Leadframe-based packages for solid state light emitting devices and methods of forming leadframe-based packages for solid state light emitting devices

• US 8,193,547 B2
• Filed: 06/06/2011
• Issued: 06/05/2012
• 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., Keller, Bernd, Medendorp, Nicholas W. Jr.
• Primary Examiner(s): Williams, A O
• Application Number:
  US13/153,930
• Publication Number:
  US 20110233579A1
• Time in Patent Office: 365 Days
• Field of Search: 257/93, 257/98, 257/E23.066, 257/99, 257/100, 257/676, 257/E33.057, 257/E33.058, 257/E33.072, 257/E33.073, 257/666, 257/79, 257/684, 257/796, 257/675, 257/712, 257/713, 257/717, 257/720, 257/E23.031
• 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 2224/49171 Fan-out arrangements
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/3011 Impedance
• 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 33/642 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 having a top surface and including a central region having a bottom surface and having a first thickness between the top surface of the leadframe and the bottom surface of the central region. The leadframe may further include an electrical lead extending away from the central region. The electrical lead has a bottom surface and has a second thickness from the top surface of the leadframe to the bottom surface of the electrical lead. The second thickness may be less than the first thickness. The package further includes a package body on the leadframe surrounding the central region and exposing the bottom surface of the central region. The package body may be at least partially provided beneath the bottom surface of the lead and adjacent the bottom surface of the central region. Methods of forming modular packages and leadframes are also disclosed.

Claims

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

a leadframe having a top surface and including a central region having a bottom surface and having a first thickness between the top surface of the leadframe and the bottom surface of the central region wherein the central region comprises a plurality of electrically isolated die mounting regions that are configured to receive respective light emitting devices, the leadframe further including a first plurality of electrical leads that are electrically isolated from the die mounting regions of the central region and that extend laterally away from a first side of the central region, each of the first electrical leads including a first region proximate the central region and having a bottom surface and a second thickness from the top surface of the leadframe to the bottom surface of the electrical lead adjacent the central region, wherein the second thickness is less than the first thickness; and

a package body on the leadframe surrounding the central region and exposing bottom surfaces of the die mounting regions;

wherein each of the first electrical leads further comprises a second region distal from the central region, the second region having the first thickness;

wherein the package body is at least partially provided beneath the bottom surface of the first region of the lead and adjacent the bottom surface of the central region; and

wherein the leadframe comprises a plurality of second electrical leads adjacent a second side of the central region opposite the first side of the central region and that are not electrically connected to die mounting regions.

2. The modular package of claim 1, wherein the package body includes upper sidewalls that define an optical cavity above the die mounting region.

3. The modular package of claim 2, wherein the upper sidewalls include oblique inner surfaces that define a reflector cup surrounding the die mounting region.

4. The modular package of claim 3, further comprising an encapsulant above the reflector cup, the encapsulant defining a lens above the reflector cup.

5. The modular package of claim 1, wherein the package body defines an optical cavity above the top surface of the leadframe, and at least a portion of the package body extends through the leadframe.

6. The modular package of claim 3, further comprising a submount on a 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 at least one of the first electrical leads.

7. The modular package of claim 1, wherein the package body has a bottom surface that is substantially coplanar with the bottom surface of the central region of the leadframe and with the second portion of the lead.

8. The modular package of claim 1, wherein the first thickness is less than 30 mils.

9. The modular package of claim 8, wherein the first thickness is about 15 mils.

10. The modular package of claim 1, wherein the first region of the leadframe is between the central region and the second region of the leadframe.

11. The modular package of claim 1, wherein the first region defines a recess in the leadframe opposite the top surface of the leadframe.

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

a leadframe having a top surface and including a central region having a bottom surface and having a first thickness between the top surface of the leadframe and the bottom surface of the central region, wherein the central region comprises a plurality of electrically isolated die mounting regions, the leadframe further including a plurality of first electrical leads that are electrically isolated from the die mounting regions of the central region and that extend laterally away from the respective die mounting regions of the central region, the first electrical leads each including a first region proximate the respective die mounting regions of the central region and having a bottom surface and a second thickness from the top surface of the leadframe to the bottom surface of the electrical lead adjacent the central region, wherein the second thickness is less than the first thickness; and

a package body on the leadframe surrounding the central region and exposing the bottom surface of the central region;

wherein each of the first electrical leads further comprises a second region distal from the central region, the second region having the first thickness;

wherein the package body is at least partially provided beneath the bottom surface of the first region of the first electrical leads and adjacent the bottom surface of the central region;

wherein the first electrical leads extend from a first side of the modular package;

wherein the package includes a second side opposite the first side; and

wherein the leadframe comprises a plurality of second electrical leads that are not electrically connected to die mounting regions and that extend from the second side of the package.

13. The modular package of claim 12, further comprising an LED chip mounted to one of the die mounting regions that provides electrical connection between the LED chip and one of the first electrical leads.

14. The modular package of claim 13, further comprising:

an encapsulant material on the leadframe in an optical cavity defined by the package body; and

a lens on the package body.

15. A leadframe for a package for a light emitting device, comprising:

a top surface;

a central region having a bottom surface and having a first thickness between the top surface of the leadframe and the bottom surface of the central region wherein the central region comprises a plurality of electrically isolated die mounting regions; and

a first plurality of electrical leads that are electrically isolated from the die mounting regions of the central region and that extend laterally away from a first side of the central region and are electrically connected to the die mounting regions, each of the first plurality of electrical leads comprising;

a first region proximate the respective die mounting regions of the central region and having a bottom surface and a second thickness from the top surface of the leadframe to the bottom surface of the electrical lead adjacent the central region, wherein the second thickness is less than the first thickness; and

a second region distal from the central region, the second region having the second thickness;

wherein the central region includes a second side opposite the first side; and

wherein the leadframe comprises a plurality of second electrical leads adjacent the second side of the central region and that are not electrically connected to die mounting regions.

16. The leadframe of claim 15, further comprising a plurality of LED chips mounted to respective ones of the die mounting regions, wherein each of the die mounting regions provides electrical connection between a respective one of the LED chips and a respective one of the first electrical leads.