WO2017070863A1

WO2017070863A1 - Fingerprint imaging system and method for forming the same

Info

Publication number: WO2017070863A1
Application number: PCT/CN2015/093069
Authority: WO
Inventors: Yan LING; Hong Zhu
Original assignee: Shanghai Oxi Technology Co., Ltd
Priority date: 2015-10-28
Filing date: 2015-10-28
Publication date: 2017-05-04

Abstract

A fingerprint imaging system and a method for forming the same are provided. The fingerprint imaging system includes: a sensor including a first surface and a second surface opposite to the first surface, wherein a plurality of first bonding pads are disposed on the first surface of the sensor; a connection board including a third surface and a fourth surface opposite to the third surface, wherein a plurality of second bonding pads are disposed on the third surface of the connection board, and the third surface of the connection board is disposed in a same direction as the first surface of the sensor; and a plurality of bonding wires adapted for connecting the plurality of first bonding pads with the plurality of second bonding pads. Accordingly, the fingerprint imaging system is more compact.

Description

FINGERPRINT IMAGING SYSTEM AND METHOD FOR FORMING THE SAME

TECHNICAL FIELD

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

BACKGROUND

Fingerprint recognition technology can be used for personal identification or verification. Specifically, in a fingerprint recognition system, fingerprint images are captured by a fingerprint sensor. Thereafter, a matching process between the fingerprint images captured and templates stored in the system is performed, so as to determine if they are matching or not. Since the fingerprint recognition technology is kindly to user and fingerprint is distinctive, the fingerprint recognition technology is widely used in various applications, such as personal identification in policeman stations, physical access control in buildings, device access control in personal computers or mobile phones, and so on.

Referring to FIG. 1, a structure diagram of an existing fingerprint module is illustrated. A light guide plate 112 is used to guide lights from a light source 114 to illuminate a surface of a cover layer 130 touched by a finger 150. When a finger 150 touches the cover layer 130, light emitted from the light guide plate 112 penetrates through the sensor 111 and the cover layer 130, and reaches an interface between the finger 150 and the cover layer 130. In microscope view, a part of the interface is made by the cover layer 130 and the ridge of the finger 150, while the other part is made by the cover layer 130 and the air. Due to the difference of the index of refraction between the air and the epidermis of the finger 150, the reflection ratios of the light at the two parts of the interface will be different. The reflected light penetrates through the cover layer 130 and reaches the sensor 111. The sensor 111 which is manufactured based on amorphous silicon TFT (Thin Film Transistor) or LTPS (Low Temperature Poly Silicon) TFT technology on a glass substrate, including an array of pixels (not shown, e.g., photodiode or transistor) , implements photo-electronic conversion to the received reflected light. Thus, electronic signals proportional to the intensity of the reflected light are obtained, based on which a fingerprint image of the finger 150 can be generated. Then the electronic signals are processed by a readout Integrated Circuit (IC) chip 113, and are transmitted to a connection board 120. Generally, the connection board 120 is a Flexible Printed Circuit (FPC) , and is bonded onto the sensor 111 by an FOG (FPC On Glass) process. For example, a plurality of bonding pads (not shown) are formed on the sensor 111 and the connection board 120, where the top surface of the bonding pads is made of Indium Tin Oxide (ITO) . Then an Anisotropic Conductive Film (ACF) 140 is used to connect the bonding pads on the connection board 140 with those on the sensor 111.

However, because the ACF’s conductivity is much lower than that of metal, the bonding pads are designed as large as possible in order to reduce a connection resistance between the sensor 111 and the connection board 120, for example, 100μm～1000μm, which results in a relatively large size of the fingerprint sensor.

