Encapsulant profile for light emitting diodes

• US 7,910,938 B2
• Filed: 08/16/2007
• Issued: 03/22/2011
• Est. Priority Date: 09/01/2006
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Bergmann, Michael J., Collins, Brian T., Emerson, David T., Hussell, Christopher P.
• Primary Examiner(s): Mandala; Victor
• Assistant Examiner(s): STOWE, SCOTT C
• Application Number:
  US11/839,603
• Publication Number:
  US 20080054284A1
• Time in Patent Office: 1,314 Days
• Field of Search: 257/79, 257/94, 257/98, 257/100, 257/95, 257/E33.067, 257/E33.068, 257/E33.071, 257/E33.055, 257/E33.059, 257/E33.057
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/48091 Arched
• 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 2924/00014 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 2924/3011 Impedance
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/54 having a particular shape
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

A light emitting packaged diode ids disclosed that includes a light emitting diode mounted in a reflective package in which the surfaces adjacent the diode are near-Lambertian reflectors. An encapsulant in the package is bordered by the Lambertian reflectors and a phosphor in the encapsulant converts frequencies emitted by the LED chip and, together with the frequencies emitted by the LED chip, produces white light. A substantially flat meniscus formed by the encapsulant defines the emitting surface of the packaged diode.

Claims

1. A light emitting packaged diode comprising:

a light emitting diode chip mounted in a reflective package in which the surfaces of the reflective package adjacent said diode are near-Lambertian reflectors;

an encapsulant in said package and bordered by said near-Lambertian reflectors;

a phosphor in said encapsulant that converts frequencies emitted by said chip and that together with the frequencies emitted by said chip produces white light; and

a domed meniscus that does not exceed 50 microns from said reflective package, said meniscus formed by said encapsulant and said package, said meniscus defining the emitting surface of said packaged diode.

2. A packaged diode according to claim 1 comprising a light emitting diode chip with a near-Lambertian far field pattern.

3. A packaged diode according to claim 1 wherein said encapsulant comprises a plurality of layers of said encapsulant.

4. A light emitting packaged diode according to claim 1 wherein said light emitting diode is formed from the Group III nitride material system.

5. A light emitting packaged diode according to claim 1 wherein said phosphor comprises cerium doped yttrium aluminum garnet.

6. A light emitting packaged diode according to claim 1 wherein said reflective package comprises a white resin.

7. A light emitting packaged diode according to claim 1 wherein said encapsulant includes a diffuser.

8. A light emitting packaged diode according to claim 1 wherein said encapsulant comprises a polysiloxane resin.

9. A display that incorporates the packaged diode of claim 1 in a side view surface mount orientation in combination with a light guide.

27. A light emitting packaged diode according to claim 1, wherein:

said package defines a top surface; and

said meniscus is maintained within 50 microns of a plane defined by the top surface of said package.

30. A packaged diode according to claim 1 wherein said domed meniscus does not exceed 50 microns from a top surface of said reflective package.

10. A light emitting packaged diode comprising:

a light emitting diode chip mounted in a side view surface mount reflective package in which the surfaces of the reflective package adjacent said diode are near-Lambertian reflectors;

an encapsulant in said package and bordered by said near-Lambertian reflectors;

a phosphor in said encapsulant that converts frequencies emitted by said chip and that together with the frequencies emitted by said chip produces white light; and

a domed meniscus that does not exceed 50 microns from said reflective package, said meniscus formed by said encapsulant and said package, said meniscus defining the emitting surface of said packaged diode.

11. A packaged diode according to claim 10 comprising a light emitting diode with a near-Lambertian far field pattern.

12. A packaged diode according to claim 10 wherein said encapsulant comprises a plurality of layers of said encapsulant.

13. A light emitting packaged diode according to claim 10 wherein said light emitting diode is formed from the Group III nitride material system.

14. A light emitting packaged diode according to claim 10 wherein said phosphor comprises cerium doped yttrium aluminum garnet.

15. A light emitting packaged diode according to claim 10 wherein said reflective package comprises a white resin.

16. A light emitting packaged diode according to claim 10 wherein said encapsulant includes a diffuser.

17. A light emitting packaged diode according to claim 10 wherein said encapsulant comprises a polysiloxane resin.

18. A light emitting packaged diode according to claim 10 wherein said phosphor is positioned to cover only the emissive area of said chip.

28. A light emitting packaged diode according to claim 10, wherein:

said package defines a top surface; and

said meniscus is maintained within 50 microns of a plane defined by the top surface of said package.

31. A packaged diode according to claim 10 wherein said domed meniscus does not exceed 50 microns from a top surface of said reflective package.

19. A lighted display comprising:

a light guide;

at least one packaged light emitting diode along one edge of said light guide;

said packaged diode including,

a reflective package with near-Lambertian reflectors,

a light emitting diode chip in said reflective package,

an encapsulant in said package and covering said chip,

a phosphor in said encapsulant that converts frequencies emitted by said chip and that together with the frequencies emitted by said chip produce white light, and

a domed meniscus that does not exceed 50 microns from said reflective package, said meniscus formed by said encapsulant and said package, said meniscus defining the emitting surface of said packaged diode against the edge of said light guide.

20. A lighted display according to claim 19 wherein said packaged diode is a side view surface mount package with a rectangular profile with the light emitting surface of said domed encapsulant forming an arc-shaped profile that extends in the direction of primary emission of said chip and toward said edge of said light guide.

21. A lighted display according to claim 19 wherein said diode chip is formed from the Group III nitride material system.

22. A lighted display according to claim 19 wherein said reflective package is a white polymer resin.

23. A lighted display according to claim 19 including at least two packaged light emitting diodes along at least one edge of said light guide.

24. A lighted display according to claim 23 wherein said light guide is rectangular and has substantially planar dimensions.

25. A lighted display according to claim 19 wherein said encapsulant is a polysiloxane resin.

26. A lighted display according to claim 19 wherein said phosphor comprises cerium-doped yttrium aluminum garnet.

29. A lighted display according to claim 19, wherein:

said package defines a top surface; and

said meniscus is maintained within 50 microns of a plane defined by the top surface of said package.

32. A lighted display according to claim 19 wherein said domed meniscus does not exceed 50 microns from top surface of said reflective package.