Discrete phosphor chips for light-emitting devices and related methods

• US 9,478,715 B2
• Filed: 02/14/2014
• Issued: 10/25/2016
• Est. Priority Date: 01/24/2012
• Status: Active Grant

• Current Assignee: Epistar Corporation (Ennostar, Inc.)
• Original Assignee: Cooledge Lighting Inc.
• Inventors: Tischler, Michael A.
• Primary Examiner(s): Green, Tracie Y
• Application Number:
  US14/180,602
• Publication Number:
  US 20140227812A1
• Time in Patent Office: 984 Days
• Field of Search: 445 24- 25, 257/98, 257/40, 313/498, 313501-512
• US Class Current: 1/1
• CPC Class Codes: H01L 21/00 Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
• CPC Class Codes: H01L 2224/13022 the bump connector being at least partially embedded in the surface
• CPC Class Codes: H01L 2224/16145 the bodies being stacked
• CPC Class Codes: H01L 2224/73259 Bump and HDI connectors
• CPC Class Codes: H01L 24/96 the devices being encapsulated in a common layer, e.g. neo-wafer or pseudo-wafer, said common layer being separable into individual assemblies after connecting
• 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 25/00 Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereofdevices consisting of a plurality of solid state components formed in or on a common substrate H01L27/00; photovoltaic modules or arrays of photovoltaic cells H01L31/042 ; panels or arrays of photo electrochemical cells H01G9/2068
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 27/14 including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation radiation-sensitive components structurally associated with one or more electric light sources only H01L31/14; couplings of light guides with optoelectronic elements G02B6/42
• CPC Class Codes: H01L 29/00 Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor H01L31/00 - H01L33/00, H10K10/00, H10N take precedence; details other than of semiconductor bodies or of electrodes thereof H01L23/00; devices consisting of a plurality of solid state components formed in or on a common substrate H01L27/00
• 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 2924/01005 Boron [B]
• 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 2924/12032 Schottky diode
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/12042 LASER
• CPC Class Codes: H01L 2924/12043 Photo diode
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/1815 Shape
• CPC Class Codes: H01L 2933/0033 : relating to semiconductor body packages
• CPC Class Codes: H01L 2933/0041 : relating to wavelength conversion elements
• CPC Class Codes: H01L 31/0203 : Containers; Encapsulations , e.g. encapsulation of photodiodesfor photovoltaic devices H01L31/048; for organic photosensitive devices H10K30/80
• CPC Class Codes: H01L 31/022425 : for solar cells
• CPC Class Codes: H01L 31/02322 : comprising luminescent members, e.g. fluorescent sheets upon the device
• CPC Class Codes: H01L 31/02327 : the optical elements being integrated or being directly associated to the device, e.g. back reflectors optical coatings H01L31/0216
• CPC Class Codes: H01L 31/048 : Encapsulation of modules
• CPC Class Codes: H01L 31/055 : where light is absorbed and re-emitted at a different wavelength by the optical element directly associated or integrated with the PV cell, e.g. by using luminescent material, fluorescent concentrators or up-conversion arrangements
• CPC Class Codes: H01L 33/486 : adapted for surface mounting
• CPC Class Codes: H01L 33/501 : characterised by the materials, e.g. binder
• CPC Class Codes: H01L 33/505 : characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/60 : Reflective elements
• CPC Class Codes: H05B 33/02 : Details
• CPC Class Codes: H05B 33/12 : Light sources with substantially two-dimensional radiating surfaces
• CPC Class Codes: Y02E 10/52 : PV systems with concentrators

Abstract

In accordance with certain embodiments, phosphor chips are formed and subsequently attached to light-emitting elements.

Claims

1. A method for manufacture of an electronic device comprising:

providing a solid, transparent, one-piece optic having a plurality of optical elements on a first side and a plurality of depressions defined by a second side opposite the first side, wherein at least one optical element is aligned with at least one depression;

providing at least one phosphor chip, each phosphor chip (A) comprising (i) a light-conversion material present as a plurality of phosphorescent and/or fluorescent particles and (ii) a binder, comprising at least one of silicone or epoxy, wherein the phosphorescent and/or fluorescent particles are disposed within the binder, and (B) being a preformed, discrete solid piece;

after providing the at least one phosphor chip and providing the optic, inserting each phosphor chip within a different depression in the optic;

providing a substrate having a plurality of conductive traces on a surface thereof, each pair of conductive traces being separated on the substrate by a gap therebetween;

providing a plurality of light-emitting elements (LEEs) each having (i) top and bottom opposed surfaces and (ii) first and second spaced-apart contacts disposed on the bottom surface, the optic being substantially transparent to at least one of a wavelength of light emitted by the LEEs or the at least one phosphor chip;

for each LEE, (i) disposing the LEE over the substrate such that the bottom surface of the LEE extends across a gap disposed between a pair of conductive traces on the substrate and overlaps a portion of each of the conductive traces separated by the gap, (ii) electrically coupling the first contact of the LEE to one of the pair of conductive traces, and (iii) electrically coupling the second contact of the LEE to the other one of the pair of conductive traces; and

after inserting each phosphor chip within a different depression in the optic and after electrically coupling the first and second contacts of each LEE to conductive traces, mating the substrate to the optic, whereby at least one phosphor chip is positioned to receive light from at least one LEE and each optical element is positioned to receive light from at least one LEE.

