Fingerprint recognition apparatus

A fingerprint recognition apparatus includes an electrode-and-wiring substrate having two main surfaces opposite to each other, where one main surface is in proximity to user finger and the electrode-and-wiring substrate has a plurality of sensing electrodes on the other main surface. The fingerprint recognition apparatus further includes an integrated circuit (IC) chip having a fingerprint sensing circuit and a plurality of metal bumps. At least part of the metal bumps are electrically connected to the fingerprint sensing circuit and corresponding sensing electrodes on the electrode-and-wiring substrate, whereby the fingerprint sensing circuit is electrically connected to the sensing electrodes.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to fingerprint recognition apparatus, especially to a fingerprint recognition apparatus with high sensitivity.

Description of Related Art

Biometric recognition technologies have rapid development due to the strong request from electronic security applications and automatic access control system. The biometric recognition technologies can be classified into fingerprint recognition, iris recognition, DNA recognition, and so on. For the considerations of efficiency, safety and non-invasiveness, the fingerprint recognition becomes main stream technology. The fingerprint recognition device can scan fingerprint image by optical scanning, thermal imaging or capacitive imaging. For cost, power-saving, reliability and security concerns, the capacitive fingerprint sensor becomes popular for biometric recognition technology applied to portable electronic devices.

The conventional capacitive fingerprint sensors can be classified into swipe type and area type (pressing type), and the area type has better identification correctness, efficiency and convenience. However, the area type capacitive fingerprint sensor generally integrates the sensing electrodes and the sensing circuit into one integrated circuit (IC).FIG. 1Ashows a sectional view of a related art capacitive fingerprint sensor, which comprises a package substrate102A, a fingerprint recognition IC100A and a sapphire protection film140A. The fingerprint recognition IC100A is arranged on the package substrate102A and has a sensing area with a plurality of sensing electrodes110A. The sensing electrodes110A are arranged on a surface of the fingerprint recognition IC100A, which is closer to the user finger. The conductive pads120A of the fingerprint recognition IC100A are electrically connected to the corresponding conductive pads104A on the package substrate102A through the lead-out wires130A. To protect the lead-out wires130A, a sealing resin150A is used to encapsulate the lead-out wires130A. However, the distance between the finger and the sensing electrodes110A will be increased by the height h1(in the order of tens of micro meters), and this has great impact on the sensing accuracy. The area along the height h1needs to be filled with expensive sapphire protection film140A with high dielectric constant. This will increase cost and the extra distance h1renders the capacitive fingerprint sensors difficult to be integrated below the protection glass.

FIG. 1Bis a sectional view of another related art capacitive fingerprint sensor, where the capacitive fingerprint sensor is packaged into an electronic device with a protection glass20A having thickness h2. Due to the protection glass20A, the distance between the finger and the sensing electrodes110A will be increased by the height (h1+h2). A common solution to reduce the distance is to dig hole in the protection glass20A and then embed the fingerprint recognition IC100A into the hole. However, material cost and fabrication complexity are increased while the yield, lifetime and durability of the product are reduced. It is development trend to enhance sensing accuracy and signal-to-noise ratio to advantageously increase the distance between the finger and the sensing electrodes. Moreover, it is desirable to place the fingerprint recognition IC below the protection glass to reduce cost and enhance the lifetime and durability of the products.

It is an object of the present invention to provide a fingerprint recognition apparatus with low cost and high performance. The sensed signals are led out through metal bumps to reduce the sensing distance by tens of micro meter, which is caused by the conventional lead-out wire. The packaging complexity and cost are reduced while the sensing accuracy is enhanced. Another object of the present invention is to provide a fingerprint recognition apparatus with flexible and simple process.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, the present invention provides a fingerprint recognition apparatus, comprising: an electrode-and-wiring substrate having two main surfaces opposite to each other, where one main surface is in proximity to user finger and the electrode-and-wiring substrate has a plurality of sensing electrodes on the other main surface; an integrated circuit (IC) chip having a fingerprint sensing circuit and a plurality of metal bumps, at least part of the metal bumps electrically connected with the fingerprint sensing circuit and corresponding sensing electrodes on the electrode-and-wiring substrate, whereby the fingerprint sensing circuit is electrically connected to the sensing electrodes.

