Miniaturized optical proximity sensor

• US 8,350,216 B2
• Filed: 12/04/2009
• Issued: 01/08/2013
• Est. Priority Date: 09/10/2009
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Yao, Yufeng, Ong, Chi Boon, Tan, Wee Sin
• Primary Examiner(s): Porta, David
• Assistant Examiner(s): Maupin, Hugh H
• Application Number:
  US12/631,804
• Publication Number:
  US 20110057104A1
• Time in Patent Office: 1,131 Days
• Field of Search: 250/339.01
• US Class Current: 250/339.01
• CPC Class Codes: G01J 1/32 adapted for automatic variation of the measured or reference value regulation of light intensity G05D25/00
• CPC Class Codes: G01J 1/44 Electric circuits for command of an exposure part G03B7/02
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding
• CPC Class Codes: Y10T 29/49126 Assembling bases

Abstract

Various embodiments of a miniaturized optical proximity sensor are disclosed. In one embodiment, an ambient light sensor and a light detector are mounted on first and second spacers, which in turn are mounted to a top surface of an integrated circuit die-attached to a substrate. An optically-transmissive infrared pass compound is molded over the ambient light sensor, the light detector, the integrated circuit, a light emitter and peripheral portions of the substrate. Next, an optically non-transmissive infrared cut compound is molded over the optically-transmissive infrared pass compound to provide a miniaturized optical proximity sensor having no metal shield but exhibiting very low crosstalk characteristics.

Claims

1. An optical proximity sensor, comprising:

a substrate comprising a plurality of wire bond pads;

an infrared light emitter mounted atop the substrate and electrically connected to at least one of the wire bond pads;

a light detector mounted atop the substrate and electrically connected to at least one of the wire bond pads;

an integrated circuit mounted atop the substrate, the integrated circuit comprising light emitter driving and light detecting circuits operably connected to the light emitter and the light detector, respectively, the integrated circuit being operably connected to some of the plurality of wire bond pads;

at least one spacer comprising an electrically non-conductive dielectric material, the spacer being mounted to a top surface of the integrated circuit;

an ambient light sensor mounted to a top surface of the spacer, the ambient light sensor being electrically connected to at least one of the wire bond pads, wherein the light detector is mounted to the top surface of the spacer;

a first molded infrared light pass component disposed over and covering the light emitter;

a second molded infrared light pass component disposed over and covering the ambient light sensor and the light detector, and

a molded infrared light cut component disposed over and between the first and second molded infrared light pass components and over portions of the substrate, the molded infrared light cut component having first, second and third apertures disposed therethrough above the light emitter, the ambient light sensor, and the light detector, respectively.

2. The optical proximity sensor of claim 1, wherein at least a first portion of light emitted by the light emitter passes through the first component and the first aperture, and at least a second portion of the first portion of light reflected from an object of interest in proximity to the sensor passes through the third aperture and the second component for detection by the light detector, and the infrared light cut component substantially attenuates or blocks the transmission of undesired direct, scattered or reflected light between the light emitter and the light detector and thereby minimizes optical crosstalk and interference between the light emitter and the light detector.

3. The optical proximity sensor of claim 1, wherein at least one of the first and second infrared light pass components comprises an optically transmissive epoxy, polymer or plastic.

4. The optical proximity sensor of claim 1, wherein the infrared light cut component comprises a substantially optically non-transmissive moldable material, epoxy, polymer or plastic.

5. The optical proximity sensor of claim 1, wherein the infrared light cut component further comprises an infrared cut or blocking additive.

6. The optical proximity sensor of claim 1, wherein the substrate is a printed circuit board (“

PCB”

).

7. The optical proximity sensor of claim 1, wherein at least one of the light emitter, the ambient light sensor and the light detector is a semiconductor die.

8. The optical proximity sensor of claim 1, wherein the integrated circuit is an application specific integrated circuit (“

ASIC”

).

