Methods and apparatus for an LED light engine

• US 7,431,477 B2
• Filed: 04/22/2005
• Issued: 10/07/2008
• Est. Priority Date: 10/01/2003
• Status: Expired due to Fees

• Current Assignee: Enertron, Inc.
• Original Assignee: Enertron, Inc.
• Inventors: Chou, Der Jeou, Kulaga, Thomas, Nelson, Daniel
• Primary Examiner(s): TSO, LAURA K
• Application Number:
  US11/112,918
• Publication Number:
  US 20060239002A1
• Time in Patent Office: 1,264 Days
• Field of Search: 362/227, 362/240, 362/247, 362/249, 362/252, 362/310, 362/311, 362/543, 362/544, 362/545, 362/800
• US Class Current: 362/240
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: F21V 7/041 with conical or pyramidal surface
• CPC Class Codes: F21Y 2105/10 comprising a two-dimensional array of point-like light-generating elements
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 33/64 Heat extraction or cooling elements
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

An LED light engine comprising a high thermal conductivity substrate (e.g., a metal-clad PCB), a plurality of light-emitting-diode (LED) semiconductor devices mechanically connected to the substrate, an outer dike fixed to the substrate and surrounding at least a portion of the LED devices, and a substantially transparent polymeric encapsulant (e.g., optical-grade silicone) disposed on the plurality of LED devices and restrained by said outer dike. In one embodiment, the light engine includes a reflector (e.g., a generally conic reflector) fixed to the substrate to form the outer dike. In another embodiment, an optical component (e.g., a lens, filter, or the like) is optically coupled to the polymeric encapsulant disposed on the LED devices.

Claims

1. A light engine, comprising:

a high thermal conductivity substrate;

a plurality of light-emitting-diode (LED) devices mechanically connected to said substrate, said LED devices electrically interconnected in a circuit having first and second terminals, said first and second terminals configured to accept an input voltage;

an outer dike fixed to said substrate and surrounding at least a portion of said LED devices; and

a substantially transparent polymeric encapsulant disposed on said plurality of LED devices and restrained by said outer dike.

2. The light engine of claim 1, wherein said LED devices are electrically configured in series.

3. The light engine of claim 1, wherein said LED devices are electrically configured in parallel.

4. The light engine of claim 1, wherein said LED devices are partitioned into sets of serial LED devices and said sets are configured in parallel.

5. The light engine of claim 1, wherein said high thermal conductivity substrate comprises a metal-clad printed circuit board.

6. The light engine of claim 1, wherein said encapsulant comprises optical-grade silicone.

7. The light engine of claim 1, wherein said encapsulant is substantially flush with a top surface of said dike, and wherein said dike is substantially transparent.

8. The light engine of claim 1, wherein said substrate is coupled to a reflector ring.

9. The light engine of claim 1, further comprising an optical component provided on said polymeric encapsulant.

10. The light engine of claim 9, wherein said optical component comprises a lens.

11. The light engine of claim 10, wherein said lens is selected from the group consisting of convex, concave, and planar.

12. The light engine of claim 9, wherein said optical component comprises a filter.

13. The light engine of claim 1, wherein said plurality of LED devices comprises ratios of individually selected LED colors selected to achieve a substantially white light with a target correlated color temperature (CCT).

14. The light engine of claim 1, wherein said plurality of LED devices comprise ratios of individually selected LED colors selected to achieve a target color.

15. A light emitting device, comprising:

a thermally conductive substrate;

a plurality of light-emitting-diode (LED) devices disposed on the thermally conductive substrate, each LED device being electrically coupled between first and second terminals and including a semiconductor die disposed over a printed circuit board (PCB) pad, each semiconductor die having a bond-pad and a color selected to achieve a target correlated color temperature for the light emitting device;

a plurality of wirebonds interconnecting the bond pads of the plurality of semiconductor die;

an encapsulant deposited over the plurality of LED devices and constrained within an outer boundary, the encapsulant enveloping the plurality of wirebonds and being sufficiently soft to withstand thermal excursions of the thermally conductive substrate without fatiguing the LED devices and first and second terminals; and

a bubble lens mounted to the encapsulant, the bubble lens having a flat side connected to the encapsulant and a plurality of convex regions, each convex region of the bubble lens corresponding to one of the plurality of semiconductor die.

16. The light emitting device of claim 15, wherein at least first and second LED devices are electrically connected in series.

17. The light emitting device of claim 15, wherein at least first and second LED devices are electrically connected in parallel.

