WO2017024436A1

WO2017024436A1 - Fingerprint system and method for forming the same

Info

Publication number: WO2017024436A1
Application number: PCT/CN2015/086342
Authority: WO
Inventors: Wei Fang; Hong Zhu; Yan LING
Original assignee: Shanghai Oxi Technology Co., Ltd
Priority date: 2015-08-07
Filing date: 2015-08-07
Publication date: 2017-02-16
Also published as: CN107004119A

Abstract

A fingerprint system and a method for forming the same are provided. The method includes: providing a cover glass (100), wherein the cover glass (100) comprises a first surface (100a) and a second surface (100b) opposite to the first surface (100a); forming a blind hole (110) on the first surface (100a) of the cover glass (100); forming a first glue layer (410) on the first surface (100a) or the second surface (100b) of the cover glass (100), wherein a location of the glue layer (410) corresponds to a location of the blind hole (110); providing a fingerprint module (300); and combining the fingerprint module (300) with the cover glass (100) through the first glue layer (410). The fingerprint system formed by the method has higher accuracy.

Description

FINGERPRINT SYSTEM AND METHOD FOR FORMING THE SAME

TECHNICAL FIELD

The present disclosure generally relates to photoelectric technology, and more particularly, to a fingerprint system and a method for forming the same.

BACKGROUND

A fingerprint in its narrow sense is an impression left by the friction ridges of a human finger. Human fingerprints are detailed, unique, difficult to alter, and durable over the life of an individual, making them suitable as long-term markers of human identity. Therefore, fingerprints may be employed by police or other authorities to identify individuals.

Fingerprint identification is the process of comparing two instances of friction ridge skin impression, from fingers or toes, to determine whether these impressions could have come from the same individual. The fingerprint identification can be automatically carried out by a fingerprint system. In an optical fingerprint system, a light source is used to illuminate a surface of a human finger. The lights reflected from the finger pass through a cover glass to a photo-diode array which captures a visual image of the fingerprint.

However, the conventional fingerprint system has a low sensitivity.

SUMMARY

In one embodiment, a method for forming a fingerprint system is provided. The method may include: providing a cover glass, wherein the cover glass includes a first surface and a second surface opposite to the first surface； forming a blind hole on the first surface of the cover glass； forming a first glue layer on the first surface or the second surface of the cover glass, wherein a location of the glue layer corresponds to a location of the blind hole； providing a fingerprint module； and combining the fingerprint module with the cover glass through the first glue layer.

In some embodiments, the cover glass beneath the blind hole is thinner than the cover glass around the blind hole.

In some embodiments, the thickness of the cover glass beneath the blind hole ranges from 0.1 mm to 0.8 mm.

In some embodiments, the blind hole has a circular shape, a square shape or a track shape.

In some embodiments, an angle between a side wall and a bottom surface of the blind hole is equal to or greater than 90°.

In some embodiments, a chamfering process is employed to chamfer a connection part of a side wall and a bottom surface of the blind hole.

In some embodiments, forming a blind hole on the first surface of the cover glass may include: providing a grinding device, wherein the grinding device has a grilling head； and grinding the first surface of the cover glass to form the blind hole.

In some embodiments, a rotating speed of the grinding device ranges from 30000 rpm to 50000 rpm.

In some embodiments, forming a blind hole on the first surface of the cover glass may include: forming a first anti-etch film and a second anti-etch film on the first surface and the second surface of the cover glass respectively, wherein the first anti-etch film has an opening exposing a part of the first surface； etching the cover glass through the opening to form the blind hole.

In some embodiments, an HF solution is employed to etching the cover glass.

In some embodiments, the fingerprint module may include: a protection layer, wherein the protection layer is combined with the cover glass through the first glue layer； a sensor layer under the protection layer, wherein the sensor layer is adapted for obtaining fingerprint signals and is combined with the protection layer through a second glue layer； a light guide plate under the sensor layer, wherein the light guide plate is combined with the sensor layer through a third glue layer； a light source disposed on one end of the light guide plate, wherein the light guide plate is adapted for guiding lights emitted from the light source towards the sensor layer； and an IC chip which is electrically connected with the sensor layer, wherein the IC chip is adapted for processing the fingerprint signals obtained by the sensor layer.