SUMMARY

In one embodiment, a fingerprint imaging system is provided. The fingerprint imaging system may include: a sensor including a first surface and a second surface opposite to the first surface, wherein a plurality of first bonding pads are disposed on the first surface of the sensor； a connection board including a third surface and a fourth surface opposite to the third surface, wherein a plurality of second bonding pads are disposed on the third surface of the connection board, and the third surface of the connection board is disposed in a same direction as the first surface of the sensor； and a plurality of bonding wires adapted for connecting the plurality of first bonding pads with the plurality of second bonding pads.

In some embodiments, the plurality of first bonding pads, the plurality of second bonding pads, and the plurality of bonding wires include aluminum, copper, silver or gold material.

In some embodiments, the fingerprint imaging system further includes: a cover layer disposed on the first surface of the sensor, wherein the cover layer exposes the plurality of first bonding pads.

In some embodiments, the fingerprint imaging system further includes: an IC chip adapted for processing electronic signals obtained by the sensor, wherein the IC chip is bonded to the first surface of the sensor, and the IC chip and the plurality of first bonding pads are disposed on two opposite sides of the cover layer.

In some embodiments, the fingerprint imaging system further includes: an IC chip adapted for processing electronic signals obtained by the sensor, wherein the IC chip is disposed on the third surface or the fourth surface of the connection board.

In some embodiments, the connection board is a FPC or a PCB (Printed Circuit Board) .

In some embodiments, the fingerprint imaging system further includes: a substrate, wherein at least a part of the second surface of the sensor and at least a part of the fourth surface of the connection board are attached to a top surface of the substrate.

In some embodiments, at least a part of the second surface of the sensor is attached to the third surface of the connection board.

In some embodiments, a groove is formed on the third surface of the connection board, and at least a part of the sensor is disposed in the groove.

In some embodiments, the sensor is an optical sensor, and the fingerprint imaging system further includes: a light guide plate attached to the second surface of the sensor, and a light source disposed on one end of the light guide plate.

In some embodiments, the fingerprint imaging system further includes: a substrate, wherein at least a part of a bottom surface of the light guide plate and at least a part of the fourth surface of the connection board are attached to a top surface of the substrate.

In some embodiments, at least a part of a bottom surface of the light guide plate is attached to the third surface of the connection board.

In some embodiments, a groove is formed on the third surface of the connection board, and at least a part of the light guide plate is disposed in the groove.

In some embodiments, the fingerprint imaging system further includes: a seal layer, wherein the seal layer seals the plurality of bonding wires, the plurality of first bonding pads and the plurality of second bonding pads.

In some embodiments, the fingerprint imaging system further includes: a housing structure, wherein the housing structure cases the sensor, the plurality of bonding wires and a part of the connection board.

Correspondingly, a method for forming the fingerprint imaging system described above is also provided in embodiments of the present disclosure. In one embodiment, the method includes: providing a sensor, wherein the sensor includes a first surface and a second surface opposite to the first surface, and a plurality of first bonding pads are disposed on the first surface of the sensor； providing a connection board, wherein the connection board includes a third surface and a fourth surface opposite to the third surface, the third surface of the connection board is disposed in a same direction as the first surface of the sensor, and a plurality of second bonding pads are disposed on the third surface of the connection board； and employing a plurality of bonding wires to connect the plurality of first bonding pads with the plurality of second bonding pads.

In some embodiments, the method further includes: forming a cover layer on the first surface of the sensor, wherein the cover layer exposes the plurality of first bonding pads.

In some embodiments, the method further includes: providing a substrate, and attaching at least a part of the second surface of the sensor and at least a part of the fourth surface of the connection board to a top surface of the substrate.

In some embodiments, the method further includes: attaching at least a part of the second surface of the sensor to the third surface of the connection board.

In some embodiments, the method further includes: forming a groove on the third surface of the connection board, and disposing at least a part of the sensor in the groove.

In some embodiments, the sensor is an optical sensor, a light guide plate is attached to the second surface of the sensor, and a light source is disposed on one end of the light guide plate.

In some embodiments, the method further includes: providing a substrate, and attaching at least a part of a bottom surface of the light guide plate and at least a part of the fourth surface of the connection board to a top surface of the substrate.

