SOLID STATE LIGHT SOURCES BASED ON THERMALLY CONDUCTIVE LUMINESCENT ELEMENTS CONTAINING INTERCONNECTS

• US 20130099264A1
• Filed: 08/10/2012
• Published: 04/25/2013
• Est. Priority Date: 08/11/2011
• Status: Active Grant

• Current Assignee: Goldeneye, Inc.
• Original Assignee: Eduardo Deanda, Richard L. Ross, Scott Zimmerman, William R. Livesay
• Inventors: Zimmerman, Scott M., Livesay, William R., Ross, Richard L., DeAnda, Eduardo
• Granted Patent: US 8,575,641 B2
• Time in Patent Office: Days
• US Class Current: 257/89
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 27/15 including semiconductor components having potential barriers, specially adapted for light emission
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01322 Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/12042 LASER
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/501 characterised by the materials, e.g. binder
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H01L 33/64 Heat extraction or cooling elements
• CPC Class Codes: H01L 33/641 : characterized by the materials
• CPC Class Codes: H01L 33/642 : characterized by the shape
• CPC Class Codes: H01L 33/644 : in intimate contact or integrated with parts of the device other than the semiconductor body

Abstract

Solid state light sources based on LEDs mounted on or within thermally conductive luminescent elements provide both convective and radiative cooling. Low cost self-cooling solid state light sources can integrate the electrical interconnect of the LEDs and other semiconductor devices. The thermally conductive luminescent element can completely or partially eliminate the need for any additional heatsinking means by efficiently transferring and spreading out the heat generated in LED and luminescent element itself over an area sufficiently large enough such that convective and radiative means can be used to cool the device.

Claims

1. A self cooling light source comprising

a light emitting diode, and

a thermally conductive luminescent element on said light emitting diode, said thermally conductive luminescent element being a thermal spreading element for heat generated by said light emitting diode and said thermally conductive luminescent element, and said thermally conductive luminescent element being a light extraction means for light emitted by said light emitting diode.

2. The self cooling light source of claim 1 further comprising

wire bonds to prove electrical interconnects for said light emitting diode, and

a transparent/translucent bonding layer bonding said wire bonds to said thermally conductive luminescent element, said transparent/translucent bonding layer conducting heat generated by said light emitting diode and said thermally conductive luminescent element and said transparent/translucent bonding layer being a light extraction means for light emitted by said light emitting diode.

3. The self cooling light source of claim 2 wherein said transparent/translucent bonding layer is glass frit, polysiloxane, polysilazane, silicone, and other transparent/translucent adhesive materials.

4. The self cooling light source of claim 1 wherein said thermally conductive luminescent element is single crystal luminescent materials, polycrystalline luminescent materials, amorphous luminescent materials, thermally conductive transparent/translucent materials such as Sapphire, TPA, Nitrides, Spinel, cubic zirconia, quartz, and glass coated with a thermally conductive luminescent coating.

5. The self cooling light source of claim 1 further comprising

a high emissivity layer on said thermally conductive luminescent element, said high emissivity layer enhancing radiative cooling of heat generated by said light emitting diode and said thermally conductive luminescent element.

6. The self cooling light source of claim 5 wherein said high emissivity layer is glass frit, polysiloxane, polysilazanes, flame sprayed ceramics, and evaporative/CVD coatings.

7. The self cooling light source of claim 5 wherein said high emissivity layer is reflective to provide directionality to light emitted by said light emitting diode.

8. The self cooling light source of claim 5 wherein light emitted by said light emitting diode is emitted from both sides of said self cooling light source.

9. The self cooling light source of claim 1 further comprising two thermally conductive luminescent elements, said light emitting diode being partially or fully embedded in said two thermally conductive luminescent elements,

10. The self cooling light source of claim 1 further comprising two light emitting diodes, said two light emitting diodes being partially or fully embedded in said thermally conductive luminescent element.

11. The self cooling light source of claim 5 wherein in said thermally conductive luminescent element is Ce:

YAG or a polycrystalline alumina with a thermally fused layer of Mn doped Strontium Thiogallate and a layer of Eu doped Strontium Calcium Sulfide within a glass frit matrix.

12. The self cooling light source of claim 5 wherein said thermally conductive luminescent element is a translucent reflector.

13. The self cooling light source of claim 1 further comprising additional cooling means of heatpipes, metals, glass, ceramics, or plastics to conduct heat generated by said light emitting diode and said thermally conductive luminescent element and to diffuse, reflect or absorb light emitted by said light emitting diode.

14. The self cooling light source of claim 1 further comprising

electrical interconnects for said light emitting diode, said electrical interconnects formed by printing and lithographic means, and

a transparent/translucent bonding layer connecting said electrical interconnects to said thermally conductive luminescent element, said transparent/translucent bonding layer conducting heat generated by said light emitting diode and said thermally conductive luminescent element and said transparent/translucent bonding layer being a light extraction means for light emitted by said light emitting diode.

15. The self cooling light source of claim 14 wherein said electrical interconnects are a transparent/translucent dielectric layer.

16. The self cooling light source of claim 14 wherein said electrical interconnects are silver conductive inks or thick film silver inks.