18. The light emitting device of claim 15, wherein the thermally conductive substrate is a metal-clad printed circuit board.

19. The light emitting device of claim 15, further including a reflector ring disposed on the thermally conductive substrate.

20. The light emitting device of claim 15, wherein the LED devices are made of a semiconductor material selected from the group consisting of GaAsP, GaP, AlGaAs AlGaInP, and GaInN.

21. A light emitting device, comprising:

a thermally conductive substrate;

an electrically insulating layer disposed over the thermally conductive substrate;

a plurality of printed circuit board (PCB) pads deposited over the electrically insulating layer;

a plurality of light-emitting-diode (LED) devices disposed on the plurality of PCB pads, each LED device being electrically coupled between first and second terminals, each LED device having a color selected to achieve a target correlated color temperature for the light emitting device;

an encapsulant disposed on the plurality of LED devices, the encapsulant being sufficiently pliable to withstand thermal excursions of the thermally conductive substrate without fatiguing the LEDs and first and second terminals; and

a bubble lens mounted over the encapsulant, the bubble lens having a plurality of convex regions, each convex region of the bubble lens corresponding to one of the plurality of semiconductor die.

23. The light emitting device of claim 21, wherein the thermally conductive substrate is a metal-clad printed circuit board.

24. The light emitting device of claim 21, further including a reflector ring disposed on the thermally conductive substrate.

22. A light emitting device, comprising:

a thermally conductive substrate;

an electrically insulating layer disposed over the thermally conductive substrate;

a plurality of light-emitting-diode (LED) devices disposed on the electrically insulating layer, each LED device being electrically coupled between first and second terminals, each LED device having a color selected to achieve a target correlated color temperature for the light emitting device;

an encapsulant disposed on the plurality of LED devices; and

an outer dike surrounding at least a portion of the LED devices and restraining the encapsulant.

25. A light emitting device, comprising:

a thermally conductive substrate;

an electrically insulating layer disposed over the thermally conductive substrate;

a plurality of light-emitting-diode (LED) devices disposed on the electrically insulating layer, each LED device being electrically coupled between first and second terminals, each LED device having a color selected to achieve a target correlated color temperature for the light emitting device;

an encapsulant disposed on the plurality of LED devices; and

an optical filter disposed over the encapsulant.

26. The light emitting device of claim 25, wherein the LED devices are made of a semiconductor material selected from the group consisting of GaAsP, GaP, AlGaAs AlGaInP, and GaInN.

28. The light emitting device of claim 25, wherein at least first and second LED devices are electrically connected in series or parallel.

29. The light emitting device of claim 25, wherein the thermally conductive substrate is a metal-clad printed circuit board.

30. The light emitting device of claim 25, wherein each LED device has a color selected to achieve a target color for the light emitting device.

31. The light emitting device of claim 25, wherein each LED device has a color selected to achieve a target correlated color temperature for the light emitting device.

32. The light emitting device of claim 25, further including a reflector ring disposed on the thermally conductive substrate.

33. The light emitting device of claim 25, wherein the optical filter has a shape selected from the group consisting of convex, concave, planar, bubble, and fresnel.

27. A method of making a light emitting device, comprising:

providing a thermally conductive substrate;

disposing an electrically insulating layer over the thermally conductive substrate;

disposing a plurality of light-emitting-diode (LED) devices on the electrically insulating layer, each LED device being electrically coupled between first and second terminals;

disposing an encapsulant disposed on the plurality of LED devices; and

providing an outer dike to surround at least a portion of the LED devices and restrain the encapsulant.

34. A method of making a light emitting device, comprising:

providing a thermally conductive substrate;

disposing an electrically insulating layer over the thermally conductive substrate;

depositing a plurality of printed circuit board (PCB) pads over the electrically insulating layer;

disposing a plurality of light-emitting-diode (LED) devices on the plurality of PCB pads, each LED device being electrically coupled between first and second terminals, each LED device having a color selected to achieve a target correlated color temperature for the light emitting device; and

mounting a bubble lens over the plurality of LED devices, the bubble lens having a plurality of convex regions, each convex region of the bubble lens corresponding to one of the plurality of semiconductor die.

35. The method of claim 34, wherein the thermally conductive substrate comprises a metal-clad printed circuit board.

36. The method of claim 34, including depositing an encapsulant over the plurality of LED devices, the encapsulant comprising an optical-grade silicone.

37. The method of claim 34, wherein the LED devices are made of a semiconductor material selected from the group consisting of GaAsP, GaP, AlGaAs AlGaInP, and GaInN.