Light emitting diodes packaged for high temperature operation
View Patent ↗In accordance with the invention, an LED packaged for high temperature operation comprises a metal base including an underlying thermal connection pad and a pair of electrical connection pads, an overlying ceramic layer, and a LED die mounted overlying the metal base. The LED is thermally coupled through the metal base to the thermal connection pad, and the electrodes are electrically connected to the underlying electrical connection pads. A low thermal resistance insulating layer can electrically insulate other areas of die from the base while permitting heat passage. Heat flow can be enhanced by thermal vias to the thermal connector pad. Ceramic layers formed overlying the base can add circuitry and assist in distributing emitted light. The novel package can operate at temperatures as high as 250° C.
1. A LED device for high temperature operation comprising:
at least one packaged LED assembly comprising a metal base having a thermal connection surface, wherein the at least one packaged LED assembly further comprises:
at least one LED die having a pair of electrodes overlying and electrically insulated from the metal base, the LED die thermally coupled through the metal base to the thermal connection surface,
a layer of ceramic overlying the metal base, the layer of ceramic having at least one opening to house the at least one LED die, and
a plurality of conductive traces insulated from the metal base, the electrodes electrically connected to the conductive traces;
an apertured printed circuit (PC) board overlying the at least one packaged LED assembly, the at least one LED die aligned with an aperture of the PC board; and
a heat sink underlying the at least one packaged LED assembly, the heat sink secured in thermal contact with the thermal connection surface of the metal base of the at least one packaged LED assembly.
2. The device of claim 1 wherein the apertured PC board further comprises electrical connections to the at least one packaged LED assembly.
3. The device of claim 1 wherein the apertured PC board is secured to the heat sink to hold the at least one packaged LED assembly in thermal contact with the heat sink.
4. The device of claim 1 wherein thermal grease is disposed between the at least one packaged LED assembly and the heat sink to facilitate thermal coupling between the at least one packaged LED assembly and the heat sink.
5. The device of claim 1 wherein the at least one packaged LED assembly is surface mounted on the PC board with the at least one LED die aligned with apertures in the board.
6. The device of claim 1 wherein the at least one packaged LED assembly is connected to contacts on the PC board by solder reflow.
7. The device of claim 1 wherein the heat sink comprises aluminum.
8. The device of claim 1 wherein a plurality of packaged LED assemblies are disposed in a closely packed hexagonal array.
9. The device of claim 1 wherein a plurality of packaged LED assemblies are distributed in sectors around the circumference of a circle and in the center of the circle to emulate a concentrated light source.
10. The device of claim 1 wherein the at least one LED die comprises a plurality of LED dies disposed on the metal base in a closely packed hexagonal array.
11. The device of claim 1 wherein the at least one LED die comprises a plurality of LED dies distributed in sectors around the circumference of a circle and in the center of the circle to emulate a concentrated light source.