REFERENCE TO RELATED APPLICATIONThis Application is based on U.S. Provisional Application Ser. No. 62/425,715, filed 23 Nov. 2016.
BACKGROUND OF THE INVENTIONField of the InventionThe present invention relates to a package structure, particularly to an optical fingerprint sensor package.
Description of the Related ArtTypically, fingerprints have a number of features including ridges, valleys, and finer points. A finer point includes a bifurcation where a ridge is branched and an end point where the ridge ends. The fingerprint can be regarded as a unique biometric data since its characteristic distribution is different every person and two people cannot have the same fingerprints. Thus, the use of biometric data such as fingerprints in a security system may ensure efficient and accurate protection for the district that requires security, movable assets or the like.
A fingerprint recognition apparatus for acquiring an image of the fingerprint may be classified into a semiconductor type apparatus and optical type apparatus, and an optical fingerprint recognition apparatus is widely used rather than a semiconductor fingerprint recognition apparatus. The optical fingerprint recognition apparatus includes light sources, an image sensor and a total internal reflection prism glass in which light proceeds through the incident surface of the prism, is reflected at the contact surface of the prism, and is emitted from the exit surface of the prism. When a finger is put on the contact surface of the prism, light undergoes diffused reflectance at the points where the ridges of the fingerprint are in contact with the glass. However, no light undergoes the diffused reflectance at the points where the valleys of the fingerprint are in contact with the glass. Thus, the light emitted from the exit surface of the prism exhibits the characteristics of the fingerprint. Refer toFIG. 1. The conventional optical fingerprint recognition package includes a supportingbase10, anisolated base12, afirst adhesive14, asecond adhesive16,LEDs18, animage sensor20, and atransparent colloid22. Theisolated base12 is located in the supportingbase10. TheLEDs18 are located on theisolated base12 through thefirst adhesive14. Theimage sensor20 is located on the supportingbase10 through thesecond adhesive16. Thetransparent colloid22 is located in the supportingbase10 to cover theisolated base12, thefirst adhesive14, thesecond adhesive16, theLEDs18, and theimage sensor20. However, due to the existence of the supportingbase10, the whole volume of the conventional optical fingerprint recognition package is larger. As a result, the conventional optical fingerprint recognition package is difficultly embedded in a panel or a glass cover.
To overcome the abovementioned problems, the present invention provides an optical fingerprint sensor package.
SUMMARY OF THE INVENTIONA primary objective of the present invention is to provide an optical fingerprint sensor package, which penetrates a carrier to form a cavity and places an image sensor in the cavity to decrease the thickness and volume of the optical fingerprint sensor package.
To achieve the abovementioned objectives, the present invention provides an optical fingerprint sensor package, which comprises a carrier, an image sensor, at least one LED (light emitting diode), and a molding compound. The carrier is penetrated with a first cavity. The carrier has a peripheral region surrounding the first cavity. The peripheral region is provided with first conductive pads thereon. The image sensor is mounted in the first cavity and electrically connected to the first conductive pads by conductive wire bonding. The LED is mounted to correspond to the peripheral region of the carrier. The molding compound covers the peripheral region of the carrier, the image sensor, and the at least one LED, and fills the first cavity to fix the image sensor in the first cavity and expose the bottom of the image sensor to an external space.
In an embodiment of the present invention, the at least one LED is mounted on the peripheral region of the carrier through an adhesive by surface-mount technology (SMT).
In an embodiment of the present invention, the adhesive is a red glue or a silver paste.
In an embodiment of the present invention, the height of the bottom of the at least one LED is higher than the height of the top of the image sensor.
In an embodiment of the present invention, the peripheral region of the carrier is further provided with second conductive pads thereon and penetrated with at least one second cavity. The at least one LED is mounted in the at least one second cavity of the peripheral region, the molding compound fills the at least one second cavity to fix the at least one LED in the at least one second cavity and expose the bottom of the at least one LED to the external space. The at least one LED is electrically connected to the second conductive pads by conductive wire bonding.
In an embodiment of the present invention, the at least one second cavity further comprises a plurality of second cavities, and the at least one LED further comprises a plurality of LEDs (light emitting diodes) respectively mounted in the plurality of second cavities.
In an embodiment of the present invention, the height of the top of the carrier is higher than the height of the top of the at least one LED.
In an embodiment of the present invention, the carrier is a substrate or a lead frame.
In an embodiment of the present invention, the at least one LED comprises a plurality of LEDs (light emitting diodes).
In an embodiment of the present invention, the at least one LED is an infrared (IR) LED.
In an embodiment of the present invention, the image sensor is a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS).
Below, the embodiments are described in detail in cooperation with the drawings to make easily understood the technical contents, characteristics and accomplishments of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a diagram showing an optical fingerprint sensor package in the conventional technology;
FIG. 2 is a top view of an optical fingerprint sensor package according to the first embodiment of the present invention;
FIG. 3 is a sectional view taken along Line A-A′ ofFIG. 2;
FIG. 4 is a top view of the optical fingerprint sensor package according to the second embodiment of the present invention; and
FIG. 5 is a sectional view taken along Line B-B′ ofFIG. 4.
