Phosphor converter structures for thin film packages and method of manufacture
Light emitting devices (LEDs) and methods of manufacturing LEDs are described. A method includes providing a layer of a wavelength converting material on a temporary tape. The wavelength converting material includes at least a binder or matrix material, particles of a non-luminescent material, and phosphor particles and has a concentration of 60%-90% by volume particles of the non-luminescent material and phosphor particles. The layer of the wavelength converting material is separated on the temporary tape to form multiple wavelength converting structures, which are provided on an array type frame. Heat and pressure are applied to the wavelength converting structures on the array type frame.
1. A method of manufacturing a light emitting device (LED), the method comprising:
providing a layer of a wavelength converting material, the wavelength converting material comprising a binder or matrix material, particles of a non-luminescent material, and phosphor particles, the wavelength converting material having a concentration of greater than 60% by volume of the non-luminescent material and phosphor particles;
separating the layer of the wavelength converting material into a plurality of wavelength converting structures, one of the plurality of wavelength converting structures having a first surface, a second surface opposite the first surface, and side surfaces created by the separation;
placing the one wavelength converting structure in a frame having an interior area defined by one or more surfaces of the frame;
applying heat to and compressing the one wavelength converting structure to cause the wavelength converting material in the structure to flow, to cover the interior area, and to contact a surface of the frame to create a new wavelength converting structure side surface
after applying heat to and compressing the one wavelength converting structure, attaching a light emitting die to the one wavelength converting structure to form a light emitting device.
2. The method of claim 1 , wherein the new side surface has a roughness of less than 100 nm.
3. The method of claim 1 , wherein attaching a light emitting die to the one wavelength converting structure comprises attaching the light emitting die without using adhesive.
4. The method of claim 1 , comprising coating the new side surface with a thin film of a non-metallic reflector.
5. The method of claim 4 , wherein the non-metallic reflector is a Bragg reflector with a thickness of 1-10 microns.
6. The method of claim 4 , wherein both the wavelength converting material and the non-metallic reflector have a coefficient of thermal expansion between 6 and 20 ppm.
7. The method of claim 1 , wherein the binder or matrix material is silicone and the non-luminescent material is silica (SiO 2 ).
8. The method of claim 1 , wherein applying heat and compressing further comprises heating the one wavelength converting structure to a temperature of between 50° C. and 90° C. and subjecting the one wavelength converting structure to a pressure of between 0.7 and 0.8 Mpa.
9. The method of claim 1 , wherein the binder or matrix material and the non-luminescent material are chosen at least in part based on their indices of refraction.
10. The method of claim 1 , wherein the separating the layer of the wavelength converting material comprises sawing the layer of the wavelength converting material.
11. The method of claim 1 , wherein the concentration of non-luminescent and phosphor particles in the wavelength converting material is greater than 70% by volume.
12. The method of claim 1 , wherein the concentration of non-luminescent and phosphor particles in the wavelength converting material is about 90% by volume.
13. The method of claim 1 , comprising before separating the layer of the wavelength converting material into the plurality of wavelength converting structures, placing the layer of the wavelength converting material on a temporary tape.
14. The method of claim 1 , wherein the frame is an array type frame.
15. The method of claim 1 , wherein the frame is adhered to a tape.
16. The method of claim 1 , wherein attaching the light emitting die to the one wavelength converting structure comprises using heat to attach the light emitting die to the one wavelength converting structure.
17. The method of claim 1 , comprising after attaching the light emitting die to the one wavelength converting structure, separating the light emitting device from the frame.