OPTICAL FINGERPRINT SENSOR PACKAGE

• US 20170083745A1
• Filed: 09/19/2016
• Published: 03/23/2017
• Est. Priority Date: 09/18/2015
• Status: Active Grant

• Current Assignee: Beijing Jiiov Technology Company Limited
• Original Assignee: Synaptics Incorporated
• Inventors: Goodelle, Jason, Wickboldt, Paul, LEE, Young Seen, Lam, Chien, Mackey, Bob Lee
• Granted Patent: US 10,185,866 B2
• Time in Patent Office: Days
• CPC Class Codes: G06V 40/1318 using electro-optical elements or layers, e.g. electroluminescent sensing
• CPC Class Codes: G06V 40/1329 Protecting the fingerprint sensor against damage caused by the finger
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/181 Encapsulation

Abstract

Disclosed are optical sensors, optical fingerprint sensor packages, and methods for forming same. An optical sensor comprises: a substrate; an image sensor disposed over the substrate; a light source disposed over the substrate; a light guide disposed over the image sensor; and, an encapsulant disposed over the light source, wherein the encapsulant is coupled to the light guide and comprises a surface positioned to reflect light emitted from the light source and direct the reflected light into the light guide.

Claims

1. An optical sensor, comprising:

a substrate;

an image sensor disposed over the substrate;

a light source disposed over the substrate;

a light guide disposed over the image sensor; and

an encapsulant disposed over the light source, wherein the encapsulant is coupled to the light guide and comprises a surface positioned to reflect light emitted from the light source and direct the reflected light into the light guide.

2. The optical sensor of claim 1, wherein the substrate comprises a package substrate having electrical interconnections, wherein the image sensor is electrically connected to the package substrate, and wherein the light source is electrically connected to the package substrate.

3. The optical sensor of claim 1, wherein the image sensor comprises a photodetector array.

4. The optical sensor of claim 1, wherein the image sensor comprises a semiconductor die attached to the substrate.

5. The optical sensor of claim 1, wherein the image sensor is disposed over a first area of the substrate, and wherein the light source is disposed over a second area of the substrate outside of the first area of the substrate.

6. The optical sensor of claim 1, wherein the light source comprises a light-emitting diode (LED) attached to the substrate.

7. The optical sensor of claim 1, wherein the light source comprises a plurality of light-emitting diodes (LEDs) disposed over the substrate on opposing sides of the image sensor.

8. The optical sensor of claim 1, wherein the encapsulant comprises an optically clear molding compound.

9. The optical sensor of claim 1, wherein the encapsulant and the light guide are integrally formed, wherein the encapsulant and the light guide comprise an optically clear molding compound.

10. The optical sensor of claim 1, further comprising:

an air gap disposed over the image sensor and disposed between the light guide and the image sensor.

11. The optical sensor of claim 1, further comprising:

a light filter disposed over the image sensor and disposed between the light guide and the image sensor.

12. The optical sensor of claim 11, further comprising:

an air gap disposed over the light filter and disposed between the light guide and the light filter.

13. The optical sensor of claim 11, wherein the light filter comprises a collimator filter.

14. The optical sensor of claim 1, further comprising:

a reflective layer disposed over the encapsulant.

15. The optical sensor of claim 14, wherein the reflective layer comprises a metallic coating over the surface positioned to reflect light, and wherein the metallic coating comprises a window in an area over the light guide and over an active area of the image sensor.

16. The optical sensor of claim 1, wherein the surface of the encapsulant is configured to reflect the light using Fresnel reflection.

17. The optical sensor of claim 1, wherein the surface of the encapsulant comprises a flat surface that is tilted relative to the light source.

18. The optical sensor of claim 1, wherein the surface of the encapsulant comprises a curved surface.

19. An optical fingerprint sensor package, comprising:

a package substrate;

an image sensor die disposed over the package substrate, wherein the image sensor die comprises a photodetector array and is electrically connected to the package substrate;

a light filter disposed over the image sensor die;

a light-emitting diode (LED) light source disposed over the package substrate;

a light guide disposed over the light filter;

an air gap disposed over the light filter between the light guide and the light filter; and

an optically clear molding compound disposed over the LED light source, wherein the optically clear molding compound is coupled to the light guide and comprises a surface positioned to reflect light emitted from the light source and direct the reflected light into the light guide.

20. The optical fingerprint sensor package of claim 19, wherein the light filter comprises a collimator filter, wherein the collimator filter is configured to transmit a set of incident light rays within an acceptance angle from a normal to the collimator filter, and wherein the collimator filter is configured to reject a set of incident light rays outside of an acceptance angle from the normal to the collimator filter.

21. An optical fingerprint sensor package, comprising:

a package substrate;

an image sensor die disposed over the package substrate, wherein the image sensor die comprises a photodetector array and is electrically connected to the package substrate;

a light-emitting diode (LED) light source disposed over the package substrate; and

an optically clear molding compound disposed over the LED light source, wherein the optically clear molding compound is coupled to the light guide and comprises a surface positioned to reflect light emitted from the light source and direct the reflected light to a sensing area above the image sensor die.

22. A method of forming an optical sensor package, the method comprising:

attaching an image sensor die to a substrate;

electrically connecting the image sensor die to the substrate;

mounting a light-emitting diode (LED) to the substrate; and

overmolding the LED with an optically clear molding compound, wherein a light guide is disposed over the image sensor die, and wherein the optically clear molding compound comprises a surface positioned to reflect light emitted from the LED and direct the reflected light into the light guide.

23. The method of claim 22, wherein the image sensor die is electrically connected to the substrate by wire bonding the image sensor die to the substrate.

24. The method of claim 22, wherein the image sensor die is attached to the substrate and electrically connected to the substrate by flip chip attaching the image sensor die to the substrate.