LED array and method for fabricating same

• US 20080170396A1
• Filed: 10/31/2007
• Published: 07/17/2008
• Est. Priority Date: 11/09/2006
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Keller, Bernd, Yuan, Thomas Cheng-Hsin
• Granted Patent: US 10,295,147 B2
• Time in Patent Office: Days
• US Class Current: 362/244
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: F21S 2/005 of modular construction
• CPC Class Codes: F21V 5/007 Array of lenses or refractors for a cluster of light sources, e.g. for arrangement of multiple light sources in one plane combination of two or more refractors F21V5/008
• CPC Class Codes: F21V 5/04 of lens shape
• CPC Class Codes: F21V 5/10 comprising photoluminescent material
• CPC Class Codes: F21Y 2105/10 comprising a two-dimensional array of point-like light-generating elements
• CPC Class Codes: F21Y 2107/40 on the sides of polyhedrons, e.g. cubes or pyramids
• CPC Class Codes: F21Y 2113/00 Combination of light sources
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• 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

Abstract

A light emitting device or array comprising a submount having a top surface, a bottom surface and a plurality of edges, with input and output terminals disposed on the top surface. A plurality of attach pads and traces are also disposed on the top surface and electrically connected between the input and output terminals. A plurality of LEDs are also included, each of which is mounted to one of the attach pads. The attach pads cover more of the top surface than the LEDs and spread heat from the LEDs to the top surface of the submount. A plurality of lenses are also included each of which is molded over a respective one of the attach pads and covers the LED mounted to the particular attach pad. The arrays are shaped and arranged so that they can be easily attached to similar arrays in a tiling fashion, with the desired number of arrays included to meet the desired lighting requirements. Methods for fabricating the arrays from a single submount or submounts panel are also disclosed.

Claims

1. An emitter array, comprising:

a submount having a plurality of edges;

input and output terminals on said submount;

a plurality of attach pads on said submount;

a plurality of solid state emitters, at least one of each mounted on and electrically connected to each of said attach pads, said attach pads covering more of said submount than said emitters and laterally spreading heat from said emitters to the surface of said submount;

a plurality of electrical connections connecting said emitters and attach pads with said input and output terminals; and

a plurality of lenses, each of which is molded over a respective one of said attach pads and each of which covers said at least one of said emitters attached to said respective one of said attach pads.

2. The array of claim 1, wherein said solid state emitters comprise light emitting diodes (LEDs).

3. The array of claim 1, wherein said attach pads extend on said surface of said submount from the edge of said emitters.

4. The array of claim 2, wherein said attach pads extend radially on said surface of said submount from the edge of said emitters.

5. The array of claim 1, wherein said substrate is polygonal.

6. The array of claim 1, wherein said submount has a top and bottom surface, said input and output terminals on the top surface or bottom surface of said submount.

7. The array of claim 1, said input terminal further comprising a first set of contact pads disposed proximate to a corresponding plurality of said edges.

8. The array of claim 7, wherein said output terminal further comprising a second set of contact pads disposed proximate to a corresponding plurality of said edges opposite said first set of contact pads.

9. The array of claim 1, wherein said electrical connections comprise wire bonds and electrical traces.

10. The array of claim 1, wherein said electrical connections connect said emitters and said attach pads in series between said input and output terminals.

11. The array of claim 1, further comprising a heat spreader disposed on said bottom surface submount.

12. The array of claim 1, further comprising secondary optics over at least some of said plurality of lenses.

13. An LED array, comprising:

a submount having a top surface, a bottom surface and a plurality of edges;

input and output terminals on said top surface;

a plurality of electrically and thermally conductive elements on said top surface;

a plurality of LEDs attached to said conductive elements, an electrical signal applied to said conductive elements causing said LEDs to emit light, at least some of said conductive elements spreading heat from said LEDs across the said submount top surface; and

a plurality of lenses, each of which is molded over a respective one of said electrical elements.

14. The array of claim 13, wherein said conductive elements comprise a plurality of attach pads and traces electrically connected between said input and output terminals, at least one of said LEDs attached to each of said attach pads, said attach pads spreading heat from said LEDs across the top surface of said submount.

15. The array of claim 14, wherein at least some of some attach pads cover more of said top surface than its at least one of said LEDs, said attach pads extending on said top surface from the edge of said LEDs.

16. The array of claim 13, wherein said submount is hexagonal.

17. The array of claim 13, further comprising secondary optics over at least some of said plurality of lenses.

18. A lamp, comprising:

a lamp body having an opening;

a light source arranged within said body to radiate light out of said body through said opening, said light source comprising at least one array, each said array comprising;

an input and an output terminal on a submount, said terminals connected to said network;

a plurality of top electrically and thermally conductive elements on a surface of said submount;

a plurality of LEDs at least one of which is attached to said top elements, power from said network causing said LEDs to emit light, said top elements spreading heat from said LEDs across the said submount top surface; and

a plurality of lenses, each of which is molded to said submount over at least one of said LEDs.

19. The lamp of claim 18, wherein said at least one array comprises a plurality of arrays arranged in an expandable tiling on a surface within said body and further comprising a network of conductors connected to provide power to said arrays.

20. The lamp of claim 19, wherein said surface is thermally conductively coupled to a heat sink.

21. The lamp of claim 18, further comprising secondary optics over at least some of said plurality of lenses.

22. A method for fabricating an emitter array, comprising:

providing a submount;

forming sets of electrically conductive features on one surface of said submount;

attaching a plurality of LEDs to said electrically conductive features such that said LEDs are electrically connected by said plurality of conductive features, said conductive features sized to spread heat from said LEDs into at least a portion of said submount;

molding a plurality of lenses on said submount with each of said lenses over one of said LEDs.

23. The method of claim 22 further comprising depositing a solder mask partially over said conductive features.

24. The method of claim 22, further comprising mounting secondary optics over said lenses.

25. A method for fabricating a plurality of arrays, comprising:

providing a submount panel sized to accommodate formation of a plurality of arrays;

forming sets of attach pads and contact pads and traces on said submount panel, with each of said sets corresponding to one of said arrays to be formed from said submount panel;

attaching a plurality of LEDs to said submount panel, at least one of said LEDs attached to one of said attach pads;

molding a plurality of lenses on said submount panel, each of said lenses over one of said LEDs; and

singulating said substrate panel to separate it into a plurality of arrays each of which comprises a plurality of LED electrically connected so that a signal applied to one of said contact pads conducted to illuminate the LEDs on the particular array.