Phosphor coating systems and methods for light emitting structures and packaged light emitting diodes including phosphor coating

• US 8,058,088 B2
• Filed: 01/15/2008
• Issued: 11/15/2011
• Est. Priority Date: 01/15/2008
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Jackson, Mitchell, Cannon, Nathaniel O.
• Primary Examiner(s): Tran; Minh-Loan T
• Application Number:
  US12/014,404
• Publication Number:
  US 20090179213A1
• Time in Patent Office: 1,400 Days
• Field of Search: 438/48, 438/65, 438/69, 257/98, 257/100, 257/E33.061, 257/E33.067
• US Class Current: 438/48
• CPC Class Codes: B05B 7/066 with an inner liquid outlet surrounded by at least one annular gas outlet
• 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 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body

Abstract

Methods are disclosed including applying a layer of binder material onto an LED structure. A luminescent solution including an optical material suspended in a solution is atomized using a flow of pressurized gas, and the atomized luminescent solution is sprayed onto the LED structure including the layer of binder material using the flow of pressurized gas.

Claims

1. A method, comprising:

applying a layer of binder material onto an LED structure; and

atomizing a luminescent solution comprising an optical material suspended in a solution using a flow of pressurized gas and spraying the atomized luminescent solution, as a step that is separate from applying the layer of the binder material, onto the LED structure including the layer of binder material using the flow of pressurized gas.

2. The method of claim 1, wherein spraying the luminescent solution comprises spraying the luminescent solution with an air pressurized spray system.

3. The method of claim 1, wherein applying the layer of binder material comprises spraying the binder material with an air pressurized spray system.

4. The method of claim 1 wherein the luminescent solution comprises wavelength conversion particles suspended in a volatile solvent, the method further comprising evaporating a solvent from the luminescent solution to provide a layer of wavelength conversion particles on the LED structure.

5. The method of claim 4, wherein the LED structure comprises an LED wafer, the method further comprising singulating the LED wafer into a plurality of LED chips after applying the layer of binder material and after evaporating the solvent from the luminescent solution.

6. The method of claim 1, wherein the luminescent solution comprises wavelength conversion particles suspended in a nonvolatile solvent, the method further comprising curing the nonvolatile solvent to provide a layer including the wavelength conversion particles on the LED structure.

7. The method of claim 1, wherein the LED structure comprises an LED chip having a top surface and a wirebond pad on the top surface, the method further comprising bonding a wire to the wirebond pad before spraying the luminescent solution onto the LED chip.

8. The method of claim 1, wherein the LED structure comprises an LED chip having a top surface and a wirebond pad on the top surface, the method further comprising mounting the LED within an optical cavity of an LED package before spraying the luminescent solution onto the LED chip.

9. The method of claim 8, further comprising:

curing the binder layer; and

dispensing an encapsulant material into the optical cavity over the LED chip, thereby covering the LED chip including the layer of phosphor and the layer of cured binder material with the encapsulant material.

10. A method, comprising:

applying a layer of binder material onto an LED structure; and

atomizing a luminescent solution comprising an optical material suspended in a solution using a flow of pressurized gas and spraying the atomized luminescent solution onto the LED structure including the layer of binder material using the flow of pressurized gas;

wherein the luminescent solution comprises wavelength conversion particles suspended in a volatile solvent, the method further comprising evaporating a solvent from the luminescent solution to provide a layer of wavelength conversion particles on the LED structure, wherein evaporating the solvent from the luminescent solution comprises baking the luminescent solution and/or exposing the luminescent solution to ultraviolet light.

11. A method, comprising:

applying a layer of binder material onto an LED structure; and

atomizing a luminescent solution comprising an optical material suspended in a solution using a flow of pressurized gas and spraying the atomized luminescent solution onto the LED structure including the layer of binder material using the flow of pressurized gas;

energizing the LED structure to cause the LED structure to emit light;

testing optical characteristics of the light emitted by the LED structure; and

if the optical characteristics are not within a predetermined binning threshold, spraying additional luminescent solution comprising a phosphor suspended in a solution onto the LED structure, evaporating the additional luminescent solution to provide an additional layer of phosphor on the LED structure, and applying an additional layer of binder material onto the LED structure.

12. A method, comprising:

applying a layer of binder material onto an LED structure; and

atomizing a luminescent solution comprising an optical material suspended in a solution using a flow of pressurized gas and spraying the atomized luminescent solution onto the LED structure including the layer of binder material using the flow of pressurized gas;

wherein the LED structure comprises an LED wafer, the method further comprising;

forming a plurality of electrical contacts on a surface of the LED wafer; and

forming a plurality of sacrificial patterns on respective ones of the plurality of electrical contacts;

wherein applying the layer of binder material comprises applying the layer of binder material to the sacrificial patterns and onto exposed surfaces of the LED wafer between the sacrificial patterns.

13. The method of claim 12, further comprising removing the sacrificial patterns and the portion of the binder material on the sacrificial patterns to expose the plurality of electrical contacts.

14. The method of claim 12, wherein the sacrificial patterns do not completely cover top surfaces of the electrical contacts, so that the applied binder material is at least partially on portions of the top surfaces of the electrical contacts.

15. A method of forming a semiconductor light emitting device, comprising:

applying a layer of binder material onto an LED structure;

atomizing a luminescent solution comprising an optical material suspended in a solution using a flow of pressurized gas and spraying the atomized luminescent solution, as a step that is separate from applying the layer of the binder material, onto the LED structure including the layer of binder material using the flow of pressurized gas to provide a first layer of optical material;

curing the layer of binder material;

testing a light emission characteristic of the LED structure; and

if the light emission characteristic of the LED structure is not acceptable,

applying a second layer of optical material on the LED structure.

16. The method of claim 15, wherein the first layer of optical material comprises a first phosphor particle that is configured to emit light having a first wavelength in response to light emitted by the LED structure, and wherein the second layer of optical material comprises a second phosphor particle that is configured to emit light having a second wavelength, different from the first wavelength, in response to light emitted by the LED structure.