According to another aspect of the present invention, the present invention provides a fingerprint recognition apparatus, comprising: a wiring substrate having two main surfaces opposite to each other, where one main surface is in proximity to user finger and the wiring substrate has a plurality of conductive pads and conductive wires on the other main surface; and an integrated circuit (IC) chip having a fingerprint sensing circuit, a plurality of sensing electrodes and a plurality of metal bumps, the fingerprint sensing circuit electrically connected with the sensing electrodes, wherein the fingerprint sensing circuit is electrically connected with parts of the conductive pads and part of the conductive wires on the wiring substrate, whereby the fingerprint sensing circuit is electrically connected to an external electric circuit.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2is a sectional view of the fingerprint recognition apparatus according to the first embodiment of the present invention, andFIG. 3shows the top view of the fingerprint recognition apparatus according to the first embodiment of the present invention. In the first embodiment, the fingerprint recognition apparatus is, for example, a self-capacitance fingerprint recognition apparatus. The fingerprint recognition apparatus10mainly comprises an electrode-and-wiring substrate100and an integrated circuit (IC) chip300. The electrode-and-wiring substrate100has two main surfaces opposite to each other, where one main surface is in proximity to user finger F and the other main surface has a plurality of sensing electrodes120arranged thereon. The IC chip300is arranged on a substrate302and comprises a fingerprint sensing circuit310and a plurality of metal bumps320electrically connected with the fingerprint sensing circuit310. The metal bumps320are arranged on a surface of the IC chip300, which is away from the substrate302, and the metal bumps320are corresponding to the sensing electrodes120on the electrode-and-wiring substrate100. Moreover, at least part of the metal bumps320may be electrically connected to the corresponding sensing electrodes120on the electrode-and-wiring substrate100through anisotropic conductive film (ACF)322. Moreover, the fingerprint recognition apparatus10further comprises an external circuit board50arranged on the surface of the electrode-and-wiring substrate100, on which the sensing electrodes120are arranged. The external circuit board50may be a flexible printed circuit board or a rigid printed circuit board, and electrically connected with the electrode-and-wiring substrate100through conductive pads52, which will be detailed later.

With reference toFIG. 3, the fingerprint recognition apparatus10is viewed from the finger pointing direction. The sensing electrodes120on the electrode-and-wiring substrate100are arranged, for example, in array manner. An area of each of the metal bumps320is not larger than an area of corresponding one of the sensing electrodes120. Each of the sensing electrodes120is electrically connected with the fingerprint sensing circuit310of the IC chip300through the corresponding metal bumps320. Moreover, the fingerprint sensing circuit310can be selectively connected with the sensing electrodes120through the connection of the metal bumps320and performs self-capacitance fingerprint sensing by sensing the detected signal respectively from the sensing electrodes120. The technique of self-capacitance fingerprint sensing is well known art and is not detailed here for brevity. The metal bumps320can be formed by directly placing tin solder or gold on the electric pads (not shown) of the IC chip300through thin film process, chemical plating process, electrical plating process or printing process, thus providing electric connection mechanism with fine pitch, low inductance, low cost and good thermal dissipation. The metal bumps320are, for example, gold bumps or solder bumps. With reference also toFIG. 2, each of the sensing electrodes120is electrically connected with the corresponding metal bump320through ACF322. With reference again toFIG. 3, the electrode-and-wiring substrate100further comprises a plurality of conductive pads122and a plurality of conductive wires124. At least part of the conductive pads122are electrically connected with the conductive pads52of the external circuit board50and another part of the conductive pads122are electrically connected with the metal bumps320and further electrically connected with the fingerprint sensing circuit310of the IC chip300through the metal bumps320, thus achieving the electric connection between the fingerprint sensing circuit310of the IC chip300and the external circuit board50and transmitting the sensed signal of the fingerprint sensing circuit310out of the IC chip300. Moreover, in the first embodiment shown inFIGS. 2 and 3, the electrode-and-wiring substrate100can be glass substrate (such as protection glass of display apparatus), ceramic substrate, sapphire substrate or polymer film. The thickness of the electrode-and-wiring substrate100can be reduced to several micro meters, which is one order of magnitude less than that of sealing resin150A. The sealing resin150A needs thickness of tens of micro meters to protect the lead-out wires130A. Therefore, the fingerprint recognition apparatus10of the present invention has enhanced measurement sensitivity and lower cost.

