Light emitting diode package with optical element

• US 20080023711A1
• 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: Ibbetson, James, Keller, Bernd, Becerra, Maryanne, Leung, Michael, Tarsa, Eric
• Granted Patent: US 8,735,920 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• 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 2933/005 relating to encapsulations
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H01L 33/58 Optical field-shaping elements

Abstract

A light emitting diode (LED) package comprising a substrate with an LED chip mounted to the substrate and in electrical contact with it. An inner material covers the LED chip, and a lens covers the inner material with the lens material being harder than the inner material. An adhesive is arranged between the substrate and the lens to hold the lens to the substrate and to compensate for different coefficients of thermal expansion (CTE) between the lens and the remainder of the package. A method for forming an LED package comprises providing a substrate with a first meniscus ring on a surface of the substrate. An LED chip is mounted to the substrate, within the meniscus ring. An inner material is deposited over the LED chip, and a lens material in liquid form is deposited over the inner material. The lens material held in a hemispheric shape by the first meniscus feature and the lens material is cured making it harder than the inner material.

Claims

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

a substrate;

an LED chip mounted to said substrate;

an inner material covering said LED chip;

a lens covering said inner material, said lens being harder than said inner material; and

an adhesive between said substrate and said lens, said adhesive holding said lens to said substrate and compensating for different coefficients of thermal expansion between said lens and the remainder of said package.

2. The LED package of claim 1, wherein said LED chip is in electrical contact with said substrate.

3. The LED package of claim 1, further comprising a first meniscus holding feature to hold said lens material in a desired shape prior to curing.

4. The LED package of claim 1, further comprising a second meniscus holding feature to hold said inner material in the desired shape prior to curing.

5. The LED package of claim 1, wherein said inner material comprises a silicone.

6. The LED package of claim 1, wherein said inner material has a lower Shore durameter reading than said lens.

7. The LED package of claim 1, wherein said lens comprises silicone.

8. The LED package of claim 1, wherein said inner material further comprises light conversion materials.

9. The LED package of claim 1, further comprising a wire bond to apply an electrical signal to said LED, at least part of said wire bond covered by said inner material.

10. The LED package of claim 1, wherein said inner material and said lens are hemispheric shaped.

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

a substrate;

an LED chip mounted to said substrate;

a first meniscus holding feature on said substrate around said LED chip;

an inner material covering said LED chip; and

a lens made of a material that is harder than said inner material, said lens having a substrate contacting surface and mounted on said substrate and over said inner material at said mounting surface, said meniscus holding feature defining the edge of said lens mounting surface.

12. The LED package of claim 11, further comprising adhesive between said substrate and said lens, said adhesive holding said lens to said substrate.

13. The LED package of claim 12, wherein said adhesive further compensates for different coefficients of thermal expansion between said lens and, the remainder of said package.

14. The LED package of claim 11, further comprising a second meniscus holding feature, said soft inner material having a substrate contacting surface, said second meniscus holding feature defining the edge of said inner material mounting surface.

15. The LED package of claim 11, wherein said soft inner material further comprises light conversion materials.

16. The LED package of claim 11, further comprising a wire bond to apply an electrical signal to said LED chip, at least part of said wire bond covered by said soft inner material.

17. The LED package of claim 11, wherein said inner material has a hardness measuring less than 50 on Shore durometer 00 Scale.

18. The LED package of claim 11, wherein said lens has a hardness measuring greater that 30 on Shore durometer A Scale.

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

a plurality of LEDs mounted on a substrate;

an inner material covering at least one of said LED chips;

a lens comprising a material harder than said inner material and covering each said inner material; and

an adhesive between said substrate and each said lens, said adhesive holding said lens to said substrate and compensating for different coefficients of thermal expansion between said lens and the remainder of said package.

20. The LED array of claim 19, wherein said substrate is arranged to apply an electrical signal to each of said LEDs.

21. A method for forming a light emitting diode (LED) package, comprising:

providing a substrate with a first meniscus ring on a surface of said substrate;

mounting an LED chip to said substrate, within said meniscus ring;

depositing an inner material over said LED chip;

depositing a lens material in liquid form over said inner material, said lens material held in a hemispheric shape by said first meniscus feature; and

curing said lens material making it harder than said inner material.

22. The method of claim 21, wherein said substrate is arranged such that an electrical signal applied to said substrate is conducted to said LED chip.

23. The method of claim 21, wherein said inner material is deposited in liquid form and then cured.

24. The method of claim 21, wherein said inner material is deposited over said LED chip in a hemispheric shape.

25. The method of claim 24, wherein said substrate further comprises a second meniscus ring, said inner material deposited over said LED chip in liquid form, said second meniscus ring holding said liquid soft inner material in a hemispheric shape.

26. The method of claim 25, further comprising curing said liquid inner material.

27. The method of claim 21, wherein said inner material has a cured hardness measuring less than 50 on Shore durometer 00 Scale.

28. The method of claim 21, wherein said lens has a cured hardness measuring greater that 30 on Shore durometer A Scale.

29. The method of claim 21, further comprising depositing an adhesive material between said substrate and said LED chip.

30. The method of claim 29, wherein said adhesive material holds said lens on said substrate and compensates for coefficient of thermal expansion (CTE) mismatches between said lens and remainder of said LED package.