Leadframe-based packages for solid state light emitting devices having heat dissipating regions in packaging

• US 8,941,134 B2
• Filed: 09/23/2011
• Issued: 01/27/2015
• Est. Priority Date: 07/13/2006
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Loh, Ban P., Medendorp, Nicholas W. Jr., Tarsa, Eric, Keller, Bernd
• Primary Examiner(s): AHMED, SELIM U
• Application Number:
  US13/242,103
• Publication Number:
  US 20120012879A1
• Time in Patent Office: 1,222 Days
• Field of Search: 257/79, 257/98, 257/99, 257/100, 257/676, 257/666, 257/796, 257/675, 257/712, 257/713, 257/717, 257/720, 257/E23.031, 257/E33.057, 257/E33.058, 257/E33.072
• US Class Current: 257/93
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/32257 the layer connector connecting to a bonding area disposed in a recess of the surface of the item
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/49113 the connectors connecting different bonding areas on the semiconductor or solid-state body to a common bonding area outside the body, e.g. converging wires
• CPC Class Codes: H01L 2224/49171 Fan-out arrangements
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 23/49861 Lead-frames fixed on or encapsulated in insulating substrates H01L23/4985, H01L23/49805 take precedence
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01068 Erbium [Er]
• CPC Class Codes: H01L 2924/01322 Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H01L 33/483 Containers
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• 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
• CPC Class Codes: H01L 33/641 : characterized by the materials
• CPC Class Codes: H01L 33/642 : characterized by the shape
• CPC Class Codes: H01L 33/647 : the elements conducting electric current to or from the semiconductor body

Abstract

A modular package for a light emitting device includes a leadframe including a first region having a top surface, a bottom surface and a first thickness and a second region having a top surface, a bottom surface and a second thickness that is less than the first thickness. The leadframe further includes an electrical lead extending laterally away from the second region, and the package further includes a thermoset package body on the leadframe and surrounding the first region. The thermoset package body may be on both the top and bottom surfaces of the second region. A leak barrier may be on the leadframe, and the package body may be on the leak barrier. Methods of forming modular packages including thermoset package bodies on leadframes are also disclosed.

Claims

1. A modular package for a light emitting device, comprising:

a leadframe including a first region having a top surface, a bottom surface and a first thickness and a second region having a top surface, a bottom surface and a second thickness that is less than the first thickness, the leadframe further including an electrical lead extending laterally away from the second region, wherein the first region comprises a reflector cup having sidewalls extending from an upper corner of the reflector cup to a base of the reflector cup, and wherein the second region extends laterally beyond a sidewall of the first region such that the second region extends beyond the sidewall on opposing sides of the first region; and

a package body on the leadframe and surrounding the first region, wherein the package body is on the top and bottom surfaces of the electrical lead and on the bottom surface of the second region.

2. The modular package of claim 1, wherein the second region comprises a recess in the leadframe, wherein the thermoset package body at least partially fills the recess.

3. The modular package of claim 1, wherein the first region comprises a mounting region, and wherein the electrical lead is isolated from the mounting region, and wherein the package body includes upper sidewalls that define an optical cavity above the mounting region.

4. The modular package of claim 3, wherein the upper sidewalls include oblique inner surfaces that define a reflector cup surrounding the mounting region, the package further comprising an encapsulant in the reflector cup.

5. The modular package of claim 1, wherein at least a portion of the package body extends through the leadframe.

6. The modular package of claim 1, wherein a third thickness between the base of the reflector cup and the bottom surface of the first region is greater than the second thickness.

7. The modular package of claim 6, wherein a width of the first region is greater than a width of the base of the reflector cup.

8. The modular package of claim 6, wherein a width of the first region is greater than or equal to a width of the reflector cup at the upper corner thereof.

9. The modular package of claim 6, further comprising a submount on the base of the reflector cup, a solid state light emitting device on the submount, and a wirebond connection from the solid state light emitting device to the electrical lead.

10. The modular package of claim 6, wherein the package body includes upper sidewalls that define an optical cavity above the reflector cup.

11. The modular package of claim 10, wherein the reflector cup comprises a first reflector cup and wherein the upper sidewalls include oblique inner surfaces that define a second reflector cup surrounding the first reflector cup.

12. The modular package of claim 11, wherein a width of a base of the second reflector cup is greater than the width of the first reflector cup at the upper corner thereof.

13. The modular package of claim 1, wherein the thermoset package body has a bottom surface that is substantially coplanar with the bottom surface of the first region.

14. The modular package of claim 1, further comprising a plurality of electrical leads, wherein the first region comprises a plurality of mounting pads that are electrically connected to respective ones of the plurality of electrical leads and that are configured to receive a light emitting device.

15. The modular package of claim 1, wherein the thermoset package body comprises a thermoset plastic.

16. The modular package of claim 1, wherein the package body comprises a thermoset.

17. The modular package of claim 1, wherein the package body includes an upper sidewall that defines an optical cavity above the first region of the leadframe, the upper sidewall having a lowermost portion that is on the electrical lead and that is spaced apart from the leadframe.

18. The modular package of claim 1, wherein the package body includes a moat in an upper surface thereof.

19. The modular package of claim 1, further comprising a lens mounted over the first region of the leadframe, wherein sidewalls of the package body extend above a bottom surface of the lens.

20. The modular package of claim 1, wherein the portion of the package body that is on the top surface of the electrical lead and the portion of the package body that is on the bottom surface of the electrical lead comprise the same material.

21. A modular package for a light emitting device, comprising:

a leadframe including a first region having a top surface, a bottom surface and a first thickness and a second region having a top surface, a bottom surface and a second thickness that is less than the first thickness, the leadframe further including an electrical lead extending laterally away from the second region, wherein the second region extends laterally beyond a sidewall of the first region such that the second region extends beyond the sidewall on opposing sides of the first region;

a package body on the leadframe and surrounding the first region, wherein the package body is on the top and bottom surfaces of the electrical lead and on the bottom surface of the second region;

an encapsulant on the top surface of the second region, wherein the encapsulant is a different material than a material of the package body, and

a lens mounted over the first region of the leadframe, wherein the encapsulant is between the lens and leadframe, and wherein sidewalls of the package body extend above a bottom surface of the lens.

22. The modular package of claim 21, wherein the package body includes an upper sidewall that defines an optical cavity above the first region of the leadframe, the upper sidewall having a lowermost portion that is on the electrical lead and that is spaced apart from the leadframe.

23. The modular package of claim 21, wherein the package body includes a moat in an upper surface thereof.

24. The modular package of claim 21, wherein the portion of the package body that is on the top surface of the electrical lead and the portion of the package body that is on the bottom surface of the electrical lead comprise the same material.

25. A modular package for a light emitting device, comprising:

a leadframe including a first region having a top surface, a bottom surface and a first thickness and a second region having a top surface, a bottom surface and a second thickness that is less than the first thickness, the leadframe further including an electrical lead extending laterally away from the second region, wherein the second region extends laterally beyond a sidewall of the first region such that the second region extends beyond the sidewall on opposing sides of the first region;

an isolation region between the second region and the electrical lead on the opposing sides of the first region to electrically isolate the second region from the electrical lead; and

a package body on the leadframe and surrounding the first region, wherein the package body is on the top and bottom surfaces of the electrical lead and on the bottom surface of the second region.

26. The modular package of claim 25, wherein the isolation region has the second thickness.

27. The modular package of claim 26, wherein the package body is on top and bottom surfaces of the isolation region.