Method of applying light-converting material and device thereof
View Patent ↗A light emitting device having a die that includes a light source that generates light of a first wavelength and a layer of phosphor particles covering the die is disclosed. The phosphor particles convert a portion of the light of the first wavelength to light of a second wavelength. The light source can be fabricated by attaching the light source to a substrate, and converting the light source by applying a light converting layer that includes a volatile carrier material and particles of a phosphor that convert light of the first wavelength to light of the second wavelength over the light source. The volatile carrier material is then caused to evaporate leaving a layer of the phosphor particles over the light source. A binder material can be incorporated in the volatile carrier for binding the phosphor particles to one another after the volatile carrier material is evaporated.
1. A method for fabricating a light emitting device comprising:
attaching a light source that generates light of a first wavelength to a substrate;
attaching a reflecting cup to said substrate, said reflecting cup comprising reflective sidewalls, said die being located in said cup such that a portion of said light generated by said light source is reflected from said cup;
applying a light converting layer comprising a volatile carrier material and particles of a phosphor that convert light of said first wavelength to light of a second wavelength over said die; and
causing said volatile carrier material to evaporate thereby leaving a conformal layer of phosphor particles covering said light source and in direct contact therewith, said phosphor particles converting at least a portion of said light of said first wavelength to light of a second wavelength, said layer having a substantially uniform thickness of less than 100 μm over said light source, said layer of phosphor particles covering a portion of said reflective sidewalls.
2. The method of claim 1 wherein said light converting layer comprises a binder material for binding said phosphor particles to one another when said volatile carrier material is evaporated.
3. The method of claim 2 wherein said carrier material evaporates at a temperature less than 200° C.
4. The method of claim 2 wherein said binder material also causes said phosphor particles to bind to said light source and a portion of said substrate.
5. The method of claim 4 wherein said binder material comprises a polymer comprising acrylic resin, di-butyl phathalate, diacetone alcohol, or tetra ethyl orthosilicate.
6. The method of claim 1 wherein said layer of said phosphor particles is less than 100 μm thick over said light source.
7. The method of claim 1 wherein said carrier material comprises epoxy resins, silicone, polyurethanes, polyvinyl acetates, cyanoacrylate, phathalate, glass, aluminum nitride or silicone dioxide.