2. The method of claim 1, wherein at least one optical element comprises a refractive optic or a Fresnel optic.

3. The method of claim 1, wherein, for each optical element aligned with a depression, an optical axis of the optical element is aligned with a center of the depression.

4. The method of claim 1, wherein each phosphor chip is optically coupled to an optical element on the optic.

5. The method of claim 4, further comprising providing a material having an index of refraction greater than 1.35 between at least a portion of each phosphor chip and at least a portion of the optical element to which it is optically coupled.

6. The method of claim 1, wherein each phosphor chip is optically coupled to an LEE.

7. The method of claim 6, further comprising providing a material having an index of refraction greater than 1.35 between at least a portion of each phosphor chip and at least a portion of the LEE to which it is optically coupled.

8. The method of claim 1, wherein (i) the at least one phosphor chip comprises a plurality of phosphor chips, (ii) each phosphor chip has a thickness, and (iii) a variation in the thicknesses of the phosphor chips is less than ±

5%.

9. The method of claim 1, wherein (i) the at least one phosphor chip comprises a plurality of phosphor chips, and (ii) each phosphor chip absorbs at least a portion of light emitted from the LEE from which it receives light and emits converted light having a different wavelength, converted light and unconverted light emitted by the LEE combining to form substantially white light.

10. The method of claim 9, wherein the substantially white light emitted collectively from the different LEEs and phosphor chips has a color temperature variation less than four MacAdam ellipses.

11. The method of claim 1, further comprising electrically connecting at least one LEE to circuitry for powering the at least one LEE.

12. The method of claim 1, further comprising electrically connecting at least one LEE to circuitry for controlling optical output characteristics of the at least one LEE and the phosphor chip positioned to receive light therefrom.

13. The method of claim 12, wherein the optical output characteristic comprises at least one of chromaticity, luminous flux, correlated color temperature, color point, or color rendering index.

14. The method of claim 1, wherein each optical element is positioned to receive light from only one LEE.

15. The method of claim 1, wherein the first and second contacts of each LEE are electrically coupled to conductive traces with at least one of a conductive adhesive, an anisotropic conductive adhesive, or solder.

16. The method of claim 15, wherein (i) the first and second contacts of each LEE are electrically coupled to conductive traces with an anisotropic conductive adhesive, and (ii) a portion of the anisotropic conductive adhesive is disposed in the gap between electrical traces and substantially electrically isolates the first contact from the second contact.

17. The method of claim 1, wherein each LEE comprises a bare LED die.

18. The method of claim 1, wherein the at least one phosphor chip comprises an indentation into which an LEE is at least partially disposed when the substrate is mated to the optic, the indentation being present before the LEE is at least partially disposed therewithin.

19. The method of claim 1, wherein at least a portion of the at least one phosphor chip has a curved shape.

20. The method of claim 1, wherein each phosphor chip is substantially cured before being inserted within a different depression in the optic.

21. The method of claim 1, wherein (i) at least one LEE has a top surface, a bottom surface opposite the top surface, and at least one sidewall spanning the top and bottom surfaces, (ii) the at least one phosphor chip is disposed over the top surface of the at least one LEE but does not contact any of the at least one sidewalls of the at least one LEE.

22. The method of claim 1, further comprising providing an adhesive agent between each phosphor chip and at least one LEE to bond the phosphor chip thereto, the adhesive agent being distinct from the phosphor chip.

23. The method of claim 1, further comprising securing each phosphor chip in place mechanically with a clip or a frame disposed proximate at least one LEE.

24. The method of claim 1, wherein each phosphor chip is inserted into a different depression in the optic with a pick-and-place tool.

25. The method of claim 1, wherein providing the at least one phosphor chip comprises:

disposing within a mold a phosphor comprising the binder and the light-conversion material;

curing the phosphor; and

thereafter, removing the cured phosphor from the mold to provide the at least one phosphor chip.

26. The method of claim 25, wherein the at least one phosphor chip comprises a plurality of phosphor chips, further comprising, after the cured phosphor is removed from the mold, dividing the cured phosphor into pieces, each piece being a phosphor chip.

27. The method of claim 1, further comprising disposing a transparent material between at least one LEE and the at least one phosphor chip such that, after the substrate is mated to the optic, the at least one LEE is spaced away from the at least one phosphor chip by the transparent material.

28. The method of claim 1, wherein the binder of each phosphor chip comprises therewithin one or more materials for scattering light.

29. The method of claim 28, wherein the one or more materials for scattering light comprises at least one of fumed silica or alumina.

30. The method of claim 1, wherein the plurality of phosphorescent and/or fluorescent particles comprises at least one of lutetium aluminum garnet or yttrium aluminum garnet.