Engineered-phosphor LED packages and related methods

• US 8,933,479 B2
• Filed: 03/17/2014
• Issued: 01/13/2015
• Est. Priority Date: 02/19/2013
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: Cooledge Lighting Inc.
• Inventors: Tishcler, Michael A., Ashdown, Ian
• Primary Examiner(s): Fan, Michele
• Application Number:
  US14/215,963
• Publication Number:
  US 20140231854A1
• Time in Patent Office: 302 Days
• Field of Search: 257/98, 257/100, 257/E33.059, 257/E33.06, 257/E33.061
• 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 an emission surface;

a binder disposed over at least a portion of the emission surface; 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;

(i) converted light and unconverted light emitted by the light-emitting die combine to form substantially white light,

(ii) a concentration of the wavelength-conversion particles varies in a direction substantially perpendicular to the emission surface to result in a divergence of color temperature of the substantially white light emitted from the binder that 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

(iii) u′ and

v′

are chromaticity coordinates on a chromaticity diagram.

2. The light-emitting device of claim 1, wherein (i) the bare light-emitting die comprises a top face, a bottom face opposite the top face, and a sidewall spanning the top and bottom faces, and (ii) the emission surface comprises at least a portion of the top face.

3. The light-emitting device of claim 2, wherein the binder is disposed over at least a portion of the top face and at least a portion of the sidewall.

4. The light-emitting device of claim 1, wherein (i) the bare light-emitting die comprises a top face, a bottom face opposite the top face, and a sidewall spanning the top and bottom faces, (ii) the emission surface comprises at least a portion of the bottom face, (iii) the bare-light-emitting die comprises a second emission surface, and (iv) the second emission surface comprises at least a portion of the top face.

5. The light-emitting device of claim 4, wherein the binder is disposed over at least a portion of the bottom face and at least a portion of the top face.

6. The light-emitting device of claim 1, wherein the divergence of color temperature of the substantially white light emitted from the binder 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.

7. The light-emitting device of claim 1, wherein the divergence of color temperature of the substantially white light emitted from the binder 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.

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

9. The light-emitting device of claim 1, wherein (i) the light-emitting die comprises a GaN-based semiconductor material and (ii) the wavelength-conversion particles comprise phosphor particles.

10. The light-emitting device of claim 1, wherein the concentration of the wavelength-conversion particles does not vary radially toward or away from the light-emitting die within a plane parallel to the emission surface.

11. The light-emitting device of claim 1, further comprising (i) a contact pad disposed on the light-emitting die and (ii) a substrate having at least two conductive traces thereon, the contact pad electrically connected to one of the at least two conductive traces on the substrate.

12. The light-emitting device of claim 11, 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.

13. The light-emitting device of claim 11, wherein the substrate comprises a leadframe.

14. The light-emitting device of claim 11, wherein the substrate comprises a rigid material selected from the group consisting of Si, SiC, AN, AlON, sapphire, silicon oxide, SiAlON, SiCAlON, and alloys thereof.

15. The light-emitting device of claim 11, 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, the package comprising at least one of a plastic material or a ceramic material.

16. The light-emitting device of claim 11, wherein the substrate is flexible.

17. The light-emitting device of claim 11, wherein the substrate comprises at least one of polyethylene naphthalate, polyethylene terephthalate, polycarbonate, polyethersulfone, polyester, polyimide, polyethylene, or paper.

18. The light-emitting device of claim 11, wherein the at least two conductive traces comprise at least one of copper, aluminum, silver, gold, silver ink, or carbon.

19. The light-emitting device of claim 1, wherein the binder and the light-emitting die collectively define at least one of a substantially rectangular solid shape or a substantially cubic solid shape.

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

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

22. The light-emitting device of claim 1, wherein (i) the light-emitting die comprises first and second semiconductor layers not disposed on a semiconductor substrate, (ii) the first semiconductor layer is doped with a first polarity, and (iii) the second semiconductor layer is doped with a second polarity opposite the first polarity.

23. The light-emitting device of claim 1, wherein (i) the light-emitting die comprises first and second semiconductor layers disposed over a semiconductor substrate, (ii) the first semiconductor layer is doped with a first polarity, and (iii) the second semiconductor layer is doped with a second polarity opposite the first polarity, and (iv) the substrate has a thickness between about 1 μ

m and about 25 μ

m.

24. The light-emitting device of claim 1, wherein (i) the bare light-emitting die comprises a top face, a bottom face opposite the top face, and a sidewall spanning the top and bottom faces, (ii) the emission surface comprises at least a portion of the top face, (iii) a first portion of the binder extends laterally beyond the sidewall of the light-emitting die, and (iv) a second 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.

25. The light-emitting device of claim 1, further comprising, disposed between the emission surface and the binder, a second binder substantially free of wavelength-conversion particles.

26. The light-emitting device of claim 1, wherein (i) the binder has a bottom surface proximate the light-emitting die and a top surface opposite the bottom surface, and (ii) at least a portion of the top surface of the binder is curved.

27. The light-emitting device of claim 1, wherein the binder comprises at least one of silicone or epoxy.

28. The light-emitting device of claim 1, wherein (i) the binder has (a) a bottom surface disposed over the emission surface of the light-emitting die and (b) a top surface opposite the bottom surface, and (ii) the concentration of the wavelength-conversion particles in at least a portion of the binder increases in a direction extending from the bottom surface of the binder toward the top surface of the binder.

29. The light-emitting device of claim 1, wherein (i) the bare light-emitting die comprises a top face, a bottom face opposite the top face, and a sidewall spanning the top and bottom faces, (ii) the emission surface comprises at least a portion of the top face or at least a portion of the bottom face, (iii) the face of the bare light-emitting die opposite the emission surface is not configured for emission of light therefrom, and (iv) the concentration of the wavelength-conversion particles increases in a direction extending from the face of the light-emitting die not configured for emission of light therefrom toward the emission surface of the light-emitting die.

30. The light-emitting device of claim 1, wherein the binder is free of non-phosphor scattering particles therein.