Engineered-phosphor LED packages and related methods

• US 8,659,043 B1
• Filed: 04/17/2013
• Issued: 02/25/2014
• Est. Priority Date: 02/19/2013
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: Cooledge Lighting Inc.
• Inventors: Tischler, Michael A., Ashdown, Ian
• Primary Examiner(s): Fan, Michele
• Application Number:
  US13/864,801
• Time in Patent Office: 314 Days
• Field of Search: 257/98, 257/100, 257/E33.059, 257/E33.06, 257/E33.061, 313/483, 313/498, 362/84
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/13 of an individual bump connector
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 24/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• 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 2924/07802 not being an ohmic electrical conductor
• CPC Class Codes: H01L 2924/07811 Extrinsic, i.e. with electrical conductive fillers
• CPC Class Codes: H01L 2924/12035 Zener diode
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/12042 LASER
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/508 having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin

Abstract

In accordance with certain embodiments, regions of spatially varying wavelength-conversion particle concentration are formed over light-emitting dies.

Claims

1. A light-emitting device comprising:

a bare light-emitting die having (i) a top face and a bottom face opposite the top face, at least one of the top or bottom face being configured for emission of light therefrom, and (ii) a sidewall spanning the top and bottom faces;

a binder having top and bottom surfaces, both of which are substantially parallel to the top face of the light-emitting die, the top surface of the binder having a rectangular shape, wherein (i) at least a portion of the binder extends laterally beyond the sidewall of the light-emitting die, (ii) at least a portion of the binder is disposed over the top face of the light-emitting die, and (iii) a portion of the binder extends proximate the sidewall of the light-emitting die below a plane defined by the top face of the light-emitting die; and

disposed within the binder, a plurality of wavelength-conversion particles for absorbing at least a portion of light emitted from the light-emitting die and emitting converted light having a different wavelength, wherein converted light and unconverted light emitted by the light-emitting die combine to form substantially white light, wherein a divergence of color temperature of the substantially white light emitted from the light-emitting device varies, over an angular range of 0°

to 70°

, no more than 0.01 in terms of a Δ

u′

v′

deviation from a spatially weighted averaged chromaticity and u′ and

v′

are chromaticity coordinates on a chromaticity diagram;

wherein (i) a concentration of the wavelength-conversion particles varies in a direction substantially perpendicular to the top and bottom faces without varying radially toward or away from the light-emitting die, and (ii) the concentration of the wavelength-conversion particles decreases in a direction extending from the top face of the light-emitting die to the bottom face of the die.

2. The device of claim 1, wherein a portion of the binder is substantially free of wavelength-conversion particles.

3. The device of claim 1, wherein the light-emitting die comprises a light-emitting diode die.

4. The device of claim 1, wherein the light-emitting die comprises a GaN-based semiconductor material.

5. The device of claim 4, wherein the semiconductor material comprises In.

6. The device of claim 1, wherein the light-emitting die emits blue light.

7. The device of claim 1, wherein the light-emitting die emits ultraviolet light.

8. The device of claim 1, wherein the wavelength-conversion particles comprise phosphor particles.

9. The device of claim 8, wherein the phosphor particles comprise garnet and a rare-earth element.

10. The device of claim 1, wherein the divergence of color temperature of the substantially white light emitted from the light-emitting device varies, over an angular range of 0°

to 80°

, no more than 0.01 in terms of the Δ

u′

v′

deviation from a spatially weighted averaged chromaticity.

11. The device of claim 1, wherein the divergence of color temperature of the substantially white light emitted from the light-emitting device varies, over an angular range of 10°

to 75°

, no more than 0.005 in terms of the Δ

u′

v′

deviation from a spatially weighted averaged chromaticity.

12. The device of claim 1, further comprising a substrate (i) having at least two conductive traces thereon and (ii) disposed proximate the bottom face of the light-emitting die.

13. The device of claim 12, further comprising a contact pad disposed on the light-emitting die and electrically connected to a conductive trace on the substrate.

14. The device of claim 13, wherein the contact pad is electrically connected to the conductive trace by at least one of (i) a wire bond, (ii) a solder joint, (iii) an anisotropic conductive adhesive, or (iv) a conductive adhesive.

15. The device of claim 12, wherein the substrate comprises a leadframe.

16. The device of claim 12, wherein the substrate comprises a rigid material selected from the group consisting of Si, SiC, AlN, AlON, sapphire, silicon oxide, SiAlON, SiCAlON, and alloys thereof.

17. The device of claim 12, further comprising a package in which at least a portion of the light-emitting die and at least a portion of the substrate are disposed.

18. The device of claim 17, wherein the package comprises at least one of a plastic material or a ceramic material.

19. The device of claim 12, wherein the substrate comprises a flexible material.

20. The device of claim 12, wherein the substrate comprises at least one of polyethylene naphthalate, polyethylene terephthalate, polycarbonate, polyethersulfone, polyester, polyimide, polyethylene, or paper.

21. The device of claim 12, wherein the at least two conductive traces comprise at least one of copper, aluminum, silver, gold, silver ink, or carbon.

22. The device of claim 1, wherein the binder and the light-emitting die collectively define a substantially rectangular solid shape.

23. The device of claim 1, wherein the concentration of the wavelength-conversion particles varies substantially linearly.

24. The device of claim 1, wherein the concentration of the wavelength-conversion particles varies substantially step-wise linearly.

25. The device of claim 1, wherein the binder and the light-emitting die collectively define a substantially cubic solid shape.