition module as claimed in claim 10, characterized in that: The thin film transistor array includes a silicon oxide layer and a metal layer. The silicon oxide layer is arranged on the second surface, and the metal layer is located on the silicon oxide layer.

15. The method for thinning a fingerprint recognition module according to claim 1 or claim 10, characterized in that: After the thinned fingerprint recognition module is manufactured, a finished product factory inspection is performed, and the thickness of the transparent substrate is measured.

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