Integrated reflector and thermal spreader and thermal spray fabrication method
View Patent ↗A low-cost integrated reflector and heat spreader for high-density high power solid-state (e.g., LED) lighting arrays includes a base structure onto which is applied a sacrificial material. A relatively thick thermal spray coating is applied over the base structure and sacrificial material. The sacrificial material is removed. A channel(s) is thereby provided within the thermal spray coating layer and in physical contact with the base structure. The channel may be filled with a cooling fluid. A pulsating heat pipe heat spreader may thereby be provided. A reflective material may be provided either over another surface of the base structure or alternatively over the thermal spray coating layer to provide a surface for reflecting and directing light emitted from a solid state light source that may be secured to the integrated reflector and heat spreader.
1. A method for fabricating an optical element comprising:
forming over a first surface of a base structure having a light emitter receiving region formed therein a pattern of sacrificial material;
applying a thermal spray coating over said first surface of said base structure and said sacrificial material to thereby form a thermal spray coating layer except over said light emitter receiving region; and
removing said sacrificial material to thereby leave a substantially enclosed channel within said thermal spray coating layer, said channel configured to receive and retain a cooling medium therein, said channel further configured in a serpentine pattern extending between a hot region of said base structure proximate said light emitter region and a cold region of said base structure spaced away from said hot region.
2. The method of claim 1 , further comprising forming a sealable port in said channel and filling said channel through said port with a cooling fluid.
3. The method of claim 2 , wherein said cooling fluid is selected from the group consisting of: water, saturated steam, alcohol, propylene glycol, and ethylene glycol.
4. The method of claim 2 , wherein said channel thereby forms a pulsating heat pipe thermal spreader.
5. The method of claim 1 , wherein said thermal spraying comprises spraying a molten metal powder onto the base structure.
6. The method of claim 1 , wherein said thermal spraying comprises powder coating a polymer onto the base structure.
7. The method of claim 3 , further comprising applying a reflective coating to a second surface of said base structure opposite said first surface.
8. The method of claim 7 , wherein said reflective coating is deposited by way of physical vapor deposition.
9. The method of claim 7 , further comprising securing a solid-state light emitting device to said base structure at said light emitter receiving region.
10. The method of claim 1 , further comprising forming a plurality of discrete patterns of sacrificial material over said first surface of said base structure, whereby following said applying a thermal spray coating and removing said sacrificial material a plurality of non-interconnected channels are formed in said thermal spray coating layer.
11. The method of claim 10 , further comprising forming a sealable port in each said channel, and filling each said channel through its port with a cooling fluid.
12. The method of claim 1 , wherein said sacrificial material is formed to have serpentine shape and said channel forms a micro heat pipe.
13. The method of claim 1 , wherein said sacrificial material is formed to have a first cross-section shape over a first portion of said base structure closest to said light emitter receiving region and a second different cross-section shape over a second portion of said base structure farthest from said light emitter receiving region.