In some embodiments, the method further includes: attaching at least a part of a bottom surface of the light guide plate to the third surface of the connection board.

In some embodiments, the method further includes: forming a groove on the third surface of the connection board, and disposing at least a part of the light guide plate in the groove.

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.

FIG. 1 schematically illustrates a conventional fingerprint imaging system；

FIG. 2 schematically illustrates a top view of a fingerprint imaging system according to one embodiment of the present disclosure；

FIG. 3 schematically illustrates a cross-sectional view of the fingerprint imaging system shown in FIG. 2；

FIG. 4 is a partial enlarged view of the fingerprint imaging system shown in FIG. 3；

FIG. 5 schematically illustrates a structure diagram of a fingerprint imaging system according to another embodiment of the present disclosure；

FIG. 6 schematically illustrates a structure diagram of a fingerprint imaging system according to another embodiment of the present disclosure；

FIGs. 7-9 schematically illustrate structure diagrams of a fingerprint imaging system with different configurations according to different embodiments of the present disclosure；

FIG. 10 schematically illustrates a cross-sectional view of a fingerprint imaging system according to one embodiment of the present disclosure； and

FIG. 11 schematically illustrates a cross-sectional view of a fingerprint imaging system according to another 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 fingerprint imaging system and a method for forming the same are provided in embodiments of the present disclosure. The embodiments will be described in detail in conjunction with the accompanying drawings.

Referring to FIGs. 2-4, FIG. 2 illustrates a top view of a fingerprint imaging system according to one embodiment of the present disclosure, FIG. 3 illustrates a cross-sectional view of the fingerprint imaging system shown in FIG. 2, and FIG. 4 illustrates a partial enlarged view of FIG. 3.

Specifically, the fingerprint imaging system includes a sensor 211, a connection board 220 and a plurality of bonding wires 230. The sensor 211 includes a first surface 211 a and a second surface 211 b, and a plurality of first bonding pads 215 are disposed on the first surface 211 a of the sensor 211. The connection board 220 includes a third surface 220a and a fourth surface 220b, a plurality of second bonding pads 225 are disposed on the third surface 220a of the connection board 220, and the third surface 220a of the connection board 220 is disposed in a same direction as the first surface 211 a of the sensor 211. The plurality of bonding wires 230 are adapted for connecting the plurality of first bonding pads 215 with the plurality of second bonding pads 225.

In some embodiments, the plurality of first bonding pads 215, the plurality of second bonding pads 225 and the plurality of bonding wires 230 include aluminum, copper, silver or gold material. In other embodiments, the plurality of first bonding pads 215, the plurality of second bonding pads 225 and the plurality of bonding wires 230 also can be made of other metals.

Because metal has a much higher conductivity than ACF material, the connection resistance between the sensor 211 and the connection board 220 can be reduced. Hence, there is no need to form large bonding pads for the fingerprint imaging system of the present disclosure. Compared with the conventional ones, the fingerprint imaging system of the present disclosure can obtain a smaller size.

Specifically, the sensor 211 is adapted for obtaining fingerprint image signals. In some embodiments, a plurality of sensing devices and circuits may be formed on the first surface 211 a of the sensor 211. The plurality of sensing devices and circuits may be formed by an amorphous silicon TFT technology, or a LTPS TFT technology. The plurality of first bonding pads 215 are disposed on an end portion of the first surface 211 a of the sensor 211, and are connected to the plurality of sensing devices and circuits.

