Compact optical proximity sensor with ball grid array and windowed substrate

• US 8,716,665 B2
• Filed: 09/10/2009
• Issued: 05/06/2014
• Est. Priority Date: 09/10/2009
• Status: Expired due to Fees

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Yao, Yufeng, Ong, Chi Boon, Tan, Wee Sin
• Primary Examiner(s): Porta, David
• Assistant Examiner(s): GREEN, YARA B
• Application Number:
  US12/557,438
• Publication Number:
  US 20110057108A1
• Time in Patent Office: 1,699 Days
• Field of Search: 250/336.1, 250/338.1, 250/339.01, 250/339.02, 250/339.06, 250/339.11, 250/338.4, 250/340, 250/341.1, 250/342, 250/201.1, 250/341.8, 340/600, 438/55, 438/57, 438/64, 438/65, 438/66, 438/70, 438/98, 438/26, 438/25, 257/100, 257/433, 257/435, 257/436, 396/439
• US Class Current: 250/338.1
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 17/48 Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• 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 2924/00014 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 2924/3025 Electromagnetic shielding
• CPC Class Codes: H01L 31/0203 Containers; Encapsulations , e.g. encapsulation of photodiodesfor photovoltaic devices H01L31/048; for organic photosensitive devices H10K30/80
• CPC Class Codes: H01L 31/173 formed in, or on, a common substrate
• CPC Class Codes: H03K 17/941 using an optical detector H03K17/968 takes precedence
• CPC Class Codes: H03K 2017/9455 constructional details of proximity switches using a magnetic detector H03K17/9505

Abstract

Various embodiments of a compact optical proximity sensor with a ball grid array and windowed or apertured substrate are disclosed. In one embodiment, the optical proximity sensor comprises a printed circuit board (“PCB”) substrate comprising an aperture and a lower surface having electrical contacts disposed thereon, an infrared light emitter and an infrared light detector mounted on an upper surface of the substrate, an integrated circuit located at least partially within the aperture, a molding compound being disposed between portions of the integrated circuit and substrate, an ambient light detector mounted on an upper surface of the integrated circuit, first and second molded infrared light pass components disposed over and covering the infrared light emitter and the infrared light detector, respectively, and a molded infrared light cut component disposed between and over portions of the first and second infrared light pass components.

Claims

1. An optical proximity sensor, comprising:

a printed circuit board (“

PCB”

) substrate comprising an upper surface, a lower surface having electrical contacts disposed thereon, and an aperture extending through the substrate from the upper surface to the lower surface;

a light emitter and a light detector mounted on the upper surface of the substrate;

an integrated circuit located at least partially within the aperture, a molding compound being disposed between portions of the integrated circuit and substrate, the integrated circuit having an upper surface and a lower surface, the upper surface of the integrated circuit being substantially flush with the upper surface of the substrate such that the upper surface of the integrated circuit is substantially flush with a bonding region configured to have a lower surface of the light emitter mounted thereto and a bonding region configured to have a lower surface of the light detector mounted thereto, the lower surface of the integrated circuit being configured to be wire bonded to the electrical contacts on the lower surface of the substrate, the molding compound being further configured to protect wire bonds between the lower surface of the integrated circuit and the electrical contacts on the lower surface of the substrate;

an ambient light detector mounted on the upper surface of the integrated circuit;

first and second molded light pass components disposed over and covering the light emitter and the light detector, respectively; and

a molded light cut component disposed between and over portions of the first and second light pass components.

2. The optical proximity sensor of claim 1, wherein the light emitter and the light detector are mounted on the upper surface of the substrate on opposing sides of the aperture and wherein the molded light cut component at least partially contacts the upper surface of the integrated circuit.

3. The optical proximity sensor of claim 1, wherein the lower surface of the integrated circuit is overmolded with the molding compound.

4. The optical proximity sensor of claim 1, wherein the molding compound comprises an epoxy, plastic, a thermosetting plastic, a polymer or polyimide.

5. The optical proximity sensor of claim 1, wherein the substrate comprises fiberglass, glass, ceramic, polyimide, polyimide film, a polymer, an organic material, a flex circuit material, epoxy, epoxy resin, a printed circuit board material, PTFE and glass, PTFE and ceramic, glass and ceramic, thermoset plastic, or plastic.

6. The optical proximity sensor of claim 1, wherein a ball grid array is mounted on the electrical contacts on the lower surface of the substrate.

7. The optical proximity sensor of claim 1, wherein the ambient light detector is electrically connected to the substrate by wires and wire bond pads.

8. 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 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 second component for detection by the light detector.

9. The optical proximity sensor of claim 1, wherein the light cut component substantially attenuates or blocks 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.

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

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

12. The optical proximity sensor of claim 1, wherein the light cut component further comprises a cut or blocking additive.

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

14. The optical proximity sensor of claim 1, wherein the substrate comprises at least one conductive via that electrically connects the lower surface of the integrated circuit to at least one of the light emitter and light detector.

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

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

PIN”

) diode.

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

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

19. The optical proximity sensor of claim 18, wherein the portable electronic device is a mobile telephone, a personal data assistant (PDA), a laptop computer, a notebook computer, or a computer.

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

providing a printed circuit board (“

PCB”

) substrate comprising an upper surface, a lower surface having electrical contacts disposed thereon, and an aperture extending through the substrate from the upper surface to the lower surface;

mounting a light emitter and a light detector on the upper surface of the substrate;

positioning an integrated circuit at least partially within the aperture such that an upper surface of the integrated circuit is substantially flush with the upper surface of the substrate as well as a lower surface of the light emitter and a lower surface of the light detector;

bonding one or more wires between a lower surface of the integrated circuit and the electrical contacts on the lower surface of the substrate;

placing a molding compound between portions of the integrated circuit and substrate, the molding compound also physically protecting the one or more wires that have been bonded between the lower surface of the integrated circuit and the electrical contacts on the lower surface of the substrate;

mounting an ambient light detector on the upper surface of the integrated circuit;

molding first and second light pass components over and covering the light emitter and the light detector, respectively; and

molding a light cut component between and over portions of the first and second light pass components.

21. The method of claim 20, wherein the light emitter and the light detector are mounted on the upper surface of the substrate on opposing sides of the aperture and wherein one or more electrically-conductive vias in the substrate provide an electrical connection between the integrated circuit and at least one of the light emitter and the light detector.

22. The method of claim 20, wherein the lower surface of the integrated circuit is overmolded with the molding compound.

23. The method of claim 20, further comprising mounting a ball grid array on the electrical contacts on the lower surface of the substrate.

24. The method of claim 20, further comprising electrically connecting the ambient light detector to the upper surface of the substrate by wires and wire bond pads.

25. The method of claim 20, further comprising molding an optically transmissive lens over at least one of the light emitter and the light detector.

26. The method of claim 20, further comprising incorporating the optical proximity sensor into a portable electronic device.