Method of uniform phosphor chip coating and LED package fabricated using method

• US 7,943,952 B2
• Filed: 07/27/2007
• Issued: 05/17/2011
• Est. Priority Date: 07/31/2006
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Laughner, Michael, Fu, Yankun, Letoquin, Ronan, Andrews, Peter, Medendorp, Nicholas W. Jr., Loh, Ban P.
• Primary Examiner(s): Mandala; Victor
• Assistant Examiner(s): STOWE, SCOTT C
• Application Number:
  US11/881,683
• Publication Number:
  US 20080079017A1
• Time in Patent Office: 1,390 Days
• Field of Search: 257/98, 257/99, 257/100, 257/E33.056, 257/E33.059, 257/E33.067, 257/E33.068, 257/E33.073, 257/79, 257/E33.061, 438/26, 438/29, 438/27, 313/512
• US Class Current: 257/100
• 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 2924/19107 off-chip wires
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 2933/005 relating to encapsulations
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/54 having a particular shape
• CPC Class Codes: H01L 33/58 Optical field-shaping elements

Abstract

Methods for fabricating LED packages comprising providing an LED chip and covering at least part of it with a liquid medium. An optical element is provided and placed on the liquid medium. The optical element is allowed to settle to a desired level and the liquid medium is cured. LED packages are also disclosed that are fabricated using the disclosed methods.

Claims

1. A method for fabricating an LED package, comprising:

selecting an amount of a liquid medium;

covering at least part of an LED chip with said liquid medium, said liquid medium directly contacting at least part of said LED chip;

placing an optical element on said liquid medium;

allowing said optical element to settle only on said liquid medium at a desired level; and

curing said liquid medium;

wherein said amount of said liquid medium relates to said desired level.

2. The method of claim 1, wherein said liquid medium comprises a material from the group thermoset plastics, silicones, and epoxies.

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

4. The method of claim 1, wherein said optical element is optically coupled to said liquid medium.

5. The method of claim 1, further comprising providing a substrate and mounting said LED chip to said substrate.

6. The method of claim 1, wherein said liquid medium further comprises phosphors or diffusants.

7. The method of claim 1, further comprising a meniscus holding feature around said LED chip to hold said liquid medium in a desired shape prior to curing.

8. The method of claim 1, wherein said optical element further comprises a layer of conversion material.

9. The method of claim 1, wherein said optical element further comprises an optical design.

23. The method of claim 1, wherein said curing is done prior to said optical element completely settling on said encapsulant.

24. The method of claim 1, wherein said curing is done after said optical element has completely settled on said encapsulant.

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

a substrate;

an LED chip mounted to said substrate;

cured medium over said LED chip and directly adjacent to said substrate; and

an optical element having a bottom surface optically coupled to and in direct contact only with said medium, said optical element held in place at a certain height above said LED chip by said medium, wherein said height relates only to the amount of said cured medium, and wherein said cured medium and said optical element have different coefficients of thermal expansion.

11. The LED package of claim 10, wherein said cured medium comprises a material from the group thermoset plastics, silicones, and epoxies.

12. The LED package of claim 10, wherein said optical element comprises a lens.

13. The LED package of claim 10, wherein said cured medium further comprises phosphors or diffusants.

14. The LED package of claim 10, further comprising a meniscus holding feature on said substrate and around said LED chip.

15. The LED package of claim 10, wherein said optical element further comprises a layer of conversion material.

16. The LED package of claim 10, wherein said optical element further comprises an optical design.

25. The LED package of claim 10, wherein said optical element is supported only by said medium.

26. The LED package of claim 10, wherein said optical element only contacts said medium.

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

a substrate;

an LED chip mounted to said substrate;

cured encapsulant over said LED chip and directly contacting said substrate; and

an optical element having a bottom surface optically coupled to and in direct contact only with said encapsulant, said optical element held in place at a certain height above said LED chip by said encapsulant, wherein said height is directly related to the amount of said encapsulant.

18. The LED package of claim 17, wherein said cured encapsulant comprises a material from the group thermoset plastics, silicones, and epoxies.

19. The LED package of claim 17, wherein said optical element comprises a lens.

20. The LED package of claim 17, wherein said cured encapsulant further comprises phosphors or diffusants.

21. The LED package of claim 17, further comprising a meniscus holding feature on said substrate and around said LED chip.

22. The LED package of claim 17, wherein said LED chip is in electrical contact with said substrate.

27. The LED package of claim 17, wherein said optical element is only supported by said encapsulant.

28. The LED package of claim 17, wherein said optical element only contacts said encapsulant.