9. The optical proximity sensor of claim 1, wherein the at least one spacer comprises first and second spacers separated from one another atop the integrated circuit, the ambient light sensor being mounted atop the first spacer and the light detector being mounted atop the second spacer.

10. The optical proximity sensor of claim 9, wherein at least portions of the second spacer are coated with an electrically conductive metal.

11. The optical proximity sensor of claim 1, wherein the at least one spacer comprises silicon or a semiconductor material.

12. The optical proximity sensor of claim 11, wherein the portable electronic device is a smart phone, a mobile telephone, a personal data assistant (PDA), a laptop computer, a notebook computer, or a computer.

13. The optical proximity sensor of claim 1, wherein the optical proximity sensor is incorporated into a portable electronic device.

14. The optical proximity sensor of claim 1, wherein the light emitter is an LED.

15. The optical proximity sensor of claim 1, wherein the light detector is a positive-intrinsic-negative (“

PIN”

) diode.

16. The optical proximity sensor of claim 1, wherein a molded optically transmissive lens is formed over at least one of the light emitter, the ambient light sensor and the light detector.

17. A method of making an optical proximity sensor, comprising:

mounting an infrared light emitter atop a substrate comprising a plurality of wire bond pads and electrically connecting the light emitter to at least one of the wire bond pads;

mounting a light detector atop the substrate and electrically connecting the light detector to at least one of the wire bond pads;

mounting an integrated circuit atop the substrate, the integrated circuit comprising light emitter driving and light detecting circuits operably connected to the light emitter and the light detector, respectively, and electrically connecting the integrated circuit to some of the plurality of wire bond pads;

mounting at least one spacer comprising an electrically non-conductive dielectric material to a top surface of the integrated circuit;

mounting an ambient light sensor to a top surface of the spacer, and electrically connecting the ambient light sensor to at least one of the wire bond pads, wherein the mounting of the light detector includes mounting the light detector to the top surface of the spacer;

molding or casting a first infrared light pass component over the light emitter;

molding or casting a second infrared light pass component over the ambient light sensor and the light detector, and

molding or casting an infrared light cut component over and between the first and second infrared light pass components and over portions of the substrate, the molded infrared light cut component having first, second and third apertures disposed therethrough above the light emitter, the ambient light sensor, and the light detector, respectively.

18. The method of claim 17, further comprising configuring the light detector and the light emitter with respect to one another such that at least a first portion of light emitted by the light emitter passes through the first component and the first aperture and at least a second portion of the first portion of light reflected from an object of interest in proximity to the sensor passes through the third aperture for detection by the light detector.

19. The method of claim 17, further comprising configuring the infrared light cut component to substantially attenuate or block the transmission of undesired direct, scattered or reflected light between the light emitter and the light detector thereby to minimize optical crosstalk and interference between the light emitter and the light detector.

20. The method of claim 17, further comprising forming optically transmissive lenses over the light emitter, the ambient light sensor and the light detector when the first and second optically transmissive infrared light pass components are molded or casted.

21. The method of claim 17, wherein the light emitter or the light detector is die-attached to the substrate.

22. The method of claim 17, wherein the first and second optically transmissive infrared light pass components are casted or transfer-molded.

23. The method of claim 17, wherein the first and second optically transmissive infrared light pass components are casted or transfer-molded at the same time and later separated by a channel sawn or cut therebetween.

24. The method of claim 17, wherein the at least one spacer further comprises first and second spacers separated from one another atop the integrated circuit, the ambient light sensor being mounted atop the first spacer and the light detector being mounted atop the second spacer.

25. The method of claim 24, wherein at least portions of the second spacer are coated with an electrically conductive metal.

26. The method of claim 17, wherein the at least one spacer comprises silicon or a semiconductor material.

27. The method of claim 17, further comprising incorporating the optical proximity sensor into a portable electronic device.

28. The method of claim 27, wherein the portable electronic device is a smart phone, a mobile telephone, a personal data assistant (PDA), a laptop computer, a notebook computer, or a computer.