Light emitting diode package element with internal meniscus for bubble free lens placement

• US 20080026498A1
• Filed: 07/31/2006
• Published: 01/31/2008
• Est. Priority Date: 07/31/2006
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Becerra, Maryanne, Tarsa, Eric, Yadev, Praveen, Yuan, Thomas C.
• Granted Patent: US 7,804,147 B2
• Time in Patent Office: Days
• US Class Current: 438/26
• CPC Class Codes: H01L 2224/48091 Arched
• 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 33/52 Encapsulations
• CPC Class Codes: H01L 33/58 Optical field-shaping elements

Abstract

A method for fabricating a light emitting diode (LED) package comprising providing an LED chip and covering at least part of the LED chip with a liquid encapsulant having a radius of curvature. An optical element is provided having a bottom surface with at least a portion having a radius of curvature larger than the liquid encapsulant. The larger radius of curvature portion of the optical element is brought into contact with the liquid encapsulant. The optical element is then moved closer to the LED chip, growing the contact area between said optical element and said liquid encapsulant. The liquid encapsulant is then cured. A light emitting diode comprising a substrate with an LED chip mounted to it. A meniscus ring is on the substrate around the LED chip with the meniscus ring having a meniscus holding feature. An inner encapsulant is provided over the LED chip with the inner encapsulant having a contacting surface on the substrate, with the meniscus holding feature which defines the edge of the contacting surface. An optical element is included having a bottom surface with at least a portion that is concave. The optical element is arranged on the substrate with the concave portion over the LED chip. A contacting encapsulant is included between the inner encapsulant and optical element.

Claims

1. A method for fabricating a light emitting diode (LED) package, comprising:

providing an LED chip;

covering at least part of said LED chip with a contacting liquid encapsulant having a radius of curvature;

providing an optical element having a bottom surface with at least a portion having a radius of curvature larger than said liquid encapsulant;

contacting said larger radius of curvature portion of said optical element with said liquid encapsulant;

moving said optical element closer to said LED chip growing the contact area between said optical element and said liquid encapsulant; and

curing said liquid encapsulant.

2. The method of claim 1, wherein said contact area grows out as said optical element moves closer to said LED chip, reducing air entrapment between said liquid encapsulant and said optical element.

3. The method of claim 1, wherein said optical element comprises a substantially hemispheric lens.

4. The method of claim 3, wherein said hemispheric lens has a bottom surface with a concave portion having a larger radius of curvature than said contacting liquid encapsulant.

5. The method of claim 1, wherein said larger radius of curvature portion of said optical element contacts said liquid encapsulant at the highest point of said encapsulant.

6. The method of claim 1, further comprising an inner encapsulant directly covering said LED chip, said liquid encapsulant provided on said inner encapsulant.

7. The method of claim 1, further comprising providing a substrate, said LED mounted to said substrate.

8. The method of claim 7, wherein said substrate further comprises a meniscus ring around said LED chip.

9. The method of claim 8, further comprising depositing a liquid inner encapsulant directly over said LED chip and curing said inner encapsulant, said meniscus ring holding said liquid inner encapsulant in a substantially hemispheric shape until cured, said contacting liquid encapsulant provided on said cured inner encapsulant.

10. The method of claim 8, wherein said meniscus ring comprises a lens retention feature, to retain said optical element in said package against lateral forces.

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

a substrate with an LED chip mounted to it;

a meniscus ring on said substrate around said LED chip, said meniscus ring having a meniscus holding feature;

an inner encapsulant over said LED chip and having a contacting surface on said substrate, said meniscus holding feature defining the edge of said contacting surface;

an optical element having a bottom surface with at least a portion that is concave, said optical element on said substrate with said concave portion over said LED chip; and

a contacting encapsulant between said inner encapsulant and said optical element.

12. The LED package of claim 11, wherein said optical element comprises a substantially hemispheric lens.

13. The LED package of claim 11, wherein said LED chip is at least partially within said concave portion of said optical element.

14. The LED package of claim 11, wherein the inner encapsulant has a radius of curvature and said optical element concave portion has a radius of curvature, said concave portion having a larger radius of curvature than said inner encapsulant.

15. The LED package of claim 11, wherein there is substantially no air trapped between said optical element and said contacting encapsulant.

16. The LED package of claim 11, wherein said meniscus forming feature further comprises an optical element retention feature.

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

an LED chip;

a cured encapsulant over said LED chip;

an optical element with a bottom surface, said bottom surface on said cured encapsulant with substantially no air trapped between the two by placing said optical element on said encapsulant prior to curing, said encapsulant prior to curing having a radius of curvature and said bottom surface having at least a portion with a radius of curvature larger than said encapsulant'"'"'s radius of curvature, said bottom surface brought into contact with said encapsulant and moved toward said LED chip pushing out air as the contact area between the two grows.

18. The LED package of claim 17, wherein said optical element comprises wherein said bottom surface of said optical element comprises a concave portion, said LED chip at least partially within said concave portion.

19. The LED package of claim 17, wherein said optical element is a substantially hemispheric lens.

20. The LED package of claim 17, further comprising a substrate, said LED chip mounted to said substrate.

21. The LED package of claim 20, further comprising a meniscus ring around said LED chip.

22. The LED package of claim 21, wherein said pre-cured encapsulant is held in a substantially hemispheric shape by said meniscus ring.

23. The LED package of claim 21, wherein said encapsulant comprises an inner encapsulant and a contacting encapsulant, said inner encapsulant held in a substantially hemispheric shape by said meniscus ring prior to curing and said contacting encapsulant being on said inner encapsulant.

24. The LED package of claim 21, wherein said meniscus ring further comprises an optical element retention feature.

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

a substrate with a plurality of LED chips;

an inner encapsulant over each of said LED chips, said inner encapsulant having a contacting surface on said substrate;

an optical element over each of said LED chips, each optical element having a bottom surface with at least a portion that is concave, with said concave portion over said LED chip; and

a contacting encapsulant between said each said inner encapsulant and its said optical element.

26. The LED array package of claim 25, wherein said LEED chips are mounted to said substrate so that electrical signals applied to said substrate are conducted from said substrate to said LED chips

27. The LED array package of claim 25, further comprising a meniscus ring on said substrate around each of said LED chips, each said meniscus ring having a meniscus holding feature defining the edge of each said inner encapsulant contacting surface.

28. The LED array package of claim 25, wherein each of said LED chips is at least partially within said concave portion of its said optical element.

29. The LED array package of claim 25, wherein the inner encapsulant has a radius of curvature and said optical element concave portion has a radius of curvature, said concave portion having a larger radius of curvature than said inner encapsulant.

30. The LED array package of claim 25, wherein substantially no air is trapped between each said optical element and its said contacting encapsulant.

31. The LED array package of claim 25, wherein said meniscus forming feature further comprises an optical element retention feature.