DETAILED DESCRIPTION OF THE INVENTIONReference will now be made in detail to embodiments illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. In the drawings, the shape and thickness may be exaggerated for clarity and convenience. This description will be directed in particular to elements forming part of, or cooperating more directly with, methods and apparatus in accordance with the present disclosure. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art. Many alternatives and modifications will be apparent to those skilled in the art, once informed by the present disclosure.
Refer toFIG. 2 andFIG. 3. The first embodiment of the optical fingerprint sensor package of the present invention is introduced as follows. The optical fingerprint sensor package comprises acarrier24, animage sensor26, at least one LED (light emitting diode)28, and amolding compound30. For example, thecarrier24 is a substrate or a lead frame, and theLED28 is an infrared (IR) LED, and theimage sensor26 is a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS). Thecarrier24 is penetrated with afirst cavity32. Thecarrier24 has aperipheral region34 surrounding thefirst cavity32. Theperipheral region34 is provided with firstconductive pads36 thereon. Theimage sensor26 is mounted in thefirst cavity32 and electrically connected to the firstconductive pads36 by conductive wire bonding. In the first embodiment, there is a plurality of LEDs (light emitting diodes)28. The plurality ofLEDs28 is mounted to correspond to theperipheral region34 of thecarrier24. In the first embodiment, each of the plurality ofLEDs28 is mounted on theperipheral region34 of thecarrier24 through an adhesive38 by surface-mount technology (SMT). For example, the adhesive38 is a red glue or a silver paste. In order to prevent the side light of eachLED28 from interfering with theimage sensor26, the height of the bottom of eachLED28 is higher than the height of the top of theimage sensor26. Themolding compound30 covers theperipheral region34 of thecarrier24, theimage sensor26, and eachLED28, and fills thefirst cavity32 to fix theimage sensor26 in thefirst cavity32 and expose the bottom of theimage sensor26 to an external space. Thecarrier24 is not provided with any substrate thereunder. The thickness of theimage sensor26 is similar to that of thecarrier24. In addition, the thickness of theLED28 is very thin. As a result, the present invention penetrates the carrier to form the cavity and places the image sensor in the cavity to decrease the thickness and volume of the optical fingerprint sensor package, such that the optical fingerprint sensor package is easily embedded in a thin panel or a thin glass cover.
Refer toFIG. 4 andFIG. 5. The second embodiment of the optical fingerprint sensor package of the present invention is introduced as follows. The optical fingerprint sensor package comprises acarrier24, animage sensor26, at least one LED (light emitting diode)28, and amolding compound30. For example, thecarrier24 is a substrate or a lead frame, and theLED28 is an infrared (IR) LED, and theimage sensor26 is a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS). Thecarrier24 is penetrated with afirst cavity32. Thecarrier24 has aperipheral region34 surrounding thefirst cavity32. Theperipheral region34 is provided with firstconductive pads36 and secondconductive pads40 thereon and penetrated with at least onesecond cavity42. Theimage sensor26 is mounted in thefirst cavity32 and electrically connected to the firstconductive pads36 by conductive wire bonding. In the second embodiment, there are a plurality of LEDs (light emitting diodes)28 and a plurality ofsecond cavities42. The plurality ofLEDs28 is mounted to correspond to theperipheral region34 of thecarrier24. In the second embodiment, the plurality ofLEDs28 is respectively mounted in the plurality ofsecond cavities42 of theperipheral region34. In order to prevent the side light of eachLED28 from interfering with theimage sensor26, the height of the top of thecarrier24 is higher than the height of the top of eachLED28, such that thecarrier24 blocks the side light of eachLED28. The plurality ofLEDs28 is electrically connected to the secondconductive pads40 by conductive wire bonding. Themolding compound30 covers theperipheral region34 of thecarrier24, theimage sensor26, and eachLED28, fills thefirst cavity32 to fix theimage sensor26 in thefirst cavity32 and expose the bottom of theimage sensor26 to an external space, and fills the plurality ofsecond cavities42 to fix the plurality ofLEDs28 in the plurality ofsecond cavities42 and expose the bottom of the plurality ofLEDs28 to the external space. Thecarrier24 is not provided with any substrate thereunder. The thickness of theimage sensor26 is similar to that of thecarrier24. In addition, the thickness of theLED28 is very thin. As a result, the present invention penetrates the carrier to form the cavity and places the image sensor in the cavity to decrease the thickness and volume of the optical fingerprint sensor package, such that the optical fingerprint sensor package is easily embedded in a thin panel or a thin glass cover.
In conclusion, the present invention penetrates the carrier to accommodate the image sensor, thereby reducing the thickness and volume of the optical fingerprint sensor package.
The embodiments described above are only to exemplify the present invention but not to limit the scope of the present invention. Therefore, any equivalent modification or variation according to the shapes, structures, features, or spirit disclosed by the present invention is to be also included within the scope of the present invention.