In some embodiments, the fingerprint module may include: a protection layer, wherein the protection layer is combined with the cover glass through the first glue layer； a sensor layer under the protection layer, wherein the sensor layer is adapted for obtaining fingerprint signals and is combined with the protection layer through a second glue layer； a light source disposed on one end of the sensor layer； and an IC chip which is electrically connected with the sensor layer, wherein the IC chip is adapted for processing the fingerprint signals obtained by the sensor layer.

In some embodiments, the first glue layer is formed on a bottom surface of the blind hole, and a part of the fingerprint module is disposed in the blind hole.

In some embodiments, a concave is formed on the second surface of the cover glass, and a location of the concave corresponds to the position of the blind hole.

In some embodiments, the first glue layer includes UV glue.

In some embodiments, the method further includes: packaging the fingerprint module in a housing structure.

Accordingly, a fingerprint system is also provided. The fingerprint system is formed by the method described above.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several embodiments in accordance with the disclosure and are, therefore, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings.

FIGs. 1-14 schematically illustrate intermediate structural diagrams in a method for forming a fingerprint system according to embodiments of the present disclosure； and

FIG. 15 schematically illustrates a structural diagram of a mobile phone having a fingerprint system according to one embodiment of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the Figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure.

A method for forming a fingerprint system is provided in embodiments of the present disclosure. The method can reduce a thickness of a cover glass at a touch area in the fingerprint system, so that a sensitivity of the fingerprint system can be improved. Steps of the method will be described in detail hereunder.

First, referring to FIG. 1, a cover glass 100 is provided, wherein the cover glass 100 includes a first surface 100a and a second surface 100b opposite to the first surface 100a.

In some embodiments, the cover glass 100 has a thickness ranging from 0.15 mm to 0.9 mm. In some embodiments, the cover glass 100 may be used as a touch screen of a mobile phone, a computer or a fingerprint identification device.

Then, referring to FIG. 2, a blind hole 110 is formed on the first surface 100a of the cover glass 100.

In some embodiments, the blind hole 110 may be formed by a machining process. The machining process will be described hereunder in conjunction with accompanying FIGs. 2-4.

As shown in FIG. 2, a grinding device 200 is provided. The grinding device 200 has a grinding head 210. The grinding head 210 is applied on the first surface 100a of the cover glass 100, and then the grinding head 210 rotates to grind the first surface 100a of the cover glass 100 in order to form the blind hole 110. After the blind hole 110 is formed, a side wall of the blind hole 110 is perpendicular to the first surface 100a of the cover glass 100. In some embodiments, a rotating speed of the grinding head 210 ranges from 30000 rpm to 50000 rpm. It should be noted that, the rotating speed of the grinding head 210 may differ in different implementation, and is not limited herein. For example, the rotating speed of the grinding head 210 may depend on material of the cover glass 100.

In some embodiments, as shown in FIG. 3, the grinding head 210 may have a raised part 211. If this grinding head 210 is employed to form the blind hole 110, a connection part 115 between a side wall of the blind hole 110 and the first surface 100a of the cover glass may have an arcuate structure. The arcuate structure can reduce internal stress of the cover glass 100.

It should be noted that, a size of the grinding head 210 can be determined based on a size of the blind hole 110. For example, as shown in FIG. 4, the size of the grinding head 210 is the same as the size of the blind hole (not labelled) .

In some embodiments, the blind hole 110 may be formed by an etching process. The etching process will be described hereunder in conjunction with accompanying FIG. 5 and FIG. 6.

Referring to FIG. 5, a first anti-etch film 130a is formed on the first surface 100a of the cover glass 100, and a second anti-etch film 130b is formed on the second surface 100b of the cover glass 100. The first anti-etch film 130a has an opening 131 exposing a part of the first surface 100a.

In some embodiments, the first anti-etch film 130a and the second anti-etch film 130b are acid-resistant films. For example, the first anti-etch film 130a and the second anti-etch film 130b may be polyethylene terephthalate (PET) films. Then, a mechanical cutting process may be employed to form the opening 131 in the acid-resistant film. In subsequent steps, the blind hole 110 will be formed at the part exposed by the opening 131.

In other embodiments, the first anti-etch film 130a and the second anti-etch film 130b are photosensitive films. The photosensitive film may be a polymer compound, for example, polymide, epoxy, benzocyclobutene, etc. A photolithography process may be employed to form the opening 131 in the photosensitive film.

