Phosphor distribution in LED lamps using centrifugal force

• US 8,167,674 B2
• Filed: 12/14/2007
• Issued: 05/01/2012
• Est. Priority Date: 12/14/2007
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Hussell, Christopher P., Emerson, David T.
• Primary Examiner(s): Ton, Toan
• Assistant Examiner(s): Hanley, Britt D
• Application Number:
  US11/956,989
• Publication Number:
  US 20090153022A1
• Time in Patent Office: 1,600 Days
• Field of Search: None
• US Class Current: 445/23
• CPC Class Codes: H01L 2224/32013 the layer connector being larger than the bonding area, e.g. bond pad
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/32257 the layer connector connecting to a bonding area disposed in a recess of the surface of the item
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/50 Wavelength conversion elements

Abstract

A method of manufacturing an LED lamp is disclosed. The method includes admixing an uncured curable liquid resin and a phosphor, dispensing the uncured admixture on an LED chip, centrifuging the chip and the admixture to disperse the phosphor particles in the uncured resin, and curing the resin while the phosphor particles remain distributed.

Claims

1. A method of manufacturing an LED lamp comprising:

admixing an uncured curable liquid resin and a phosphor to create an admixture;

dispensing the admixture on an LED chip; and

centrifuging the chip and the admixture such that a centrifugal force normal to a surface on which the LED chip is mounted causes the phosphor particles to settle at a desired position with respect to the LED chip.

2. A method according to claim 1 further comprising curing the resin while the phosphor particles remain at the desired position.

3. A method according to claim 1 wherein the step of centrifuging the chip and the admixture comprises centrifuging the chip and the admixture in a centrifuge.

4. A method according to claim 1 comprising admixing the resin with a phosphor that down-converts frequencies in the blue portion of the visible spectrum into frequencies in the yellow portion of the visible spectrum.

5. A method according to claim 1 comprising admixing the resin with a phosphor selected from the group of phosphors that emit in the green and red portions of the visible spectrum.

6. A method according to claim 1 comprising admixing the resin with a blend of phosphors that emit in different portions of the visible spectrum.

7. A method according to claim 1 comprising admixing the resin with a yttrium aluminum garnet (YAG) phosphor.

8. A method according to claim 1 comprising placing an LED chip that emits in the blue portion of the visible spectrum into a cup with the admixed resin and phosphor.

9. A method according to claim 1 comprising admixing a polysiloxane resin with the phosphor.

10. A method according to claim 1 comprising adding a lens to the lamp after the centrifuging step.

11. A method according to claim 1 comprising:

placing a cup in a centrifuge; and

thereafter placing the chip in the cup; and

thereafter placing the admixture in the cup with the chip; and

thereafter centrifuging the cup and its contents to distribute the phosphor.

12. A method according to claim 1 comprising:

placing the chip into a cup; and

thereafter placing the cup into a centrifuge; and

thereafter placing the admixture in the cup; and

thereafter centrifuging the cup and its contents to distribute the phosphor.

13. An LED lamp produced by the method of claim 1.

14. An LED lamp according to claim 13 wherein said liquid resin is a polysiloxane resin.

15. An LED lamp according to claim 13 wherein the phosphor downconverts frequencies in the blue portion of the visible spectrum into frequencies in the yellow portion of the visible spectrum.

16. An LED lamp according to claim 15 wherein the phosphor comprises yttrium aluminum garnet.

17. An LED lamp according to claim 15 wherein the phosphor is selected from the group consisting of red-emitting, blue-emitting and green-emitting phosphors.

18. An LED lamp according to claim 13 wherein the LED chip has an active portion selected from the Group III nitride material system.

19. A method of manufacturing an LED lamp comprising:

admixing an uncured polysiloxane resin and a phosphor that emits predominantly in the yellow portion of the spectrum when excited by frequencies from the blue portion of the visible spectrum to create an admixture;

placing the uncured admixture and an LED chip formed from the Group III nitride material system and that emits in the blue portion of the visible spectrum into a reflector;

centrifuging the reflector and the admixture such that a centrifugal force causes the phosphor particles to settle at a desired position proximate to the LED chip in the uncured polysiloxane resin; and

curing the resin while the phosphor particles remain settled proximate to the LED chip.

20. A method according to claim 19 comprising admixing the polysiloxane resin with a yttrium aluminum garnet phosphor.

21. A method according to claim 19 comprising admixing the polysiloxane resin and the phosphor with the phosphor present in an amount of between about 1 and 50 percent based on the weight of the resin.

22. A method according to claim 19 comprising admixing phosphor particles with an average particle size of between about 0.001 microns and 20 microns per particle.

23. A method according to claim 19 comprising admixing the phosphor particles with a polysiloxane resin having a starting viscosity of between about 10 and 100,000 millipascal-seconds.