Top-surface-mount power light emitter with integral heat sink

• US 20060292747A1
• Filed: 06/27/2005
• Published: 12/28/2006
• Est. Priority Date: 06/27/2005
• Status: Abandoned Application

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Loh, Ban P.
• Application Number:
  US11/168,018
• Publication Number:
  US 20060292747A1
• Time in Patent Office: Days
• US Class Current: 438/116
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 33/60 Reflective elements
• CPC Class Codes: H01L 33/64 Heat extraction or cooling elements
• CPC Class Codes: H01S 5/02212 Can-type, e.g. TO-CAN housings with emission along or parallel to symmetry axis

Abstract

A light emitting apparatus is disclosed. The light emitting apparatus includes a substrate, a heat sink, a dielectric layer, conductive traces, a reflector, and at least one photonic device. The substrate has a top surface and a bottom surface, a portion of the top surface defining a mounting pad. The heat sink is equipped with cooling fins to cool the substrate. The conductive traces are on the top surface of the substrate and extend from the mounting pad to a side edge of the substrate. The reflector is attached to the top surface of the substrate. The reflector surrounds the mounting pad partially covering the top surface of the substrate. The photonic device is attached to the substrate at the mounting pad, the photonic device connected to at least one conductive trace. The light emitting apparatus can be mounted on a board having connection traces. The connection traces of the board are aligned with the conductive trace of the light emitting apparatus to effect electrical connection.

Claims

1. An apparatus comprising:

a substrate having a top surface and a bottom surface, a portion of the top surface defining a mounting pad;

a plurality of conductive traces on the top surface of said substrate, said conductive traces extending from the mounting pad to a side edge of said substrate and said conductive traces comprising electrically conductive material;

a reflector attached to the top surface of said substrate, said reflector surrounding the mounting pad while leaving other portions of the top surface of said substrate and potions of the conductive traces exposed, said reflector partially defining an optical cavity;

at least one photonic device attached to at least one conductive trace at the mounting pad; and

a heat sink attached to the bottom surface of said substrate.

2. The apparatus recited in claim 1 wherein the photonic device is at least one of light emitting diode (LED) and laser.

3. The apparatus recited in claim 1 wherein the substrate comprises thermally conductive material.

4. The apparatus recited in claim 1 wherein the substrate comprises material selected from a group consisting of Aluminum (Al) and Copper (Cu) and further comprising a dielectric layer between said substrate and said conductive traces.

6. The apparatus recited in claim 1 wherein said photonic device is wire bonded to at least one conductive trace.

7. The apparatus recited in claim 1 further comprising encapsulant filling the optical cavity.

8. The apparatus recited in claim 7 further comprising a lens in contact with said encapsulant thereby optically coupled to the photonic device.

9. The apparatus recited in claim 7 further wherein said encapsulant comprises at least one of diffusants and phosphors.

10. The apparatus recited in claim 7 further wherein said encapsulant comprises material selected from a group consisting of Titanium dioxide, Barium Sulfate.

11. The apparatus recited in claim 7 further wherein said encapsulant comprises phosphor material that absorbs light having a first wavelength and emit light having a second wavelength.

12. The apparatus recited in claim 1 wherein the top surface is optically reflective.

13. The apparatus recited in claim 1 wherein said reflector includes an optically reflective surface surrounding the optical cavity.

14. The apparatus recited in claim 13 wherein the optically reflective surface has diffusion grating.

15. The apparatus recited in claim 1 wherein the top surface comprises aluminum oxide.

16. The apparatus recited in claim 1 wherein said conductive traces comprise silver.

17. The apparatus recited in claim 1 wherein the substrate comprises plastic.

18. The apparatus recited in claim 17 wherein the substrate comprises material selected from a group consisting of Polyphthalamide Polyimide, and Liquid Crystal Polymer filled with thermal conductive material such as graphite or ceramics or optical reflective material such as Titanium Dioxide.

5. The apparatus recited in claim 5 wherein the dielectric layer comprises material selected from a group consisting of glass coating, polymer, and anodized substrate material.

19. A method of fabricating an apparatus, the method comprising:

providing a substrate having a top surface and a bottom surface, a portion of the top surface defining a mounting pad, the substrate having conductive traces on the top surface;

attaching at least one photonic device on the mounting pad, the photonic device in contact with at least one conductive trace; and

attaching a reflector on the top surface of the substrate, the reflector surrounding the mounting pad and partially defining an optical cavity.

20. The method recited in claim 19 further comprising:

forming a heat sink to the bottom surface of the substrate; and

filling the optical cavity with encapsulant.

21. The method recited in claim 20 further comprising attaching a lens on the reflector.

22. The method recited in claim 19 wherein the step of providing the substrate comprises manufacturing the substrate using coining or impact extrusion technique.

23. The method recited in claim 19 wherein a heat sink is integrally manufactured as part of the substrate during the coining or impact extrusion process.

24. The method recited in claim 23 wherein the heat sink comprises cooling fins.

25. The method recited in claim 19 wherein the step of attaching the reflector includes heat-staking the reflector to said substrate.

26. The method recited in claim 19 wherein the substrate is anodized to produce aluminum oxide layer surface.

27. The method recited in claim 19 wherein the substrate is insert-molded lead-frame with thermally conductive plastic.

28. An apparatus comprising:

a board having a front surface and a back surface, said board defining an opening, and said board having electrically conductive connection traces on its back surface;

a light emitting apparatus mounted within the opening of said board wherein the light emitting apparatus comprises;

a substrate having a top surface and a bottom surface, a portion of the top surface defining a mounting pad;

a plurality of conductive traces on the top surface of said substrate, said conductive traces extending from the mounting pad to a side edge of said substrate and said conductive traces comprising electrically conductive material;

a reflector attached to the top surface of said substrate, said reflector surrounding the mounting pad while leaving other portions of the top surface of said substrate and potions of the conductive traces exposed, said reflector defining an optical cavity;

at least one photonic device attached to the substrate at the mounting pad, the photonic device connected to at least one conductive trace; and

wherein at least one conductive trace of at least one light emitting apparatus is aligned with at least one connection trace of said board.

29. The apparatus recited in claim 28 wherein the light emitting apparatus is mounted on said board using surface mount technology.

30. The apparatus recited in claim 28 wherein the light emitting apparatus is mounted on said board with a mounting medium.

31. The apparatus recited in claim 30 wherein the mounting medium is selected from a group consisting of solder, epoxy, and connector.