In some embodiments, the sensor 211 may be an optical sensor, and a plurality of photodiodes are formed in the sensor 211. The plurality of photodiodes can receive optical signals reflected from the interface between the touching finger 150 and the cover layer 130, and convert the optical signals to electronic signals. The fingerprint imaging sensor further includes a light guide plate 216 and a light source 217 disposed on one end of the light guide plate 216. A top surface of the light guide plate 216 is attached to the second surface 211 b of the sensor 211 through a glue layer. The light guide plate 216 is adapted for guiding lights emitted from the light source 217 towards the human finger 250. In some embodiments, as shown in FIG. 3, the light source 217 is attached to the fourth surface 220b of the connection board 220, wherein the fourth surface 220b of the connection board 220 is opposite to the third surface 220a having the plurality of second bonding pads 225. In some embodiments, the light source 217 may be a LED (light-emitting diode) .

In other embodiments, the sensor 211 may be a capacitance sensor. The sensor 211 can obtain a fingerprint image by detecting the difference of the coupling capacitance between the pixels in the sensor 211 and the epidermis or dermis of the human finger 250.

As shown in FIG. 2 and FIG. 3, the finger imaging system further includes a cover layer 213 and an IC chip 214.

Specifically, the cover layer 213 is disposed on the first surface 211 a of the sensor 211. The cover layer 213 is used for protecting the sensor 211 from scratching or ESD damage. A bottom surface of the cover layer 213 may be attached to the first surface 211 a of the sensor 211, and a top surface of the cover layer 213 is used for finger touching. In a working process of an optical sensor, the finger 250 touches the cover layer 213, then the sensor 211 can capture lights reflected from the interface between the touching finger 150 and the cover layer 130. Hence the cover layer 213 should be made of non-opaque material. In some embodiments, the cover layer 213 may be a fibre-optic plate. The fibre-optic plate contains many optical fibers, which are used to carry light and does not degrade the contrast of the fingerprint image. In other embodiments, the cover layer 213 may be a sapphire layer, a glass layer, a plastic layer, an PET (Polyethylene Terephthalate) layer, a rubber layer or a resin layer, which will degrade the contrast of the fingerprint image.

The IC chip 214 is disposed on the first surface 211 a of the sensor 211. The IC chip 214 is coupled to the sensor 211, so that the IC chip 214 can obtain and process the fingerprint image signals transmitted from the sensor 211. In some embodiments, the IC chip 214 may be bonded on the first surface 211 a of the sensor 211 by a Chip on Glass (COG) process. For example, an ACF layer may be used between the IC chip 214 and the first surface 211 a the sensor 211 for bonding them together.

In some embodiments, as shown in FIG. 2, the IC chip 214 and the plurality of first bonding pads 215 are disposed on a same side of the cover layer 213. In some embodiments, as shown in FIG. 5, the IC chip 214 and the plurality of first bonding pads 215 are disposed on two opposite sides of the cover layer 213. Compared with FIG. 2, the fingerprint imaging system shown in FIG. 5 can obtain a more compact size. In some embodiments, as shown in FIG. 6, the IC chip 214 can also be disposed on the connection board 220.

The connection board 220 is adapted for transmitting electronic signals between the sensor 211 and an external system. For example, the fingerprint imaging system can be used in a mobile phone, a computer, or a fingerprint identification system, and the external system may be a subsystem thereof. As shown in FIG. 3, there may be a plurality of other IC components 221 and connectors 223 formed on the fourth surface 220b of the connection board 220. The connectors 223 may be bonding pads, and can be used to connect with the external system.

In some embodiments, the connection board 220 may be a FPC. The FPC consists of a thin insulating polymer film having conductive circuit patterns affixed thereto, and is typically supplied with a thin polymer coating to protect the conductor circuits. Referring to FIG. 7, because the FPC is flexible, the fingerprint imaging system may further include a rigid substrate 260 for supporting the sensor 211 and the connection board 220. For example, at least a part of the second surface 211 b of the sensor 211 and at least a part of the fourth surface 220b of the connection board 220 are attached to a top surface of the substrate 260.

