Color control by alteration of wavelenght converting element
View Patent ↗A light emitting device is produced by depositing a layer of wavelength converting material over the light emitting device, testing the device to determine the wavelength spectrum produced and correcting the wavelength converting member to produce the desired wavelength spectrum. The wavelength converting member may be corrected by reducing or increasing the amount of wavelength converting material. In one embodiment, the amount of wavelength converting material in the wavelength converting member is reduced, e.g., through laser ablation or etching, to produce the desired wavelength spectrum.
1. A method for fabricating a light emitting diode (LED) device comprising:
providing an LED die on a support substrate;
providing an optical element affixed over the LED die;
depositing a wavelength converting material as a layer over the optical element;
energizing the LED die after depositing the wavelength converting material as a layer over the optical element;
optically testing a light emission from the LED die and wavelength converting material;
comparing the light emission to a desired light emission; and
after comparing the light emission to a desired light emission, depositing additional wavelength converting material over the optical element if such additional wavelength converting material is needed to achieve the desired light emission.
2. The method of claim 1 wherein the wavelength converting material is a phosphor.
3. The method of claim 1 wherein the step of depositing the wavelength converting material comprises spray coating the wavelength converting material over the optical element.
4. The process of claim 1 wherein the optical element is a lens having a rounded top surface.
5. The process of claim 1 wherein the optical element is a lens and wherein the step of providing the optical element affixed over the LED die comprises pre-forming the lens and affixing the lens to a top surface of the LED die.
6. The method of claim 1 wherein the step of comparing the light emission to the desired light emission comprises comparing a correlated color temperature (CCT) of the light emission to a target CCT.
7. The method of claim 1 wherein the step of depositing the wavelength converting material comprises spray coating the wavelength converting material over the optical element, the method further comprising:
stopping the spray coating of the wavelength converting material prior to optically testing the light emission; and
wherein the step of depositing additional wavelength converting material over the optical element comprises resuming the spray coating of the wavelength converting material if such additional wavelength converting material is needed to achieve the desired light emission.
8. The method of claim 7 wherein the step of providing the LED die on the support substrate comprises providing a plurality of LED dies on the support substrate, and wherein the step of spray coating the wavelength converting material over the optical element comprises spray coating the wavelength converting material over all the LED dies simultaneously.
9. The method of claim 1 wherein the step of providing the LED die on the support substrate comprises providing a plurality of LED dies on the support substrate, and wherein the step of depositing the wavelength converting material comprises depositing the wavelength converting material simultaneously over all the LED dies on the support substrate.
10. The method of claim 1 further comprising singulating the support structure after the step of depositing additional wavelength converting material over the optical element.
11. The method of claim 1 wherein the step of providing the LED die on the support substrate comprises providing an LED wafer on the support substrate prior to singulating the LED wafer.
12. The method of claim 1 wherein the support substrate is a submount having electrodes connected to electrodes on the LED die.
13. The method of claim 1 wherein the wavelength converting material forms an outer layer of a completed LED device.