FIG. 4shows the top view of the fingerprint recognition apparatus10according to the second embodiment of the present invention. The sectional view of the second embodiment of the present invention can be referred to the structure shown inFIG. 2. More particularly, the fingerprint recognition apparatus10inFIG. 4is viewed from the finger pointing direction and can be used for mutual-capacitance fingerprint sensing. The sensing electrodes on the electrode-and-wiring substrate100includes row sensing electrodes R1˜R6arranged in row by row manner, and column sensing electrodes C1˜C3of stripe shape. Each of the row sensing electrodes R1˜R6comprises a plurality of sensing electrodes120R and the sensing electrodes120R in each of the row sensing electrodes R1˜R6are respectively separated by the column sensing electrodes C1˜C3of stripe shape. Moreover, each of the sensing electrodes120R in the row sensing electrodes R1˜R6is electrically connected to the IC chip300through corresponding metal bump320and the sensing electrodes120R are assigned to respective row by the switch circuit312(seeFIG. 2) in the IC chip300. Moreover, each of the column sensing electrodes C1˜C3is electrically connected to the IC chip300through the corresponding metal bump320. The fingerprint sensing circuit310of the IC chip300sequentially sends signal to the column sensing electrodes C1˜C3and then sequentially receives fingerprint sensed signal from the row sensing electrodes R1˜R6, thus achieving mutual-capacitance fingerprint sensing. Alternatively, the fingerprint sensing circuit310of the IC chip300can also sequentially send signal to the row sensing electrodes R1˜R6and then sequentially receive fingerprint sensed signal from the column sensing electrodes C1˜C3, thus also achieving mutual-capacitance fingerprint sensing. Moreover, even not clearly shown in this figure, the fingerprint recognition apparatus10according to the second embodiment of the present invention may have similar relationship between the electrode-and-wiring substrate100and the IC chip300as that shown inFIG. 2. Namely, the IC chip300also has the substrate302, the fingerprint sensing circuit310and the switch circuit312. The electrode-and-wiring substrate100further comprises a plurality of conductive pads122and a plurality of conductive wires124. At least part of the conductive pads122are electrically connected with the conductive pads52of the external circuit board50and another part of the conductive pads122are electrically connected with the metal bumps320and further electrically connected with the fingerprint sensing circuit310of the IC chip300through the metal bumps320, thus achieving the electric connection between the fingerprint sensing circuit310of the IC chip300and the external circuit board50and transmitting the sensed mutual capacitance signal of the fingerprint sensing circuit310out of the IC chip300.

FIG. 5shows the top view of the fingerprint recognition apparatus10according to the third embodiment of the present invention. The sectional view of the third embodiment of the present invention can be referred to the structure shown inFIG. 2. More particularly, the fingerprint recognition apparatus10inFIG. 5is viewed from the finger pointing direction and can be used for self-capacitance fingerprint sensing or mutual-capacitance fingerprint sensing. The sensing electrodes inFIG. 5is similar to those shown inFIG. 3, namely, the sensing electrodes are arranged in array manner. Therefore, the embodiment shown inFIG. 5can be used for self-capacitance fingerprint sensing. Moreover, the embodiment shown inFIG. 5can also be used for mutual-capacitance fingerprint sensing by following way, namely, grouping the sensing electrodes respectively into row sensing electrodes and column sensing electrodes. The sensing electrodes are selected though the switch circuits312(seeFIG. 2) in the IC chip300to function as row sensing electrodes R1˜R6arranged in individual row, and column sensing electrodes C1˜C3arranged in individual column. As shown inFIG. 5, the switch circuits312in the IC chip300electrically connects the sensing electrodes120R11,120R12,120R13and120R14to constitute the row sensing electrode R1. Similarly, the switch circuits312in the IC chip300electrically connects the sensing electrodes120C11,120C12,120C13,120C14,120C15and120C16to constitute the column sensing electrode C1. The formation of the remaining row sensing electrode R2˜R6and the column sensing electrode C2˜C3can be made in similar manner, and the detailed description is omitted here for brevity. Each of the row sensing electrodes R1˜R6comprises a plurality of sensing electrodes120R and each of the column row sensing electrodes C1˜C3comprises a plurality of sensing electrodes120C. The sensing electrodes120R in each of the row sensing electrodes R1˜R6are respectively separated by the column sensing electrodes C1˜C3arranged column by column, and the sensing electrodes120C in each of the column sensing electrodes C1˜C3are respectively separated by the row sensing electrodes R1˜R6arranged row by row. Similarly, the fingerprint sensing circuit310of the IC chip300sequentially sends signal to the column sensing electrodes C1˜C3and then sequentially receives fingerprint sensed signal from the row sensing electrodes R1˜R6, or vice versa (sequentially sends signal to the row sensing electrodes R1˜R6and then sequentially receives fingerprint sensed signal from the column sensing electrodes C1˜C3), thus achieving mutual-capacitance fingerprint sensing.FIG. 5only depicts an illustrated example, while the number of rows (columns) in the sensing electrodes can be adjusted and not limited to the specific example (3 columns and 6 rows). Moreover, even not clearly shown in this figure, the fingerprint recognition apparatus10according to the third embodiment of the present invention may have similar relationship between the electrode-and-wiring substrate100and the IC chip300as that shown inFIG. 2. Namely, the IC chip300also has the substrate302, the fingerprint sensing circuit310and the switch circuit312. The electrode-and-wiring substrate100further comprises a plurality of conductive pads122and a plurality of conductive wires124. At least part of the conductive pads122are electrically connected with the conductive pads52of the external circuit board50and another part of the conductive pads122are electrically connected with the metal bumps320and further electrically connected with the fingerprint sensing circuit310of the IC chip300through the metal bumps320, thus achieving the electric connection between the fingerprint sensing circuit310of the IC chip300and the external circuit board50and transmitting the sensed mutual capacitance signal of the fingerprint sensing circuit310out of the IC chip300.