In some embodiments, the connection board 220 may be a PCB. The PCB can serve as a mechanical support for the sensor 211. Referring to FIG. 8, in one embodiment, at least a part of the second surface 211 b of the sensor 211 is attached to the third surface 220a of the connection board 220. However, if the sensor 211 is disposed on the connection board 220, the plurality of first bonding pads 215 on the sensor 211 and the plurality of second bonding pads 225 may be at different levels, which may complicate a wire bonding process for connecting the plurality of first bonding pads 215 with the plurality of second bonding pads 225.

In order to solve the above problem, in some embodiments, a groove can be formed on the third surface 220a of the connection board 220. Referring to FIG. 9, by forming a groove 270 on the third surface 220a of the connection board 220, the sensor 211 can be disposed in the groove 270, such that the plurality of first bonding pads 215 on the sensor 211 and the plurality of second bonding pads 225 could be disposed at a same level.

It should be noted that, for simplicity, some components of the fingerprint system are omitted in FIG. 7, FIG. 8 and FIG. 9, for example, the cover layer 213 and the IC chip 214.

It also should be noted that, if the sensor 211 is an optical sensor, the fingerprint system further includes a light guide plate and a light source. In some embodiments, similarly to the structure shown in FIG. 7, at least a part of the a bottom surface of the light guide plate and at least a part of the fourth surface 220b of the connection board 220 are attached to the top surface of the substrate 260. In some embodiments, similarly to the structure shown in FIG. 8, at least a part of a bottom surface of the light guide plate is attached to the third surface 220a of the connection board 220. In some embodiments, similarly to the structure shown in FIG. 9, a groove 270 is formed on the third surface 220a of the connection board 200, and at least a part of the light guide plate is disposed in the groove 270.

In some embodiments, referring to FIG. 10, the fingerprint imaging system further includes a seal layer 280. The seal layer 280 seals the plurality of bonding wires 230, the plurality of first bonding pads 215 and the plurality of second bonding pads 225, and covers a part of the first surface 211 a of the sensor 211 and a part of the third surface 220a of the connection board 220. In some embodiments, the seal layer 280 may be made of a type of glue which is insulating.

In some embodiments, referring to FIG. 11, the fingerprint imaging system further includes a housing structure 290. The housing structure 290 cases the sense 211, the plurality of bonding wires 230 and a part of the connection board 220 to protect them from pollution and damage. However, the housing structure 290 exposes a top surface of the cover layer 213, thus that a finger can touch the top surface of the cover layer 213. In some embodiments, the housing structure 290 is made of glue, metal, plastic, glass, rubber or resin.

In some embodiments, the fingerprint imaging system may include both the seal layer 280 and the housing structure 290. The housing structure 290 has a hollow part, and the seal layer 280 is disposed in the hollow part.

Accordingly, a method for forming the fingerprint imaging system described above is also provided in embodiments of the present disclosure. Referring to FIG. 10 and FIG. 11, the method includes: providing a sensor 211, wherein the sensor 211 includes a first surface 211 a and a second surface 211 b opposite to the first surface 211 a, and a plurality of first bonding pads 215 are disposed on the first surface 211 a of the sensor 211； providing a connection board 220, wherein the connection board 220 includes a third surface 220a and a fourth surface 220b opposite to the third surface 220a, the third surface 220a of the connection board 220 is disposed in a same direction as the first surface 211 a of the sensor 211, and a plurality of second bonding pads 225 are disposed on the third surface 220b of the connection board 220； and employing a plurality of bonding wires 230 to electrically connect the plurality of first bonding pads 215 with the plurality of second bonding pads 225. In some embodiments, the method further includes forming a cover layer 213 on the first surface 211 a of the sensor 211, wherein the cover layer 213 exposes the plurality of first bonding pads 215.

It should be noted that, the order of the steps for forming the fingerprint imaging system is not limited in this disclosure, and may be different in specific implementations. For example, in some embodiments, the step of forming the cover layer 213 on the first surface 211 a of the sensor 211 may be performed before the step of employing the plurality of bonding wires 230 to electrically connect the plurality of first bonding pads 215 with the plurality of second bonding pads 225.

