Light-emitting diode (LED) package and packaging method for shaping the external light intensity distribution

• US 20020185651A1
• Filed: 06/08/2001
• Published: 12/12/2002
• Est. Priority Date: 06/08/2001
• Status: Active Grant

• Current Assignee: Current Lighting Solutions, LLC (f/k/a GE Lighting Solutions, LLC) (American Industrial Partners)
• Original Assignee: Gelcore (General Electric Company)
• Inventors: Sommers, Mathew L.
• Granted Patent: US 6,674,096 B2
• Time in Patent Office: Days
• US Class Current: 257/94
• CPC Class Codes: H01L 2924/1815 Shape
• CPC Class Codes: H01L 33/54 having a particular shape

Abstract

An LED package (10) includes LED die (12) mounted onto lead frame (14) and electrically connected thereto whereby LED die (12) is electrically energized through leads (16, 18). An encapsulant (20), preferably an epoxy resin, encapsulates and preferably hermetically seals LED die (12). Encapsulant (20) includes depression (24) defined by preselected curved surfaces (28), at least a portion of which are coated by reflective coating (26). Encapsulant (20) preferably also includes sides (22) with preselected curvature. In operation, LED die (12) emits light (32) directed approximately along LED die surface normal (36). Light rays (32) reflect from reflective surface (26) and reflected rays (38) are subsequently refracted by refracting surface (22) so that refracted rays (40) exit the capsule. The reflecting surface (26) and refracting surface (22) cooperate to convert LED die light distribution (32) into light distribution (40) which appears to emanate from an approximate point source (42).

Claims

1. A light emitting diode (LED) package, comprising:

a transparent encapsulant surrounding the LED die; and

a reflective surface disposed on the encapsulant surface essentially opposite the LED die surface.

2. The LED package of claim 1, wherein:

the encapsulant surrounding the LED is essentially hemispherical in shape; and

the encapsulant surface near the reflective surface is spatially depressed with respect to the essentially hemispherical shape such that LED radiation incident upon the reflective surface is reflected essentially toward a side of the package.

3. The LED package of claim 2, wherein the reflective surface and the curvature of the encapsulant surface are arranged so that LED radiation reflected from the reflective surface and subsequently exiting the encapsulant appears to an associated viewer as emanating from an approximate point light source.

4. The LED package of claim 2, wherein the reflective surface and the curvature of the encapsulant surface are arranged so that LED radiation reflected from the reflective surface and subsequently exiting the encapsulant appears to an associated viewer as emanating from an approximate line light source.

5. The LED package of claim 1, wherein the encapsulant has essentially straight sides;

and the encapsulant has a top which includes a depression in the vicinity of the reflective surface such that LED radiation incident upon the reflective surface is reflected essentially toward a side of the package.

6. The LED package of claim 1, wherein the reflective surface is a reflective coating applied to the encapsulant.

7. The LED package of claim 1, wherein the encapsulant is an epoxy resin.

8. The LED package of claim 1, wherein the encapsulant is essentially radially symmetric about an LED surface normal.

9. The LED package of claim 1, wherein:

the encapsulant exhibits reflection symmetry about a plane containing an LED die surface normal and has a curved surface defining an essentially linear depression; and

the reflective coating is disposed upon at least a portion of the curved surface defining the linear depression.

10. The LED package of claim 1, wherein the encapsulant hermetically seals the LED die.

11. A method for manufacturing a light-emitting diode (LED) package which emits light in an essentially non-directional manner over at least a predetermined solid angle, the method comprising:

mounting an LED die to a lead frame;

electrically connecting the LED die to the leads of the lead frame; and

encapsulating at least the LED die in a transparent encapsulant; and

applying a reflective coating to a portion of the encapsulant essentially opposite the LED die.

12. The method of claim 11, wherein the encapsulating also hermetically seals at least the LED die.

14. The LED capsule of claim 13 wherein the reflective surface is disposed essentially opposite to the light-emitting surface of the LED die.

15. The LED capsule of claim 14, further comprising:

a refracting surface which cooperates with the reflective surface to convert the distribution of the LED die light emission intensity into a preselected external light emission intensity distribution.

16. The LED capsule of claim 15, wherein reflective portions of the lead frame surface cooperate with the reflective and refracting surfaces to convert the distribution of the LED die light emission intensity into a preselected external light emission intensity distribution.

17. The LED capsule of claim 15, wherein the refracting surface is a portion of the encapsulant outer surface which has a preselected curvature.

18. The LED capsule of claim 15, wherein the preselected external light emission intensity distribution is an apparent approximate point source light emission intensity distribution.

19. The LED capsule of claim 15, wherein the preselected external light emission intensity distribution is an apparent approximate line source light emission intensity distribution.

20. The LED capsule of claim 15, wherein the transparent encapsulant hermetically seals the LED die.

13. A light emitting diode (LED) capsule, comprising:

a lead frame;

an LED die mounted onto the lead frame and electrically connected thereto;

a transparent encapsulant which encapsulates the LED die and at least a portion of the lead frame; and

a reflective surface disposed on a portion of the encapsulant outer surface.

21. A light emitting diode (LED) capsule for producing an approximate extended light source with essentially uniform intensity distribution over an extended solid viewing angle, the LED capsule comprising:

a lead frame;

an LED die mounted onto the lead frame and electrically connected thereto;

a transparent encapsulant which encapsulates the LED die and at least a portion of the lead frame; and

a roughened surface disposed on at least a portion of the encapsulant outer surface.

22. The LED capsule of claim 21, wherein the roughened surface is a roughened depression in the encapsulant positioned essentially opposite the LED die.

23. The LED capsule of claim 22, wherein the depression is conically shaped.

24. The LED capsule of claim 22, further comprising:

a reflective filling disposed within the depression and essentially conforming with the roughness of the roughened surface.

25. The LED capsule of claim 21 further comprising:

a coating of reflective material disposed upon at least a portion of the roughened surface.

26. The method of claim 21, wherein the encapsulant hermetically seals at least the LED die.