Systems and methods for packaging light-emitting diode devices

• US 8,115,217 B2
• Filed: 12/11/2009
• Issued: 02/14/2012
• Est. Priority Date: 12/11/2008
• Status: Expired due to Fees

• Current Assignee: illumitex, Inc.
• Original Assignee: illumitex, Inc.
• Inventors: Duong, Dung T., Winberg, Paul N., Vaz, Oscar
• Primary Examiner(s): Thai, Luan C
• Application Number:
  US12/636,280
• Publication Number:
  US 20100148193A1
• Time in Patent Office: 795 Days
• Field of Search: 257/88, 257/98, 257/E33.056, 257/E33.061, 257/E21.499, 438/28, 438/27
• US Class Current: 257/88
• 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 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body

Abstract

Embodiments disclosed herein provide packaged LED devices in which the majority of the emitted light comes out the top of each LED chip with very little side emissions. Because light only comes out from the top, phosphor deposition and color temperature control can be significantly simplified. A package LED may include a housing positioned on a supporting submount, sized and dimensioned to accommodate a single LED chip or an array of LED chips. The LED chip(s) may be attached to the submount utilizing the Gold-to-Gold Interconnect (GGI) process or solder-based approaches. In some embodiments, phosphor may be deposited on top of the LED chip(s) or sandwiched between glass plates on top of the LED chip(s). The phosphor layer may be inside or on top of the housing and be secured to the housing utilizing an adhesive. The housing may be adhered to the submount utilizing a thermal epoxy.

Claims

1. A packaged light-emitting diode (LED) device, comprising:

a housing having a cavity;

a phosphor plate on top or within the housing;

a submount attached to the housing, wherein the submount comprises metal traces, vias, or a combination thereof; and

at least one LED chip residing in the cavity of the housing between the phosphor plate and the submount and comprising a substrate and a light emitting region, wherein the substrate comprises a side wall and an exit face on top of the side wall, wherein all or substantially all rays of light emitting from the light emitting region exit the exit face with negligible or substantially negligible side emission through the side wall of the substrate, and wherein the light emitting region is connected to the metal traces of the submount inside the housing through an electrically conductive contact area.

2. The packaged LED device according to claim 1, wherein the phosphor plate comprises a glass or clear polymer plate and a phosphor layer.

3. The packaged LED device according to claim 1, wherein the phosphor plate comprises a phosphor layer sandwiched between two plates and wherein the two plates are made of glass or clear polymer capable of withstanding reflow temperatures.

4. The packaged LED device according to claim 1, wherein the at least one LED chip and the phosphor plate is separated by an air gap or a low index optical coupling material.

5. The packaged LED device according to claim 1, further comprises an array of LED chips including the at least one LED chip.

6. The packaged LED device according to claim 5, wherein the housing and the submount are configured to support the array of LED chips.

7. The packaged LED device according to claim 1, wherein the housing comprises a three-dimensional structure with a top opening, a bottom opening, and at least three sides between the top opening and the bottom opening.

8. The packaged LED device according to claim 1, wherein the housing comprises an interior wall and wherein the interior wall defines the cavity of the housing.

9. The packaged LED device according to claim 8, wherein the interior wall is tapered.

10. The packaged LED device according to claim 8, wherein the at least one LED chip and the interior wall is separated by an air gap, a low index optical coupling material, or a combination thereof.

11. The packaged LED device according to claim 8, wherein the housing comprises a top opening through which the phosphor plate is visible, a lip around the top opening of the housing, and a shoulder area on top of the interior wall, and wherein the phosphor plate rests on the shoulder area and is held in place by the lip around the top opening of the housing.

12. The packaged LED device according to claim 1, wherein the phosphor plate is attached to the housing utilizing an adhesive capable of withstanding reflow temperatures.

13. The packaged LED device according to claim 1, wherein the submount is made of a material with high thermal conductivity.

14. The packaged LED device according to claim 1, wherein the submount is made of a material selected from a group consisting of silicon, aluminum nitride, metal, flex circuit copper, aluminum, alumina ceramic, beryllium oxide ceramic, high temperature cofire ceramic, and low temperature cofire ceramic.

15. The packaged LED device according to claim 1, wherein the housing is made of a liquid crystal polymer.

16. The packaged LED device according to claim 1, wherein the electrically conductive contact area comprises a plurality of gold stud bumps.

17. The packaged LED device according to claim 1, wherein the electrically conductive contact area comprises a plurality of soldered bumps.

18. The packaged LED device according to claim 1, wherein the housing and the submount have same or substantially same footprint.

19. The packaged LED device according to claim 18, wherein the footprint is approximately 1 mm by 1 mm.

20. A method for packaging a light-emitting diode (LED), comprising:

providing a submount, wherein the submount comprises metal traces, vias, or a combination thereof;

attaching one or more LED chips to the submount, wherein each of the one or more LED chips comprises a substrate and a light emitting region, wherein the substrate comprises a side wall and an exit face on top of the side wall, wherein all or substantially all rays of light emitting from the light emitting region exit the exit face with negligible side emission through the side wall of the substrate, and wherein the light emitting region is connected to the metal traces of the submount inside the housing through an electrically conductive contact area;

placing a housing on the submount over the one or more LED chips; and

positioning a phosphor plate on top of or within the housing.

21. The method according to claim 20, further comprising applying a thermal epoxy resin to the bottom perimeter of the housing, to a portion of the top surface of the submount, or both, prior to placing the housing on the submount.

22. The method according to claim 20, wherein the phosphor plate is positioned within the housing, further comprising joining the phosphor plate and the housing prior to positioning the phosphor plate within the housing.

23. The method according to claim 20, wherein positioning the phosphor plate further comprises deforming a portion of the housing.

24. The method according to claim 20, wherein the metal traces define a pair of a cathode and an anode on a surface of the submount.

25. The method according to claim 20, further comprising utilizing a Gold-to-Gold Interconnect process or a soldering process to attach the one or more LED chips to the submount.

26. The method according to claim 20, wherein the phosphor plate is one of a plurality of phosphor plates positioned on top of the housing, further comprising manufacturing the plurality of phosphor plates by:

applying a thin coat of an epoxy onto a glass substrate;

stenciling a grid of metal or plastic material on top of the thin coat of epoxy to create a plurality of pockets;

depositing phosphor onto the thin coat of epoxy on the glass substrate, filling the plurality of pockets with a layer of phosphor having a uniform depth; and

cutting the glass substrate to produce the plurality of phosphor plates.

27. The method according to claim 26, further comprising utilizing spin coating to deposit phosphor onto the thin coat of epoxy.

28. The method according to claim 26, further comprising applying a protection layer on top of the layer of phosphor.

29. The method according to claim 28, wherein the protection layer is made of glass or clear polymer capable of withstanding reflow conditions.

30. The method according to claim 26, wherein the thin coat of epoxy is approximately 5 to 10 μ

m in depth.