Composite leadframe LED package and method of making the same

• US 20040126913A1
• Filed: 11/25/2003
• Published: 07/01/2004
• Est. Priority Date: 12/06/2002
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Loh, Ban P.
• Granted Patent: US 7,692,206 B2
• Time in Patent Office: Days
• US Class Current: 438/26
• 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; and

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

2. The light emitting die package recited in claim 1 wherein said top heatsink is electrically separated from said leadframe.

3. The light emitting die package recited in claim 1 wherein said top heatsink and said bottom heatsink have similar lateral extents and substantially overlap each other.

4. The light emitting die package recited in claim 1 wherein said bottom heatsink has a top surface thermally coupled to but is electrically separated from said leadframe, and said bottom heatsink has a metalized bottom surface defining a bottom plane for the light emitting die package.

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

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

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

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

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

10. 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 bottom heatsink thermally coupled to the bottom side of said leadframe under the mounting pad, said bottom heatsink electrically insulated from said leadframe;

a 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, and said top heatsink coupled to a reflector also surround the mounting pad;

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.

11. The light emitting die package recited in claim 10 wherein said bottom heatsink has a metalized bottom surface defining a bottom plane for the light emitting die package.

12. The light emitting die package recited in claim 11 wherein the leads are bent toward the bottom plane, and the leads terminate proximal to the bottom plane.

13. The light emitting die package recited in claim 10 wherein the enclosed cavity is at least partially filled with encapsulant.

14. A method of manufacturing a light emitting die package, the method comprising:

fabricating a leadframe die, the leadframe die including a plurality of leads and die frame, each lead and the die frame having a top side and a bottom side;

coupling a top heatsink over the leadframe die, the top heatsink defining an opening;

coupling a bottom heatsink under the leadframe die; and

stamping the leadframe die to cut-away the die frame.

15. The method recited in claim 14 wherein the leadframe die is fabricated by stamping a sheet of die material.

16. The method recited in claim 14 wherein the leadframe die is fabricated by etching process.

17. The method recited in claim 14 further comprising mounting at least one light emitting device (LED) on at least one lead, the LED mounted in the opening.

18. The method recited in claim 14 further comprising attaching a lens on the top heatsink, the lens covering the opening.

19. The method recited in claim 14 wherein the top heatsink and the bottom heatsink have similar lateral extents and substantially overlap each other.

20. The method recited in claim 14 wherein the bottom heatsink has a top surface thermally coupled to but is electrically separated from the leadframe die, and the bottom heatsink has a metalized bottom surface defining a bottom plane for the light emitting die package.

21. The method recited in claim 20 further comprising bending the leads toward the bottom plane.

22. The method recited in claim 14 further comprising coupling a reflector on the top heatsink, said reflector surrounding the opening.

23. The method recited in claim 14 wherein the top heatsink includes an integrated reflector.