Fabrication for precise line-bond control and gas diffusion between LED components
A light emitting device includes an LED having a (e.g., top) light output surface, a ceramic phosphor, and an adhesive layer positioned to attach the top of the LED to the ceramic phosphor. In one embodiment the adhesive layer is composed of multiple separate patches (regions) that define at least one channel therebetween, with the channel being open to an environment to permit oxygen permeation. The adhesive layer can be applied by a patternable dispensing system.
1. A light emitting device comprising:
a semiconductor light emitting diode (LED) comprising a light output surface;
a phosphor comprising a first surface; and
a high refractive index adhesive disposed between, in contact with, and attaching the light output surface of the LED and the first surface of the phosphor, the adhesive comprising a pressure sensitive adhesive, a temperature sensitive adhesive, a heat pressure sensitive adhesive, or a hot melt pressure sensitive adhesive, the adhesive arranged as two or more separate regions on the light output surface of the LED that define at least one channel therebetween, the channel located between the light output surface of the LED and the first surface of the phosphor and open to an environment external to the light emitting device,
in operation, the channel allowing transport of gases through the channel.
2. The light emitting device of claim 1 , wherein the adhesive has a uniform thickness across each of the multiple separate regions.
3. The light emitting device of claim 2 , wherein the adhesive has a uniform thickness of less than 5 microns.
4. The light emitting device of claim 2 , wherein the adhesive has a uniform thickness of between 1 micron and 5 microns.
5. The light emitting device of claim 1 , wherein the channel has a width between 10 microns and 50 microns defined by the separate regions of the adhesive.
6. The light emitting device of claim 1 , wherein the channel extends across the two or more separate regions of adhesive from an edge of the LED to an opposite edge of the LED.
7. The light emitting device of claim 1 , wherein the channel extends through one of the two or more separate regions of adhesive from an edge of the LED to near center of the one region of adhesive.
8. The light emitting device of claim 1 , wherein the separate regions of the adhesive define multiple intersecting channels.
9. The light emitting device of claim 1 , wherein the separate regions of the adhesive define one or more non-linear channels.
10. The light emitting device of claim 1 , wherein the separate regions of the adhesive define multiple channels with varying widths.
11. The light emitting device of claim 1 , wherein the phosphor is a ceramic phosphor.
12. The light emitting device of claim 1 , wherein the adhesive comprises a polysiloxane adhesive.
13. The light emitting device of claim 1 , wherein the adhesive comprises a pressure sensitive adhesive.
14. The light emitting device of claim 1 , wherein the adhesive comprises a temperature sensitive adhesive.
15. The light emitting device of claim 1 , wherein the adhesive comprises a heat pressure sensitive adhesive.
16. The light emitting device of claim 1 , wherein the adhesive comprises a hot melt pressure sensitive adhesive.
17. A light emitting device comprising:
a semiconductor light emitting diode (LED) comprising a light output surface;
a phosphor comprising a first surface; and
a high refractive index adhesive disposed between, in contact with, and attaching the light output surface of the LED and the first surface of the phosphor, the adhesive comprising a pressure sensitive adhesive, a temperature sensitive adhesive, a heat pressure sensitive adhesive, or a hot melt pressure sensitive adhesive, the adhesive arranged as two or more separate regions on the light output surface of the LED that define at least one channel therebetween, the channel located between the light output surface of the LED and the first surface of the phosphor and is filled with a material having a higher gas permeability than the adhesive,
in operation, the channel allowing transport of gases through the channel.