Referring to FIG. 6, by employing the photosensitive film with the opening 131 as a mask, the cover glass 100 is etched to form the blind hole 110. In some embodiments, a wet etch process may be employed to form the blind hole 110. For example, the cover glass 100 with the first anti-etch film 130a and the second anti-etch film 130b may be dipped in an HF solution. In other embodiments, a dry etch process is used to form the blind hole 110.

After forming the blind hole 110 on the first surface 100a of the cover glass 100, the cover glass 100 beneath the blind hole 110 is thinner than the cover glass 100 around the blind hole 110. In some embodiments, the thickness of the cover glass 100 beneath the blind hole 110 ranges from 0.1 mm to 0.8 mm. For example, the cover glass 100 beneath the blind hole 110 may have a thickness of 0.2 mm, 0.26 mm, or 0.3 mm. In some embodiments, the blind hole 100 may have a circular shape, a square shape or a track shape in a plan view.

It should be noted that, the blind hole 110 on the first surface 100a of the cover glass 100 may have different structures. In some embodiments, the angle between the side wall and the bottom surface of the blind hole 110 is equal to 90°. In some embodiments, a chamfering process may be employed to chamfer a connection part of a side wall and a bottom surface of the blind hole 110, so that the corner of the blind hole 110 can be smoothed. For example, as shown in FIG. 7 (a) , the connection part of the side wall and the bottom surface of the blind hole 110 has an arcuate structure, or as shown in FIG. 7 (b) , the connection part of the side wall and the bottom surface of the blind hole 110 has a bevel structure. In some embodiments, the angle between the side wall and the bottom surface of the blind hole 110 is greater than 90°. For example, as shown in FIG 7 (c) , the side wall of the blind hole is a bevel surface, and the connection part of the side wall and the bottom surface has an arcuate structure. Because the corner of the blind hole 110 is smoothed in above structures, defects or contaminations generated in the preceding machining process or etching process can be removed, and internal stress of the cover glass 100 can be reduced. Therefore, structure strength of the blind hole 110 can be improved.

Then, after the blind hole 110 is formed on the first surface 100a of the cover glass 100, a first glue layer is formed on the first surface 100a or the second surface 100b of the cover glass 100, wherein a location of the glue layer corresponds to a location of the blind hole 110.

In some embodiments, referring to FIG. 8, the first glue layer 410 is formed on the first surface 100a of the cover glass 100. Specifically, the first glue layer 410 is formed on the bottom surface of the blind hole 110.

In some embodiments, referring to FIG. 9, the first glue layer 410 is formed on the second surface 100b of the cover glass 100. A location of the glue layer 410 corresponds to the blind hole 110.

The first glue layer 410 may includes UV (Ultraviolet Rays) glue, optical tape, double side tape or other optical glues. In some embodiments, a refractive index of the first glue 410 may be equal to or similar to a refractive index of the cover glass 100.

Then, a fingerprint module is provided. A structure diagram of a fingerprint module 300 is illustrated in FIG. 10. As shown in FIG. 10, the fingerprint module 300 includes a protection layer 310, a sensor layer 320, a light guide plate 330, a light source 340 and an IC chip 350.

The protection layer 310 may be combined with the cover glass 100 in subsequent steps. In some embodiments, the protection layer 310 may be a fibre-optic plate. The fibre-optic plate has advantages of high light transmission efficiency, small inter-stage coupling loss, etc. In other embodiments, the protection layer 310 may be a glass layer, a sapphire layer, or a transparent plastic layer.

The sensor layer 320 is disposed under the protection layer 310, and is combined with the protection layer 310 through a second glue layer 420. The sensor layer 320 is adapted for obtaining fingerprint signals. Specifically, the sensor layer includes a plurality of photodiodes. The plurality of photodiodes can receive optical signals transmitted through the protection layer 310, and convert the optical signals to electric signals.

The light guide plate 330 is disposed under the sensor layer 320, and is combined with the sensor layer through a third glue layer 430. The light source 340 is disposed on one end of the light guide plate 330. The light guide plate 330 is adapted for guiding lights emitted from the light source 340 towards the sensor layer 320. In this embodiment, the light source 340 is a light-emitting diode (LED) .

The IC chip 350 is electrically connected with the sensor layer 320, so that the IC chip 350 can obtain and process the fingerprint signals transmitted from the sensor layer 320. In this embodiment, the IC chip 350 is disposed on the sensor layer 320.