FIG. 6shows the top view of the fingerprint recognition apparatus10according to the fourth embodiment of the present invention. The sectional view of the fourth embodiment of the present invention can be referred to the structure shown inFIG. 2. More particularly, the fingerprint recognition apparatus10inFIG. 6is viewed from the finger pointing direction and can be used for mutual-capacitance fingerprint sensing. The fingerprint recognition apparatus10further comprises a plurality of row sensing electrodes R1˜R6of stripe shape on the electrode-and-wiring substrate100. Moreover, the fingerprint recognition apparatus10further comprises an IC chip300below the electrode-and-wiring substrate100. The IC chip300comprises a plurality of column sensing electrodes C1˜C3of stripe shape arranged on the IC chip300, a substrate302and a fingerprint sensing circuit310. From top projection view, the row sensing electrodes R1˜R6and the column sensing electrodes C1˜C3are substantially cross (vertical) to each other and arranged on different planes. The column sensing electrodes C1˜C3on the IC chip300are electrically connected with the fingerprint sensing circuit310. Each of the row sensing electrodes R1˜R6on the electrode-and-wiring substrate100is electrically connected with the underlying fingerprint sensing circuit310through the corresponding metal bump320. Similarly, the fingerprint sensing circuit310of the IC chip300sequentially sends signal to the column sensing electrodes C1˜C3on the IC chip300and then sequentially receives fingerprint sensed signal from the row sensing electrodes R1˜R6arranged on the electrode-and-wiring substrate100, thus achieving mutual-capacitance fingerprint sensing. In this embodiment, part of the sensing electrodes are arranged on the IC chip300, therefore, the number of the metal bumps320can be reduced. Moreover, each of the row sensing electrodes R1˜R6on the electrode-and-wiring substrate100is of stripe shape and is not constituted by an array of sensing electrodes, the number of the metal bumps320can be further reduced. The sensing electrodes depicted inFIG. 6are of stripe shape for illustration and are not to limit the scope of the present invention. For example, each of the sensing electrodes can be constituted by serially-connected rhombic electrodes to increase effective mutual capacitance between row sensing electrodes or between column sensing electrodes. Moreover, each of the sensing electrodes can be constituted by serially-connected electrodes of other shapes to increase effective mutual capacitance between row sensing electrodes or between column sensing electrodes. The electrode-and-wiring substrate100further comprises a plurality of conductive pads122and a plurality of conductive wires124. At least part of the conductive pads122are electrically connected with the conductive pads52of the external circuit board50and another part of the conductive pads122are electrically connected with the metal bumps320and further electrically connected with the fingerprint sensing circuit310of the IC chip300through the metal bumps320, thus achieving the electric connection between the fingerprint sensing circuit310of the IC chip300and the external circuit board50, thus transmitting the sensed mutual capacitance signal of the fingerprint sensing circuit310out of the IC chip300.