17. The self cooling light source of claim 14 wherein said electrical interconnects are partially or fully covered by a transparent/translucent overcoat to environmentally isolate or electrically isolate said self cooling light source.

18. The self cooling light source of claim 14 further comprising a luminescent layer on said transparent/translucent bonding layer.

19. The self cooling light source of claim 14 further comprising multiple self cooling light sources to create uniform illumination in the far field.

20. The self cooling light source of claim 1 wherein said light emitting diode is substrate free.

21. The self cooling light source of claim 1 wherein said thermally conductive luminescent element is non-flat, hemispheric in shape, curved in shape or rectangular saw tooth in shape.

22. The self cooling light source of claim 14 further comprising silver electrical interconnects on a TCO transparent/translucent bonding layer.

23. The self cooling light source of claim 1 further comprising an outer coating covering the ends of said self cooling light source to change the far field distribution of light emitted by said light emitting diode.

24. The self cooling light source of claim 1 wherein said outer coating is a scattering element of metal, diffuse scatterer, dielectric mirror, or translucent material within a matrix.

25. The self cooling light source of claim 23 wherein said self cooling light source has the shape of a candle flame and wherein said outer coating is spectrally variable such that red wavelengths are emitted more readily near the tip of said candle flame and blue wavelengths are emitted more readily near the base of said candle flame.

26. The self cooling light source of claim 1 wherein the active region of said light emitting diode for emitting light is non-square or rectangular in shape.

27. The self cooling light source of claim 1 further comprising a bonding layer between said light emitting diode and said thermally conductive luminescent element for bonding said light emitting diode to said thermally conductive luminescent element.

28. The self cooling light source of claim 1 wherein said thermally conductive luminescent element is a wavelength conversion element for light emitted by said light emitting diode.

29. The self cooling light source of claim 28 further comprising

a red emitting light emitting diode and

a blue emitting light emitting diode, said self cooling light source emitting light of a range of wavelengths.

30. The self cooling light source of claim 28 further comprising multiple light emitting diodes emitting multiple different colors of light.

31. The self cooling light source of claim 28 further comprising

two different color emitting light emitting diodes and

a barrier between said two different color emitting light emitting diodes, said barrier thermally isolating and electrically isolating said two different color emitting light emitting diodes, said self cooling light source being a dual color light source.

32. The self cooling light source of claim 28 wherein said thermally conductive luminescent element has Ce:

YAG phosphor, said self cooling light source being a white light source.

33. The self cooling light source of claim 29 wherein self cooling light source being a white light source.

34. The self cooling light source of claim 1 wherein said thermally conductive luminescent element is a waveguide for light emitted by said light emitting diode.

35. The self cooling light source of claim 1 further comprising an optic to redirect light emitted by said light emitting diode.

36. The self cooling light source of claim 1 wherein said optic is an external moveable reflector.

37. The self cooling light source of claim 1 wherein the depth of embedding said light emitting diode in said thermally conductive luminescent element adjusts the far field distributions of light emitted by said light emitting diode.

38. A self cooling light source comprising

a light emitting diode, and

a thermally conductive wavelength conversion element on said light emitting diode, said thermally conductive wavelength conversion element being a thermal spreading element for heat generated by said light emitting diode and said thermally conductive wavelength conversion element, and said thermally conductive wavelength conversion element converting the wavelength of light emitted by said light emitting diode.

39. A self cooling solid state light source, comprising:

at least one light-emitting diode (LED) die; and

at least one thermally conductive luminescent element, wherein said luminescent element includes an electrical interconnect and functions as a wavelength converter, converting at least a portion of the light emitted by said LED die to a different wavelength range, and also functions as an optical waveguide for light emitted by said LED die, and also functions as a heat spreading element, spreading heat generated by said LED die over a greater cross-sectional area, and finally provides a high emissivity layer, for optimal coupling of emitted light from the light source.

40. A self cooling solid state light source as defined in claim 39, wherein said at least one thermally conductive luminescent element also functions as a device substrate.

41. A self cooling solid state light source as defined in claim 39, wherein said self cooling solid state light source further comprises an external interconnect.

42. A self cooling solid state light source as defined in claim 39, wherein said self cooling solid state light source further comprises an environmental enclosure for said LED die.

43. A self cooling solid state light source, comprising:

at least one light-emitting diode (LED) die; and

at least one thermally conductive luminescent element bonded to the at least one LED die;

wherein light is emitted from the LED die principally in a direction through the at least one luminescent element, and heat generated in the light source is transmitted principally in the same direction as the direction of light emission, whereby heat is dissipated from the light source by a combination of radiation, conduction and convection from the at least one luminescent element, without the need for a device heat sink.

44. A self cooling solid state light source as defined in claim 43, wherein the at least one luminescent element is bonded to the LED die by a bonding layer with high thermal conductivity.

45. A self cooling solid state light source as defined in claim 44, and further comprising a high emissivity layer formed on the at least one luminescent element.

46. A self cooling solid state light source as defined in claim 43, wherein the thermally conductive luminescent element functions as a wavelength converter, an optical waveguide, a heat spreader and a device substrate.