For simplicity, the sensor 211 and the connection board 220 will not described in detail herein. For more details, please refer to the fingerprint imaging system described above.

Referring to FIG. 7, if the connection board 220 is a FPC, the method further includes: providing a substrate 260, and attaching at least a part of the second surface 211 b of the sensor 211 and at least a part of the fourth surface 220b of the connection board 220 to a top surface of the substrate 260. For example, an adhesive layer (not shown) may be used to adhere at least the second surface 211 b of the sensor 211 and the fourth surface 220b of the connection board 220 onto the top surface of the substrate 260. The adhesive layer may be light sensitive glue, thermosetting glue, optical tape, double side tape or pressure sensitive glue.

Referring to FIG. 8, if the connection board 220 is a PCB, the method further includes: attaching at least a part of the second surface 211 b of the sensor 211 to the third surface 220a of the connection board 220. Similarly, the second surface 211 b of the sensor 211 may be adhered to the third surface 220a of the connection board 220 by an adhesive layer.

In some embodiments, as shown in FIG. 9, the method further includes: forming a groove 270 on the third surface 220a of the connection board 220, and disposing at least a part of the sensor 211 in the groove 270. The groove 270 can be formed by a grinding process or an etching process, and a depth of the groove 270 can be determined according to a thickness of the sensor 211.

If the sensor 211 is an optical sensor, the method further includes forming a light guide plate and a light source, where the light guide plate is below the sensor 211 and the light source is disposed on one end of the light guide plate. In some embodiments, similarly to FIG. 7, the method further includes: providing a substrate 260, and attaching at least a part of a bottom surface of the light guide plate and at least a part of the fourth surface 220b of the connection board 220 to a top surface of the substrate 260. In some embodiments, similarly to FIG. 8, the method further includes: attaching at least a part of a bottom surface of the light guide plate to the third surface 220a of the connection board 220. In some embodiments, similarly to FIG. 8, forming a groove 270 on the third surface 220a of the connection board 220, and disposing at least a part of the sensor 211 in the groove 270.

In a wire bonding process for connecting the plurality of first bonding pads 215 with the plurality of second bonding pads 225, two ends of each bonding wire 230 are attached to one of the plurality of first bonding pads 215 and one of the plurality of second bonding pads 225 respectively, then some combination of heat, pressure and ultrasonic energy are employed to make a weld. Therefore, the plurality of first bonding pads 215 and the plurality of second bonding wires 225 are electrically connected through the plurality of bonding wires 230.

In some embodiments, referring to FIG. 10, a seal layer 280 may be formed to seals the plurality of bonding wires 230, the plurality of first bonding pads 215 and the plurality of second bonding pads 225, and covers a part of the first surface 211 a of the sensor 211 and a part of the third surface 220a of the connection board 220. In some embodiments, referring to FIG. 11, a housing structure 290 may be formed to case the sensor 211, the plurality of bonding wires 230 and a part of the connection board 220. In some embodiments, a glue packaging process or a molding packaging process may be employed to form the housing structure 290.

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 fingerprint imaging system, comprising:

a sensor comprising a first surface and a second surface opposite to the first surface, wherein a plurality of first bonding pads are disposed on the first surface of the sensor；

a connection board comprising a third surface and a fourth surface opposite to the third surface, wherein a plurality of second bonding pads are disposed on the third surface of the connection board, and the third surface of the connection board is disposed in a same direction as the first surface of the sensor； and