FIG. 7is a sectional view of the fingerprint recognition apparatus according to the fifth embodiment of the present invention, and the embodiment shown inFIG. 7is similar to that shown inFIG. 2. However, the external circuit board50shown inFIG. 2is replaced by an electronic device60shown inFIG. 7. The electronic device60can be integrated circuit in COG or COF package. Moreover, even though not particularly illustrating, the top view for the embodiment shown inFIG. 7can be referred to those shown inFIGS. 3 to 6. Therefore, further description regarding the embodiment inFIG. 7is omitted here for brevity. In the embodiments shown inFIGS. 4 to 7, the electrode-and-wiring substrate100can be glass substrate (such as protection glass of display apparatus), ceramic substrate, sapphire substrate or polymer film. The thickness of the electrode-and-wiring substrate100can be reduced to several micro meters, which is one order of magnitude less than that of sealing resin150A. The sealing resin150A needs thickness of tens of micro meters to protect the lead-out wires130A. Therefore, the fingerprint recognition apparatus10of the present invention has enhanced measurement sensitivity and lower cost.

FIG. 8is a sectional view of the fingerprint recognition apparatus according to the sixth embodiment of the present invention, and the embodiment shown inFIG. 8is similar to that shown inFIG. 2. However, the electrode-and-wiring substrate100shown inFIG. 2is replaced by a wiring substrate100′ shown inFIG. 8, and the IC chip300inFIG. 8further comprising sensing electrodes340. The sensing electrodes340can be implemented with the layout as the self-capacitance sensing electrodes shown inFIG. 3, the mutual-capacitance sensing electrodes shown inFIG. 4, or the mutual-capacitance sensing electrodes constituted by grouping a plurality of sensing electrodes as shown inFIG. 5. Similar to those embodiments shown inFIGS. 2-6, the wiring substrate100′ further comprises a plurality of conductive pads122and a plurality of conductive wires124. At least part of the conductive pads122are electrically connected with the conductive pads52of the external circuit board50and another part of the conductive pads122are electrically connected with the metal bumps320and further electrically connected with the fingerprint sensing circuit310of the IC chip300through the metal bumps320, thus achieving the electric connection between the fingerprint sensing circuit310of the IC chip300and the external circuit board50, thus transmitting the sensed self-capacitance signal or mutual-capacitance signal of the fingerprint sensing circuit310out of the IC chip300. Moreover, in the embodiment shown inFIG. 8, the conductive pads122do not cover the top surface of the IC chip from projected view. For balance sake of package, the IC chip300can be optionally provided with balancing metal bumps330, which are away from the conductive pads122having actual electric connection with the metal bumps320. The balancing metal bumps330are only used for providing balance and need not to have actual electric connection with the metal bumps320(for example, the electric connection with the metal bumps320is achieved through ACF322). However, depending on processing requirement, the balancing metal bumps330can also be connected to floating conductive pads122through ACF.

FIG. 9is a sectional view of the fingerprint recognition apparatus according to the seventh embodiment of the present invention, and the embodiment shown inFIG. 9is similar to that shown inFIG. 8. However, the external circuit board50shown inFIG. 8is replaced by an electronic device60shown inFIG. 7. The electronic device60can be integrated circuit in COG or COF package. Moreover, even though not particularly illustrating, the sensing electrodes340can be implemented with the layout as the self-capacitance sensing electrodes shown inFIG. 3, the mutual-capacitance sensing electrodes shown inFIG. 4, the mutual-capacitance sensing electrodes constituted by grouping a plurality of sensing electrodes as shown inFIG. 5. Similar to the embodiment shown inFIG. 8, for balance sake of package, the IC chip300can be optionally provided with balancing metal bumps330, which are away from the conductive pads122with actual electric connection with the metal bumps320. The balancing metal bumps330are only used for providing balance and need not to have actual electric connection with the metal bumps320(for example, the electric connection with the metal bumps320is achieved through ACF322). However, depending on processing requirement, the balancing metal bumps330can also be connected to floating conductive pads122through ACF.

To sum up, the present invention has following advantages:

1. The present invention provides an innovative fingerprint recognition apparatus architecture. At least part of the sensing electrodes on the fingerprint recognition IC chip are moved to another substrate, thus effectively thinning the substrate and enhancing sensibility.

2. The fingerprint recognition IC chip is used with a wiring substrate such that the fingerprint sensing circuit in the fingerprint recognition IC chip can be electrically connected with the external circuit or the external circuit board, thus reducing package cost and enhancing the flexibility of the fingerprint recognition apparatus.

Thus, particular embodiments have been described. Other embodiments are within the scope of the following claims. For example, the actions recited in the claims may be performed in a different order and still achieve desirable results.