Light-emitting dies incorporating wavelength-conversion materials and related methods

• US 9,343,443 B2
• Filed: 01/30/2015
• Issued: 05/17/2016
• Est. Priority Date: 02/05/2014
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: Cooledge Lighting Inc.
• Inventors: Pinnington, Thomas, Amini, Alborz, Tischler, Michael A., Spiga, Gianmarco, Ip, Henry
• Primary Examiner(s): COLEMAN, WILLIAM D
• Application Number:
  US14/610,324
• Publication Number:
  US 20150221835A1
• Time in Patent Office: 473 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 21/568 Temporary substrate used as encapsulation process aid H01L21/4832 and H01L21/566 take precedence
• CPC Class Codes: H01L 2224/04105 Bonding areas formed on an encapsulation of the semiconductor or solid-state body, e.g. bonding areas on chip-scale packages
• CPC Class Codes: H01L 2224/11 Manufacturing methods
• CPC Class Codes: H01L 2224/19 Manufacturing methods of high density interconnect preforms
• CPC Class Codes: H01L 25/165 Containers
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• 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 2933/005 relating to encapsulations
• CPC Class Codes: H01L 2933/0058 relating to optical field-shaping elements
• CPC Class Codes: H01L 2933/0091 Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/54 having a particular shape
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H01L 33/62 : Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

In accordance with certain embodiments, electronic devices feature a polymeric binder, a frame defining an aperture therethrough, and a semiconductor die (e.g., a light-emitting or a light-detecting element) suspended in the binder and within the aperture of the frame.

Claims

1. A method of forming a composite frame wafer comprising (i) a frame wafer defining a plurality of apertures therethrough and (ii) a plurality of discrete semiconductor dies suspended in a cured polymeric binder within the apertures, the method comprising:

providing a frame wafer (i) having a bottom surface, (ii) having a top surface opposite the bottom surface, (iii) having a thickness spanning the top and bottom surfaces, and (iv) defining a plurality of apertures (a) each extending fully through the thickness and (b) each having a sidewall, the top surface of the frame wafer surrounding each aperture;

disposing the frame wafer over a mold substrate;

disposing the plurality of discrete semiconductor dies on the mold substrate within the apertures, each semiconductor die having at least two spaced-apart contacts adjacent the mold substrate;

coating at least a portion of the frame wafer and the plurality of semiconductor dies with a polymeric binder;

curing the polymeric binder to form the composite frame wafer; and

separating the composite frame wafer from the mold substrate,

wherein the contacts of each semiconductor die remain at least partially uncoated by the polymeric binder.

2. The method of claim 1, wherein (i) one or more of the semiconductor dies is a bare-die light-emitting element and (ii) the polymeric binder is transparent to a wavelength of light emitted by the one or more semiconductor dies.

3. The method of claim 1, further comprising separating the composite frame wafer into a plurality of discrete portions, each portion comprising (i) a portion of the frame wafer defining an aperture therethrough and (ii) disposed within the aperture, at least one semiconductor die coated with cured polymeric binder.

4. The method of claim 1, further comprising:

disposing a second substrate in contact with the composite frame wafer before the composite frame wafer is separated from the mold substrate, wherein the composite frame wafer remains attached to the second substrate when the composite frame wafer is separated from the mold substrate.

5. The method of claim 1, wherein, after separation of the composite frame wafer from the mold substrate, a portion of a bottom surface of the composite frame wafer is defined by exposed surfaces of the semiconductor dies proximate the contacts thereof.

6. The method of claim 2, wherein the frame wafer is transparent to a wavelength of light emitted by the light-emitting element.

7. The method of claim 2, wherein at least a portion of the sidewall of at least one of the apertures is reflective to a wavelength of light emitted by the light-emitting element.

8. The method of claim 2, wherein the polymeric binder contains a wavelength-conversion material for absorption of at least a portion of light emitted from the semiconductor dies and emission of converted light having a different wavelength, converted light and unconverted light emitted by the semiconductor dies combining to form mixed light.

9. The method of claim 3, wherein after separation, a volume of polymeric binder surrounding each semiconductor die is substantially equal.

10. The method of claim 4, further comprising separating the composite frame wafer from the second substrate.

11. The method of claim 6, further comprising forming a reflective layer on at least a portion of the frame wafer.

12. The method of claim 7, wherein the at least a portion of the sidewall has a reflectance greater than 80% to a wavelength of light emitted by the light-emitting element.

13. The method of claim 7, wherein the at least a portion of the sidewall is coated with a reflective coating that is reflective to a wavelength of light emitted by the light-emitting element.

14. The method of claim 8, wherein at least a portion of the sidewall of at least one of the apertures is coated with reflective coating having a reflectance greater than 80% to a wavelength of light emitted by the light-emitting element and/or the wavelength-conversion material.

15. The method of claim 8, wherein the polymeric binder comprises a plurality of discrete regions, at least one of which comprises the polymeric binder without the wavelength-conversion material.

16. The method of claim 8, wherein the mixed light comprises substantially white light.

17. The method of claim 16, wherein the substantially white light has a correlated color temperature in the range of 2000 K to 10,000 K.

18. The method of claim 16, wherein a variation in the color temperature of the substantially white light emitted when each semiconductor die is individually energized is less than four MacAdam ellipses across the composite frame wafer.

19. The method of claim 16, wherein a variation in the color temperature of the substantially white light emitted when each semiconductor die is individually energized is less than 500 K across the composite frame wafer.

20. The method of claim 16, wherein a maximum divergence of color uniformity in terms of the radially averaged Δ

u′

v′

deviation from the spatially weighted average when each semiconductor die is individually energized is less than 0.01 across the composite frame wafer.

21. The method of claim 16, wherein a divergence of color temperature of the substantially white light emitted when each semiconductor die is individually energized, varies, over an angular range of 0°

to 80°

, no more than 0.006 in terms of Δ

u′

v′

deviation from a spatially weighted averaged chromaticity across the composite frame wafer.