Power surface mount light emitting die package

• US 7,264,378 B2
• Filed: 05/27/2003
• Issued: 09/04/2007
• Est. Priority Date: 09/04/2002
• Status: Expired due to Term

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Loh, Ban P.
• Primary Examiner(s): Alavi; Ali
• Application Number:
  US10/446,532
• Publication Number:
  US 20040041222A1
• Time in Patent Office: 1,561 Days
• Field of Search: 362/294, 362/800, 257/98, 257/707, 257/712, 257/100, 361/704, 313/502, 313/512
• US Class Current: 362/294
• CPC Class Codes: H01L 2224/48091 Arched
• 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 33/54 having a particular shape
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H01L 33/642 characterized by the shape
• CPC Class Codes: H05K 1/0203 Cooling of mounted components H05K1/0272 takes precedence
• CPC Class Codes: H05K 2201/10106 Light emitting diode [LED]

Abstract

A light emitting die package is disclosed. The die package includes a substrate, a reflector plate, and a lens. The substrate is made from thermally conductive but electrically insulating material. The substrate has traces for connecting an external electrical power source to a light emitting diode (LED) at a mounting pad. The reflector plate is coupled to the substrate and substantially surrounds the mounting pad. The lens is free to move relative to the reflector plate and is capable of being raised or lowered by the encapsulant that wets and adheres to it and is placed at an optimal distance from the LED chip(s). The lens can be coated with any optical system of chemical that affects the performance of the device. Heat generated by the LED during operation is drawn away from the LED by both the substrate (acting as a bottom heat sink) and the reflector plate (acting as a top heat sink). The reflector plate includes a reflective surface to direct light from the LED in a desired direction.

Claims

1. A light emitting die packages, comprising:

a substrate having traces for connecting to a light emitting diode assembly at a mounting pad,

a reflector plate coupled to the substrate and substantially surrounding the mounting pad, the reflector plate having an opening through a top horizontal surface which forms a circular sidewall that terminates at a ledge within the opening, and

a lens substantially covering the mounting pad, wherein the lens is supported by the ledge and is free to move relative to the reflector plate due to a gap between the circular sidewall and the lens.

2. The light emitting die package recited in claim 1, further comprising a light emitting diode (LED) mounted on the substrate and connected to the traces of the substrate.

3. The light emitting die package recited in claim 2, wherein the LED is encapsulated within an optically clear polymer encapsulant, and the lens sits on the encapsulant but is free to move within the reflector plate as the encapsulant expands and contracts.

4. The light emitting die package recited in claim 1, wherein the substrate is an electrically insulating material having high thermal conductivity.

5. The light emitting die package recited in claim 1, wherein the substrate is a thermally conductive material.

6. The light emitting die package recited in claim 1, further comprising an external heat sink coupled to the substrate.

7. The light emitting die package recited in claim 6, wherein the substrate has a bottom side plated with metals for coupling with the external heat sink.

8. The light emitting die package recited in claim 1, wherein at least one trace extends from the mounting pad to a side of the substrate.

9. The light emitting die package recited in claim 1, wherein the substrate includes flanges along at least one side for mechanically engaging the reflector plate.

10. The light emitting die package recited in claim 1, wherein the reflector plate substantially surrounds the mounting pad.

11. The light emitting die package recited in claim 1, wherein the reflector plate defines a reflection surface.

12. The light emitting die package recited in claim 1, wherein the reflector plate is composed of a material having high thermal conductivity.

13. The light emitting die package recited in claim 1, wherein the reflector plate includes a plurality of legs, with at least one leg mechanically engaging the substrate for increased thermal transfer.

14. The light emitting die package recited in claim 1, wherein the reflector plate is connected to an external heat sink to allow heat from the package to be dissipated.

15. The light emitting die package recited in claim 1, wherein the reflector plate includes cooling fins for heat dissipation.

16. The light emitting die package recited in claim 1, wherein the lens includes a recess adapted to receive optical chemicals.

17. The light emitting die package recited in claim 1, wherein the lens includes luminescence converting phosphors.

18. The light emitting die package recited in claim 1, wherein the lens includes a diffusant.

19. The light emitting die package recited in claim 1, wherein the lens includes a phosphor.

20. A light emitting die package, comprising:

a substrate including traces for connecting to an LED chip on the substrate,

a reflector plate on the substrate and having a circular opening exposing the LED chip, the opening partially filled with an encapsulant which encapsulates the LED chip within the package, the opening forming a circular sidewall within the reflector plate that terminates at a ledge, and

a lens supported by the ledge and which sits on the encapsulant, wherein the lens is free to move relative to the circular sidewall of the reflector plate.

21. The light emitting die package of claim 20, wherein the lens is free to move within the reflector plate as the encapsulant expands and contracts.

22. The light emitting die package of claim 20, wherein each of the substrate and reflector plate have a heat sink capability to draw away heat generated by the LED chip during package operation.

23. The light emitting die package of claim 20, wherein a gap is provided between the lens and the circular sidewall to permit lens movement within the reflector plate.

24. A light emitting die package, comprising:

a substrate supporting an LED chip thereon that is encapsulated within an encapsulant,

a reflector plate on the substrate and having a circular opening which forms a circular sidewall within the reflector plate, and

a lens which sits within the opening on the encapsulant and which is free to move relative to the circular sidewall of the reflector plate as the encapsulant expands and contracts.