LIGHT-EMITTING DIODE WITH LIGHT-CONVERSION LAYER

• US 20100155755A1
• Filed: 12/24/2008
• Published: 06/24/2010
• Est. Priority Date: 12/24/2008
• Status: Active Grant

• Current Assignee: Ledengin, Inc. (Ams-Osram AG)
• Original Assignee: Ledengin, Inc. (Ams-Osram AG)
• Inventors: DONG, YI
• Granted Patent: US 8,507,300 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• 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

Abstract

A method for making a lighting apparatus includes providing a substrate and disposing a light-emitting diode overlying the substrate. The light-emitting diode has a top surface oriented away from the substrate and a plurality of side surfaces. A light-conversion material is provided that includes a substantially transparent base material and a wave-shifting material dispersed in the base material. The concentration of the wave-shifting material can be at least 30%. In an embodiment, the concentration of the wave-shifting material can be approximately 50% or 70%. A predetermined amount of the light-conversion material is deposited on the top surface of the light-emitting diode while the side surfaces are maintained substantially free of the light-conversion material.

Claims

1. A method for making a lighting apparatus, the method comprising:

providing a substrate;

disposing a light-emitting diode overlying the substrate, the light-emitting diode having a top surface oriented away from the substrate and a plurality of side surfaces;

providing a light-conversion material that includes a substantially transparent base material and a wave-shifting material dispersed in the base material, a concentration of the wave-shifting material being at least 30%; and

depositing a predetermined amount of the light-conversion material on the top surface of the light-emitting diode while maintaining the side surfaces substantially free of the light-conversion material.

2. The method of claim 1 further comprising allowing the wave-shifting material to settle to a bottom portion of the light-conversion material on the top surface of the light-emitting diode.

3. The method of claim 1 wherein the substrate has a recess in a front side thereof, wherein the light-emitting diode is disposed in the recess.

4. The method of claim 1 further comprising subjecting the substrate, the light-emitting diode, and the light-conversion material to a curing process.

5. The method of claim 1 wherein the light-conversion material is deposited using a syringe or a needle.

6. The method of claim 1 wherein the wave-shifting material comprises particles having an average diameter of 2 μ

m or larger.

7. The method of claim 1 wherein the wave-shifting material comprises phosphor particles.

8. The method of claim 7 further comprising allowing the phosphor particles to settle to a bottom portion of the light-conversion material on the top surface of the light-emitting diode.

9. The method of claim 7 wherein the predetermined amount of light-conversion material comprises approximately 0.1 mg of phosphor particles.

10. The method of claim 7 wherein the transparent base material comprises silicone.

11. The method of claim 7 wherein the phosphor particles are characterized by an average diameter of 2 μ

m or larger.

12. The method of claim 7 wherein the light-conversion material has a phosphor concentration of approximately 70%.

13. The method of claim 1 wherein the substrate includes a plurality of recesses, and wherein:

disposing the light-emitting diode includes disposing a light-emitting diode in each of the plurality of recesses, each light-emitting diode having a top surface and a plurality of side surfaces; and

disposing the predetermined amount of the light-conversion material includes depositing a predetermined amount of the light-conversion material on the respective top surfaces of at least two different ones of the light-emitting diodes while maintaining the side surfaces of each light-emitting diode substantially free of the light-conversion material.

14. The method of claim 13 wherein the depositing is performed sequentially for each of the at least two different ones of the light-emitting diodes.

15. The method of claim 13 wherein the depositing is performed in parallel for a plurality of the light-emitting diodes.

16. The method of claim 15 wherein the depositing is performed using a plurality of syringes.

17. The method of claim 15 wherein the depositing is performed using a device with multiple needle heads.

18. The method of claim 1 wherein the light-emitting diode is adapted to emit light from its top surface and to emit substantially no light from its side surfaces.

19. The method of claim 1 further comprising coating the light-emitting diode with a thin layer of a transparent material before depositing the source material.

20. The method of claim 19 wherein the transparent material comprises silicone.

21. The method of claim 1 wherein the light-emitting diode is adapted to emit blue light and the wave-shifting material comprises yellow phosphor particles.

22. The method of claim 1 wherein the wave-shifting material comprises a mixture of different types of phosphor particles.

23. A method for making a lighting apparatus, the method comprising:

providing a substrate;

disposing at least a first light-emitting diode and a second light-emitting diode overlying the substrate, each of the first and the second light-emitting diodes having a top surface oriented away from the substrate and a plurality of side surfaces;

providing a first phosphor-containing material having a phosphor concentration of at least 30%

providing a second phosphor-containing material having a phosphor concentration of at least 30%;

depositing a first predetermined amount of the first phosphor-containing material on the top surface of the first light-emitting diode while maintaining the side surfaces substantially free of the phosphor-containing material; and

depositing a second predetermined amount of the second phosphor-containing material on the top surface of the second light-emitting diode while maintaining the side surfaces substantially free of the phosphor-containing material.

24. The method of claim 23 wherein the first light-emitting diode and the first phosphor-containing material are configured to produce light of a first color, and the second light-emitting diode and the second phosphor-containing material are configured to produce light of a second color that is different from the first color.

25. The method of claim 23 wherein the phosphor particles are characterized by diameters of 2 μ

m or larger.

26. The method of claim 23 wherein the phosphor-containing material is deposited using a syringe or a needle.

27. A lighting apparatus, comprising:

a light-emitting diode having a top surface capable of emitting light and a plurality of side surfaces; and

a light-conversion layer overlying the top surface of the light-emitting diode, the side surfaces of the light-emitting diode being substantially free of the light-conversion layer, the light-conversion layer including a substantially transparent base material and a wave-shifting material, a concentration of the wave-shifting material being at least 30%.

28. The apparatus of claim 27 wherein the light-conversion layer is configured such that the lighting apparatus provides substantially uniform white light.

29. The apparatus of claim 27 wherein the light-emitting diode is configured such that during operation substantially no light is emitted from the side surfaces thereof.

30. The apparatus of claim 27 wherein the wave-shifting material comprises particles having an average diameter of 2 μ

m or larger.

31. The apparatus of claim 27 further comprising a substrate having the a recess in a front side thereof, wherein the light-emitting diode is disposed in the recess with the top surface oriented away from the substrate.

32. The apparatus of claim 27 wherein the wave-shifting material is located substantially in a bottom portion of the light-conversion material on the top surface of the light-emitting diode.

33. The apparatus of claim 27 wherein the concentration of the wave-shifting material is approximately 50%.