In this embodiment, the fingerprint module 300 further includes a Flexible Printed Circuit (FPC) 360. The FPC 360 is disposed under the light guide plate 330, and is combined with the light guide plate 330 through a fourth glue layer 440. The FPC 360 is electrically connected with the sensor layer 320 and/or the IC chip 350. It should be noted that, the second glue layer 420, the third glue layer 430 and the fourth glue layer 440 may be the same as the first glue layer 410, or may be different from the first glue layer 410.

A working principle of the fingerprint module 300 is illustrated in FIG. 11. For simplicity, the IC chip 350 and the FPC 360 are omitted in FIG. 11. Referring to FIG. 11, in a working process, lights emitted from the light source 340 enter the light guide plate 330. The light guide plate 330 can convert the incident lights into an area light source, and guide the incident lights towards the sensor layer 320. The incident lights transmit through the sensor layer 320 and the protection layer 310, and irradiate a finger 380. Because friction ridges of the finger 380 have different heights, reflected lights from the finger 380 may have different intensities. These reflected lights can be detected by the photodiodes in the sensor layer 320. Therefore, fingerprint signals of the finger 380 can be obtained by the sensor layer 320.

In other embodiments, the fingerprint module may have a different structure. As shown in FIG. 12, the fingerprint module 300 includes a protection layer 310, a sensor layer 320, a light source 340, an IC chip 350 and a FPC layer 360. The protection layer 310 may be combined with the cover glass 100 in subsequent steps. The sensor layer 320 is disposed under the protection layer 310, and is combined with the protection layer 310 through a second glue layer 420. The light source 340 is disposed on one end of the sensor layer 320. The FPC 360 is disposed under the sensor layer 320, and is combined with the sensor layer 320 through a third glue layer 430. The IC chip 350 is disposed on the sensor layer 320, and is electrically connected with the sensor layer 320. The IC chip 350 is adapted for processing the fingerprint signals obtained by the sensor layer 320. A difference between the fingerprint module shown in the FIG. 12 and the fingerprint module shown in FIG. 10 is that, the sensor layer 320 in FIG. 12 has a function to guide lights emitted from the light source 340 towards the sensor layer. The working principle of the fingerprint module shown in the FIG. 12 is similar to that of the fingerprint module shown in the FIG. 10, and is not described in detail herein.

Then, the fingerprint module is combined with the cover glass through the first glue layer.

In some embodiments, as shown in FIG. 8, the first glue layer 410 is formed on the first surface 100a of the cover glass 100, and the fingerprint module 300 is also disposed on the first surface 100a of the cover glass 100. Specifically, the first glue layer 410 is formed on the bottom surface of the blind hole 110, and a part of the fingerprint module 300 is disposed in the blind hole. In some embodiments, as shown in FIG. 9, the first glue layer 410 is formed on the second surface 100b of the cover glass 100, and the fingerprint module 300 is also disposed on the second surface 100b of the cover glass 100.

In embodiments of the present disclosure, the first glue layer 410 is used to combine the cover glass 100 and the fingerprint module 300. Because the first glue layer 410 has a same refractive index as the cover glass 100 and the protection layer of the fingerprint module 300, diffusing lights at an interface between the cover glass 100 and the fingerprint module 300 can be reduce. Therefore, an accuracy of the fingerprint system can be improved.

Further, in embodiments of the present disclosure, the cover glass 100 is thinner beneath the blind hole 110 than at other parts. A thickness of glass between the touch area and the fingerprint module 300 can be reduced, so that light scattering in the cover glass 100 can be reduced. Hence, the accuracy of the fingerprint system can be further improved.

In some embodiments, if the first glue layer 410 is formed on the first surface 100a of the cover glass 100, and the fingerprint module 300 is also disposed on the first surface 100a of the cover glass 100, a concave may be formed on the second surface 100b of the cover glass 100, and a location of the concave corresponds to the position of the blind hole.

In one embodiment, as shown in FIG. 13, a concave 120 is formed on the second surface 100b of the cover glass 100, and the concave 120 has an arcuate shape. In another embodiment, as shown in FIG. 14, the concave 120 has a rectangular shape. The concave 120 can further reduce the thickness of glass between the touch area and the fingerprint module 300. Therefore, the accuracy of the fingerprint system can be further improved.

In some embodiments, the concave 120 can be formed by a grinding process or an etching process. The fabrication process is described in above steps for forming the blind hole, and is not described in detail herein. In some embodiments, the blind hole 110 and the concave 120 have different sizes, and are not aligned with each other, so as to improve the structure strength of the cover glass.