a plurality of bonding wires adapted for connecting the plurality of first bonding pads with the plurality of second bonding pads.
The fingerprint imaging system according to claim 1, wherein the plurality of first bonding pads, the plurality of second bonding pads, and the plurality of bonding wires comprise aluminum, copper, silver or gold material.
The fingerprint imaging system according to claim 2, further comprising: a cover layer disposed on the first surface of the sensor, wherein the cover layer exposes the plurality of first bonding pads.
The fingerprint imaging system according to claim 3, further comprising: an Integrated Circuit (IC) chip adapted for processing electronic signals obtained by the sensor, wherein the IC chip is bonded to the first surface of the sensor, and the IC chip and the plurality of first bonding pads are disposed on two opposite sides of the cover layer.
The fingerprint imaging system according to claim 3, further comprising: an IC chip adapted for processing electronic signals obtained by the sensor, wherein the IC chip is disposed on the third surface or the fourth surface of the connection board.
The fingerprint imaging system according to any one of claims 1-5, wherein the connection board is a Flexible Printed Circuit (FPC) or a Printed Circuit Board (PCB) .
The fingerprint imaging system according to claim 6, further comprising: a substrate, wherein at least a part of the second surface of the sensor and at least a part of the fourth surface of the connection board are attached to a top surface of the substrate.
The fingerprint imaging system according to claim 6, wherein at least a part of the second surface of the sensor is attached to the third surface of the connection board.
The fingerprint imaging system according to claim 6, wherein a groove is formed on the third surface of the connection board, and at least a part of the sensor is disposed in the groove.
The fingerprint imaging system according to claim 6, wherein the sensor is an optical sensor, and

wherein the fingerprint imaging system further comprises: a light guide plate attached to the second surface of the sensor, and a light source disposed on one end of the light guide plate.
The fingerprint imaging system according to claim 10, further comprising: a substrate, wherein at least a part of a bottom surface of the light guide plate and at least a part of the fourth surface of the connection board are attached to a top surface of the substrate.
The fingerprint imaging system according to claim 10, wherein at least a part of a bottom surface of the light guide plate is attached to the third surface of the connection board.
The fingerprint imaging system according to claim 10, wherein a groove is formed on the third surface of the connection board, and at least a part of the light guide plate is disposed in the groove.
The fingerprint imaging system according to any one of claims 1-13, further comprising: a seal layer, wherein the seal layer seals the plurality of bonding wires, the plurality of first bonding pads and the plurality of second bonding pads.
The fingerprint imaging system according to any one of claims 1-13, further comprising: a housing structure, wherein the housing structure cases the sensor, the plurality of bonding wires and a part of the connection board.
A method for forming a fingerprint imaging system, comprising:

providing a sensor, wherein the sensor comprises a first surface and a second surface opposite to the first surface, and a plurality of first bonding pads are disposed on the first surface of the sensor；

providing a connection board, wherein the connection board comprises a third surface and a fourth surface opposite to the third surface, the third surface of the connection board is disposed in a same direction as the first surface of the sensor, and a plurality of second bonding pads are disposed on the third surface of the connection board； and

employing a plurality of bonding wires to connect the plurality of first bonding pads with the plurality of second bonding pads.
The method according to claim 16, further comprising: forming a cover layer on the first surface of the sensor, wherein the cover layer exposes the plurality of first bonding pads.
The method according to claim 17, further comprising: providing a substrate, and attaching at least a part of the second surface of the sensor and at least a part of the fourth surface of the connection board to a top surface of the substrate.
The method according to claim 17, further comprising: attaching at least a part of the second surface of the sensor to the third surface of the connection board.
The method according to claim 17, further comprising: forming a groove on the third surface of the connection board, and disposing at least a part of the sensor in the groove.
The method according to claim 16, wherein the sensor is an optical sensor, a light guide plate is attached to the second surface of the sensor, and a light source is disposed on one end of the light guide plate.
The method according to claim 21, further comprising: providing a substrate, and attaching at least a part of a bottom surface of the light guide plate and at least a part of the fourth surface of the connection board to a top surface of the substrate.
The method according to claim 21, further comprising: attaching at least a part of a bottom surface of the light guide plate to the third surface of the connection board.
The method according to claim 21, further comprising: forming a groove on the third surface of the connection board, and disposing at least a part of the light guide plate in the groove.