Composite leadframe LED package and method of making the same

• US 7,692,206 B2
• Filed: 11/25/2003
• Issued: 04/06/2010
• Est. Priority Date: 12/06/2002
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Loh, Ban P.
• Primary Examiner(s): Ha; Nathan W
• Application Number:
  US10/721,654
• Publication Number:
  US 20040126913A1
• Time in Patent Office: 2,324 Days
• Field of Search: 257/707, 257/666, 257 82-100, 257/678, 257/680, 257431-433, 257/E33.066, 438/51
• US Class Current: 257/99
• 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 25/0753 the devices being arranged next to each other
• 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 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 33/64 Heat extraction or cooling elements

Abstract

Light emitting die package is disclosed. The die package includes a leadframe, a bottom heatsink, a top heatsink, a reflector and a lens. The top and bottom heatsinks are thermally coupled but electrically insulated from the leadframe. The leadframe includes a plurality of leads and defines a mounting pad for mounting LEDS. The top heatsink defines an opening over the mounting pad. The reflector is coupled to the top heatsink at the opening. The lens is placed over the opening defining an enclosed cavity over the mounting pad. At least one light emitting device (LED) is mounted on the mounting pad within the cavity. Encapsulant optically couples the LED to its surrounding surfaces to maximize its optical performance. When energized, the LED generates light and heat. The light is reflected by the reflector and operated on by the lens. The heat is dissipated by the top and the bottom heatsinks.

Claims

1. A light emitting die package comprising:

a leadframe including a plurality of leads, said leadframe having top side and bottom side, and a portion of said leadframe defining a mounting pad;

a bottom heatsink coupled to the bottom side of said leadframe, said bottom heatsink having a top surface thermally coupled to but electrically separated from said leadframe;

a top heatsink coupled to the top side of said leadframe, said top heatsink defining an opening, the opening generally surrounding the mounting pad; and

at least one dielectric layer positioned between said leadframe and at least one of the top heatsink and the bottom heatsink;

wherein said top heatsink and said bottom heatsink have similar lateral dimensions, and said leadframe has lateral dimensions that are at least as great as lateral dimensions of said top heatsink and said bottom heatsink both widthwise and lengthwise.

2. The light emitting die package recited in claim 1 wherein said top heatsink is electrically separated from said leadframe by a dielectric layer positioned between said leadframe and said top heatsink.

3. The light emitting die package recited in claim 1 wherein said bottom heatsink has a metalized bottom surface defining a bottom plane for the light emitting die package.

4. The light emitting die package recited in claim 3 wherein the leads are bent toward the bottom plane, and the leads terminate proximal to the bottom plane.

5. The light emitting die package recited in claim 1 further comprising at least one light emitting device (LED) mounted on the mounting pad.

6. The light emitting die package recited in claim 1 further comprising a reflector coupled to said top heatsink, said reflector surrounding the mounting pad.

7. The light emitting die package recited in claim 1 further comprising a lens coupled to said top heatsink over the mounting pad.

8. The light emitting die package recited in claim 7 wherein an enclosed cavity is defined by the opening and said lens.

9. The light emitting die package recited in claim 1 wherein said bottom heatsink comprises a thermally conductive material.

10. The light emitting die package recited in claim 2 wherein said top heatsink comprises a thermally conductive material.

11. A light emitting die package comprising:

a leadframe including a plurality of leads, said leadframe having top side and a bottom side, and a portion of said leadframe defining a mounting pad;

a thermally conductive bottom heatsink thermally coupled to the bottom side of said leadframe under the mounting pad, said bottom heatsink electrically insulated from said leadframe by a dielectric layer positioned between said leadframe and said bottom heatsink;

a thermally conductive top heatsink thermally coupled to the top side of said leadframe, said top heatsink defining an opening, the opening generally surrounding the mounting pad, said top heatsink electrically insulated from said leadframe by a dielectric layer positioned between said leadframe and said top heatsink, and said top heatsink coupled to a reflector also surround the mounting pad;

at least one dielectric layer positioned between said leadframe and at least one of the top heatsink and the bottom heatsink;

at least one light emitting device (LED) mounted on the mounting pad, the LED adapted to generate light when energized; and

a lens coupled to said top heatsink over the opening, said lens adapted to operate on the light generated by the LED, the lens, covering the opening thereby defining an enclosed cavity;

wherein said top heatsink and said bottom heatsink have similar lateral dimensions, and said leadframe has lateral dimensions that are at least as great as the lateral dimensions of said top heatsink and said bottom heatsink both widthwise and lengthwise.

12. The light emitting die package recited in claim 11 wherein said bottom heatsink has a metalized bottom surface defining a bottom plane for the light emitting die package.

13. The light emitting die package recited in claim 12 wherein the leads are bent toward the bottom plane, and the leads terminate proximal to the bottom plane.

14. The light emitting die package recited in claim 11 wherein the enclosed cavity is at least partially filled with encapsulant.

15. A light emitting device comprising:

a leadframe having top side and bottom side, a portion of said leadframe defining a mounting pad;

a bottom heatsink coupled to the bottom side of said leadframe, said bottom heatsink having a top surface thermally coupled to but electrically separated from said leadframe; and

a top heatsink thermally coupled to the top side of said leadframe

wherein at least one of said top heatsink and said bottom heatsink is made with copper or aluminum.

16. The device of claim 15 further comprising a lens covering said mounting pad.

17. The device of claim 15 wherein said top heat sink further comprises an opening generally surrounding the mounting pad.

18. A light emitting device comprising:

a leadframe comprising a top side and bottom side;

a bottom heatsink coupled to the bottom side of said leadframe, said bottom heatsink having a top surface thermally coupled to but electrically separated from said leadframe;

a top heatsink coupled to the top side of said leadframe; and

at least one dielectric layer positioned between said leadframe and at least one of the top heatsink and the bottom heatsink;

wherein at least one of said top heatsink and said bottom heatsink is made with copper or aluminum.

19. The device of claim 18 further comprising a mounting pad on said leadframe and a lens covering said mounting pad.

20. The device of claim 18 wherein said top heat sink further comprises an opening generally surrounding the mounting pad.