At last, the fingerprint module may be packaged in a housing structure.

As shown in FIG. 8, FIG. 9, FIG. 13 or FIG. 14, the housing structure includes a middle housing structure 510 and a back housing structure 520. In some embodiments, the fingerprint module 300 may be packaged in the middle housing structure 510, and is electrically connected with a Printed Circuit Board (PCB) 530. Then, the back housing structure 520 is used to cover the PCB 530 and the fingerprint module 300.

Accordingly, a fingerprint system is also provided. The fingerprint system is formed according to the method described above. The fingerprint system of the present disclosure can be used in a mobile phone, a computer, or a fingerprint identification device.

Referring to FIG. 15, a fingerprint system 20 of the present disclosure is used in a mobile phone 10. For example, the fingerprint system 20 can be used to recognize a user‘s unique fingerprint to unlock the mobile phone 10. A cross-sectional view along the line A-A1 of the fingerprint system 20 in FIG. 15 is shown in FIG. 8, FIG. 9, FIG. 13 or FIG. 14.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims

A method for forming a fingerprint system, comprising:

providing a cover glass, wherein the cover glass comprises a first surface and a second surface opposite to the first surface；

forming a blind hole on the first surface of the cover glass；

forming a first glue layer on the first surface or the second surface of the cover glass, wherein a location of the glue layer corresponds to a location of the blind hole；

providing a fingerprint module； and

combining the fingerprint module with the cover glass through the first glue layer.
The method according to claim 1, wherein the cover glass beneath the blind hole is thinner than the cover glass around the blind hole.
The method according to claim 2, wherein the thickness of the cover glass beneath the blind hole ranges from 0.1 mm to 0.8 mm.
The method according to claim 1, wherein the blind hole has a circular shape, a square shape or a track shape.
The method according to claim 1, wherein an angle between a side wall and a bottom surface of the blind hole is equal to or greater than 90°.
The method according to claim 1, wherein a chamfering process is employed to chamfer a connection part of a side wall and a bottom surface of the blind hole.
The method according to claim 1, wherein forming a blind hole on the first surface of the cover glass comprises:

providing a grinding device, wherein the grinding device has a grilling head； and grinding the first surface of the cover glass to form the blind hole.
The method according to claim 7, wherein a rotating speed of the grinding device ranges from 30000 rpm to 50000 rpm.
The method according to claim 1, wherein forming a blind hole on the first surface of the cover glass comprises:

forming a first anti-etch film and a second anti-etch film on the first surface and the second surface of the cover glass respectively, wherein the first anti-etch film has an opening exposing a part of the first surface；

etching the cover glass through the opening to form the blind hole.
The method according to claim 9, wherein an HF solution is employed to etching the cover glass.
The method according to claim 1, wherein the fingerprint module comprises:

a protection layer, wherein the protection layer is combined with the cover glass through the first glue layer；

a sensor layer under the protection layer, wherein the sensor layer is adapted for obtaining fingerprint signals and is combined with the protection layer through a second glue layer；

a light guide plate under the sensor layer, wherein the light guide plate is combined with the sensor layer through a third glue layer；

a light source disposed on one end of the light guide plate, wherein the light guide plate is adapted for guiding lights emitted from the light source towards the sensor layer； and

an IC chip which is electrically connected with the sensor layer, wherein the IC chip is adapted for processing the fingerprint signals obtained by the sensor layer.
The method according to claim 1, wherein the fingerprint module comprises:

a protection layer, wherein the protection layer is combined with the cover glass through the first glue layer；

a sensor layer under the protection layer, wherein the sensor layer is adapted for obtaining fingerprint signals and is combined with the protection layer through a second glue layer；

a light source disposed on one end of the sensor layer； and

an IC chip which is electrically connected with the sensor layer, wherein the IC chip is adapted for processing the fingerprint signals obtained by the sensor layer.
The method according to claim 1, wherein the first glue layer is formed on a bottom surface of the blind hole, and a part of the fingerprint module is disposed in the blind hole.
The method according to claim 13, wherein a concave is formed on the second surface of the cover glass, and a location of the concave corresponds to the position of the blind hole.
The method according to claim 1, wherein the first glue layer comprises UV glue.
The method according to claim 1, further comprising: packaging the fingerprint module in a housing structure.
A fingerprint system, wherein the fingerprint system is formed according to any one of claims 1-16.