Granted Patent B2

US 7,878,232 · App. 10/887,601 · Granted Feb 1, 2011

Abstract

Claims (31)

1. A light emitting apparatus comprising:

a plurality of light emitting chips; and

a substantially isothermal printed circuit board on which the plurality of light emitting chips are disposed, the substantially isothermal printed circuit board including: (i) an electrically insulating board, (ii) printed circuitry disposed on or in the insulating board and connecting with the plurality of light emitting chips, and (iii) a heat spreader including a thermally superconducting heat transfer medium disposed in an interior volume of the heat spreader, the thermally superconducting heat transfer medium having a finite thermal conductivity at least 1500 times greater than the thermal conductivity of copper.

2. The light emitting apparatus as set forth in claim 1 , wherein the interior volume of the heat spreader comprises:

a plurality of interior volumes.

3. The light emitting apparatus as set forth in claim 1 , wherein the heat spreader comprises:

a generally planar support for the electrically insulating board, the interior volume of the heat spreader being generally planar and disposed inside the generally planar support.

4. The light emitting apparatus as set forth in claim 3 , wherein the substantially isothermal printed circuit board is a metal core printed circuit board, and the heat spreader comprises:

a metal core of the substantially isothermal printed circuit board.

5. The light emitting apparatus as set forth in claim 1 , wherein the thermally superconducting heat transfer medium is a powder-based thermally superconducting heat transfer medium disposed on surfaces of the interior volume of the heat spreader.

6. The light emitting apparatus as set forth in claim 1 , wherein the thermally superconducting heat transfer medium comprises:

a first layer comprising at least one compound selected from the group consisting of sodium peroxide, sodium oxide, beryllium oxide, manganese sesquioxide, aluminum dichromate, calcium dichromate, boron oxide, dichromate radical, and combinations thereof;

a second layer comprising at least one compound selected from the group consisting of cobaltous oxide, manganese sesquioxide, beryllium oxide, strontium chromate, strontium carbonate, rhodium oxide, cupric oxide, β-titanium, potassium dichromate, boron oxide, calcium dichromate, manganese dichromate, aluminum dichromate, dichromate radical, and combinations thereof; and

third layer comprising at least one compound selected from the group consisting of denatured rhodium oxide, potassium dichromate, denatured radium oxide, sodium dichromate, silver dichromate, monocrystalline silicon, beryllium oxide, strontium chromate, boron oxide, sodium peroxide, β-titanium, a metal dichromate, and combinations thereof.

7. The light emitting apparatus as set forth in claim 1 , wherein the heat spreader is elongated in a direction transverse to the electrically insulating board to define a post.

8. The light emitting apparatus as set forth in claim 1 , wherein the heat spreader defines a sub-mount.

9. The light emitting apparatus as set forth in claim 1 , wherein the heat spreader is laterally substantially coextensive with the electrically insulating board.

10. The light emitting apparatus as set forth in claim 1 , wherein the thermally superconducting heat transfer medium has a thermal conductivity at least 20000 times greater than the thermal conductivity of silver.

11. A light emitting apparatus comprising:

a plurality of light emitting chips;

a printed circuit board on which the plurality of light emitting chips is disposed, the printed circuit board including printed circuitry electrically interconnecting the plurality of light emitting chips; and

a thermally superconducting heat transfer medium in an enclosed volume that is in thermal communication with all of the plurality of light emitting chips, the thermally superconducting heat transfer medium having a finite thermal conductivity that is at least 1500 times larger than the thermal conductivity of copper, the thermally superconducting heat transfer medium spreading heat generated by the plurality of light emitting chips to reduce thermal non-uniformities across the printed circuit board such that the printed circuit board is a substantially isothermal printed circuit board.

12. The light emitting apparatus as set forth in claim 11 , wherein the thermally superconducting heat transfer medium comprises:

a first layer comprising at least one compound selected from the group consisting of sodium peroxide, sodium oxide, beryllium oxide, manganese sesquioxide, aluminum dichromate, calcium dichromate, boron oxide, dichromate radical, and combinations thereof;

a second layer comprising at least one compound selected from the group consisting of cobaltous oxide, manganese sesquioxide, beryllium oxide, strontium chromate, strontium carbonate, rhodium oxide, cupric oxide, β-titanium, potassium dichromate, boron oxide, calcium dichromate, manganese dichromate, aluminum dichromate, dichromate radical, and combinations thereof; and

third layer comprising at least one compound selected from the group consisting of denatured rhodium oxide, potassium dichromate, denatured radium oxide, sodium dichromate, silver dichromate, monocrystalline silicon, beryllium oxide, strontium chromate, boron oxide, sodium peroxide, β-titanium, a metal dichromate, and combinations thereof.

13. The light emitting apparatus as set forth in claim 11 , further comprising:

a heat sink, the thermally superconducting heat transfer medium disposed between the heat sink and the printed circuit board, the thermally superconducting heat transfer medium further absorbing heat from the printed circuit board and transferring the absorbed heat to the heat sink.

14. The light emitting apparatus as set forth in claim 11 , further comprising:

a generally planar support on which the printed circuit board is mounted, the generally planar support defining the enclosed volume enclosing the thermally superconducting heat transfer medium.

15. The light emitting apparatus as set forth in claim 11 , wherein the thermally superconducting heat transfer medium is a powder-based thermally superconducting heat transfer medium.

Assignments (7)