Using electrophoresis to produce a conformally coated phosphor-converted light emitting semiconductor
First Claim
1. A method of conformally coating a light emitting semiconductor structure with phosphor, said method comprising:
- providing a submount having a conductive region;
electrically coupling a light emitting semiconductor structure to said conductive region;
applying a first bias voltage to charged phosphor particles in a solution; and
applying a second bias voltage to said conductive region to induce said phosphor particles to substantially conformally deposit on at least one surface of said light emitting semiconductor structure.
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Accused Products
Abstract
Presented is a method of conformally coating a light emitting semiconductor structure with a phosphor layer to produce a substantially uniform white light. A light emitting semiconductor structure is coupled to a submount, a first bias voltage is applied to the submount, and a second bias voltage is applied to a solution of charged phosphor particles. The charged phosphor particles deposit on the conductive surfaces of the light emitting semiconductor structure. If the light emitting semiconductor structure includes a nonconductive substrate, the light emitting semiconductor structure is coated with an electroconductive material to induce phosphor deposition. The electrophoretic deposition of the phosphor particles creates a phosphor layer of uniform thickness that produces uniform white light without colored rings.
325 Citations
28 Claims
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1. A method of conformally coating a light emitting semiconductor structure with phosphor, said method comprising:
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providing a submount having a conductive region;
electrically coupling a light emitting semiconductor structure to said conductive region;
applying a first bias voltage to charged phosphor particles in a solution; and
applying a second bias voltage to said conductive region to induce said phosphor particles to substantially conformally deposit on at least one surface of said light emitting semiconductor structure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
depositing strips of a first layer of insulating material on said submount, said strips separated by gaps;
forming a conductive cathode layer and a conductive anode layer on said first layer of insulating material and on said gaps, said conductive cathode layer and said conductive anode layer being separated by a window;
coating said window, said conductive cathode layer, and said conductive anode layer with a second layer of insulating material, leaving uncoated a part of said cathode layer and said anode layer for electric connections; and
covering said uncoated part with a nonconductive material.
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7. The method of claim 6, wherein said coupling comprises:
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forming a conductive connective means on said cathode layer and said anode layer; and
bonding said light emitting semiconductor structure to said conductive connective means.
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8. The method of claim 6, wherein said first layer and said second layer of insulating material comprises at least one of AlnOm, SiOx, SixNy, polyimide, and poly methyl methacrylate.
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9. The method of claim 6, wherein said nonconductive material comprises a photoresist.
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10. The method of claim 1, wherein said phosphor particles comprise a strontium sulfide compound.
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11. The method of claim 1, wherein said phosphor particles comprise a yttrium aluminum garnet compound doped with at least one of gadolinium, cerium, and praseodymium.
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12. The method of claim 1, wherein said phosphor particles comprise a strontium thiogallate compound.
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13. The method of claim 1, wherein said phosphor particles comprise a polymer containing an organic luminescent dye.
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14. The method of claim 1, wherein said phosphor particles are for being activated by light emitted by said light emitting semiconductor structure to produce light of wavelengths that in combination appear white to the human eye.
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15. The method of claim 1, wherein said solution comprises a transparent binder material for securing the adhesion of said phosphor particles to said conductive region, said transparent binder material having a refractive index of at least 1.4.
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16. The method of claim 1, wherein said solution comprises a charging agent for charging said phosphor particles.
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17. The method of claim 1, further comprising infusing a transparent binder material into a matrix of said phosphor particles deposited on said conductive region, said binder material aiding the adhesion of said phosphor particles onto said conductive region and having a refractive index of at least 1.4.
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18. The method of claim 1, wherein said light emitting semiconductor structure comprises:
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a nonconductive substrate; and
a layer of transparent electroconductive material, wherein said electroconductive material is deposited by a method comprising;
mounting a wafer on a tape;
cutting said wafer into a plurality of light emitting semiconductor structures;
separating each of said plurality of light emitting semiconductor structures from a neighboring light emitting semiconductor structure, creating a gap between neighboring light emitting semiconductor structures; and
depositing said layer of electroconductive material on said plurality of light emitting semiconductor structures.
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19. The method of claim 18, wherein the electric conductivity of said layer of electroconductive material is between the electric conductivity of said phosphor particles and the electric conductivity of said light emitting semiconductor structure.
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20. The method of claim 18, wherein said electroconductive material comprises antimony tin oxide.
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21. The method of claim 18, wherein said layer is about 50 nm in thickness.
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22. The method of claim 1, further comprising:
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depositing a layer of electroconductive material on surfaces of said light emitting semiconductor structure and on surfaces of said submount; and
preventing phosphor deposition on a part of said layer of electroconductive material by coating with a nonconductive material.
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23. The method of claim 22, wherein said depositing comprises moistening the surface of said light emitting semiconductor structure with a solution comprising antimony tin oxide.
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24. The method of claim 1 wherein said second bias voltage induces said phosphor particles to substantially conformally deposit on a first surface and a second surface of said light emitting semiconductor structure, wherein the first surface is not parallel to the second surface.
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25. A method of conformally coating a light emitting semiconductor structure with phosphor, said method comprising:
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providing a light emitting semiconductor structure having a first surface and a second surface, the light emitting semiconductor structure having an anode and a cathode connected to a first bias voltage;
applying a second bias voltage to a solution of charged phosphor; and
immersing said light emitting semiconductor structure in said solution to substantially conformally coat at least a portion of said first surface and said second surface of said light emitting semiconductor structure with said phosphor particles.- View Dependent Claims (26, 27, 28)
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Specification