Layered phosphor coatings for led devices

• US 20040124429A1
• Filed: 12/31/2002
• Published: 07/01/2004
• Est. Priority Date: 12/31/2002
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Doxsee, Daniel, McNulty, Thomas, Stokes, Edward, Buckley, Donald Jr.
• Granted Patent: US 6,917,057 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• 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 33/508 having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material
• CPC Class Codes: H01L 33/54 having a particular shape

Abstract

A light emitting device comprised of a light emitting diode on a mounting surface, the light emitting diode includes a substrate layer and at least one active region. A resilient substantially transparent and substantially phosphor free polymer layer extends from the mounting surface to above at least one quarter of a height of the substrate layer but below a top surface of the light emitting diode. A second phosphor containing layer extends from the phosphor free polymer layer to above the top surface of the light emitting diode.

Claims

1. A light emitting device comprised of a light emitting diode on a mounting surface, said light emitting diode including a substrate layer comprised of silicon carbide and at least one active region, at least one resilient substantially transparent and substantially phosphor free polymer layer extending from said mounting surface to above at least one quarter of a height of the substrate layer and below a top surface of the light emitting diode, and at least a second layer containing phosphor extending from said phosphor free polymer layer to a height above a top surface of said light emitting diode.

2. The light emitting device of claim 1 wherein said mounting surface comprises a curved reflector.

3. The light emitting device of claim 1 wherein said polymer is selected from silicone, epoxy or hybrids thereof.

4. The light emitting device of claim 1 wherein said material containing said phosphor is selected from silicon, epoxy, or hybrid thereof, or volatile organic liquids or semi-liquids.

5. The light emitting device of claim 1 wherein said substrate has a height of at least 150 μ

m.

6. The light emitting device of claim 1 wherein said active region comprises at least gallium and nitride.

7. The light emitting device of claim 1 wherein said LED emits lights between 360 and 420 nanometers.

8. The light emitting device of claim 1 further comprising an encapsulant layer.

9. The light emitting device wherein said phosphor is selected from TAG:

Ce, YAG;

Ce and mixtures or derivatives thereof (i.e Ga for Al or Gd for Y or Gd for Tb compositional substitutions).

10. A method of manufacturing a light emitting device comprising mounting a light emitting diode on a surface, said light emitting diode having a substrate layer and at least one active region, providing an electrical connection to said light emitting diode, depositing a substantially transparent and substantially phosphor free polymer adjacent said mounting surface to above at least one quarter of a height of the substrate layer and below a top surface of the light emitting diode, and depositing at least a second layer containing phosphor disposed in a carrier material on said phosphor free polymer layer to above a top surface of said light emitting diode.

11. The method of claim 10 wherein said substrate layer is comprised of SiC.

12. The method of claim 10 wherein said mounting surface comprises a curved reflector.

13. The method of claim 10 wherein said polymer and said carrier material are selected from silicone, epoxy or hybrids thereof.

14. The method of claim 10 wherein said carrier material is selected from silicone, epoxy, or hybrid thereof or volatile organic liquids or semi-liquids or mixtures thereof.

15. The method claim 10 wherein said substrate has a height of at least 150 μ

m.

16. The method of claim 10 wherein said active region includes at least gallium and nitride.

17. The method of claim 10 wherein said LED emits lights between 360 and 420 nanometers.

18. The method of claim 10 further comprising depositing an encapsulant layer above said phosphor containing carrier material.

19. The method of claim 10 wherein said phosphor free polymer is least partially cured before depositing said carrier material.

20. A light emitting device comprised of a light emitting diode on a mounting surface, said light emitting diode including a substrate layer, a substantially transparent and substantially phosphor free polymer layer extending from said mounting surface to above at least one quarter of a height of the substrate layer and below a top surface of the light emitting diode, and a phosphor containing layer extending from said phosphor free polymer layer to a height above the top surface of said light emitting diode.