Sealed light emitting diode assemblies including annular gaskets and methods of making same

• US 20080220549A1
• Filed: 03/08/2007
• Published: 09/11/2008
• Est. Priority Date: 03/08/2007
• Status: Active Grant

• Current Assignee: Lumination LLC
• Original Assignee: Lumination LLC
• Inventors: Nall, Jeffrey, Saha, Babi Koushik, Wang, Bill Xin
• Granted Patent: US 7,633,055 B2
• Time in Patent Office: Days
• US Class Current: 438/26
• 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: F21V 31/005 Sealing arrangements therefor
• CPC Class Codes: F21V 31/04 Provision of filling media
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H05K 2201/0989 Coating free areas, e.g. areas other than pads or lands free of solder resist
• CPC Class Codes: H05K 2201/10106 Light emitting diode [LED]
• CPC Class Codes: H05K 2201/2018 Presence of a frame in a printed circuit or printed circuit assembly
• CPC Class Codes: H05K 2203/1316 Moulded encapsulation of mounted components
• CPC Class Codes: H05K 3/284 for encapsulating mounted components H05K1/185 takes precedence

Abstract

An optoelectronic device assembly includes a circuit board and an optoelectronic device disposed on the circuit board and electrically connected with the circuit board. An annular gasket is disposed on the circuit board and surrounds the optoelectronic device. A sealant is disposed over and seals at least a portion of the circuit board and also covers at least an outer annular portion of the annular gasket. The sealant is not disposed over the optoelectronic device. In a method, an optoelectronic device is disposed on a circuit board, the disposing including electrically connecting the optoelectronic device with the circuit board. An annular gasket is disposed on the circuit board to surround the optoelectronic device. The circuit board is sealed with a sealant that also covers at least an outer annular portion of the annular gasket, but does not cover the optoelectronic device.

Claims

1. A method comprising:

disposing an optoelectronic device on a circuit board, the disposing including electrically connecting the optoelectronic device with the circuit board;

disposing an annular gasket on the circuit board to surround the optoelectronic device; and

sealing the circuit board with a sealant that also covers at least an outer annular portion of the annular gasket, but does not cover the optoelectronic device.

2. The method as set forth in claim 1, wherein the sealing comprises:

overmolding the circuit board and at least an outer annular portion of the annular gasket, but not the optoelectronic device.

3. The method as set forth in claim 1, wherein the sealing comprises:

single shot overmolding the circuit board and at least an outer annular portion of the annular gasket, but not the optoelectronic device.

4. The method as set forth in claim 1, wherein the sealing comprises:

potting the circuit board and at least an outer annular portion of the annular gasket, but not the optoelectronic device.

5. The method as set forth in claim 1, wherein the sealing comprises:

performing a single step overmolding or potting process that seals the circuit board and at least an outer annular portion of the annular gasket, but not the optoelectronic device.

6. The method as set forth in claim 1, wherein the optoelectronic device and the annular gasket are disposed on a front side of the circuit board, and the sealing comprises:

sealing the front side of the circuit board but not a back side of the circuit board.

7. The method as set forth in claim 1, wherein the disposing of an annular gasket on the circuit board comprises:

adhering the annular gasket to the circuit board using an adhesive disposed between the annular gasket and the circuit board.

10. The method as set forth in claim 1, wherein the optoelectronic device includes a light emitting diode package, the method further comprising:

after the sealing, electrically energizing the light emitting diode package via the circuit board to generate light, the at least outer annular portion of the annular gasket remaining covered by the sealant during the electrical energizing.

11. The method as set forth in claim 1, further comprising:

disposing a pad or fold-over pad on or around an edge of the circuit board, wherein the sealing includes contacting the pad or fold-over pad with a pin that defines an additional opening in the sealant, the sealant covering at least a portion of the pad or fold-over pad.

30. The method as set forth in claim 1, wherein the optoelectronic device and the annular gasket are disposed on a front side of the circuit board, and the sealing comprises:

sealing both the front side of the circuit board and a back side of the circuit board.

8. A method comprising:

disposing an optoelectronic device on a circuit board, the disposing including electrically connecting the optoelectronic device with the circuit board;

disposing an annular gasket on the circuit board to surround the optoelectronic device; and

sealing the circuit board with a sealant that also covers at least an outer annular portion of the annular gasket, but does not cover the optoelectronic device, the sealing comprising (i) disposing the circuit board in an injection mold that includes a generally hollow member receiving the optoelectronic device and having an edge sealing against the gasket and (ii) injecting sealant material into the injection mold, the injected sealant material being blocked by the generally hollow member and the annular gasket from reaching the optoelectronic device.

9. The method as set forth in claim 8, further comprising:

after the injected sealant material solidifies to define the sealant, removing the circuit board from the injection mold; and

substantially filling an opening in the sealant defined by the generally hollow member with a transmissive encapsulant that is transmissive for radiation generated or received by the optoelectronic device.

12. An optoelectronic device assembly comprising:

a circuit board;

an optoelectronic device disposed on the circuit board and electrically connected with the circuit board;

an annular gasket disposed on the circuit board and surrounding the optoelectronic device; and

a sealant disposed over and sealing at least a portion of the circuit board and also covering at least an outer annular portion of the annular gasket, the sealant not being disposed over the optoelectronic device.

13. The optoelectronic device assembly as set forth in claim 12, wherein the optoelectronic device includes a light emitting diode package.

14. The optoelectronic device assembly as set forth in claim 12, wherein a gap exists between an edge of the optoelectronic device and the sealant.

15. The optoelectronic device assembly as set forth in claim 12, wherein the sealant does not contact the optoelectronic device.

16. The optoelectronic device assembly as set forth in claim 12, wherein the sealant forms a seal with an outer annular region of the annular gasket but does not contact an inner annular region of the annular gasket.

17. The optoelectronic device assembly as set forth in claim 12, wherein the sealant is substantially opaque respective to radiation generated or received by the optoelectronic device, the optoelectronic device assembly further comprising:

a transmissive encapsulant disposed over at least the optoelectronic device and the inner annular region of the annular gasket, the transmissive encapsulant being transmissive for radiation generated or received by the optoelectronic device.

18. The optoelectronic device assembly as set forth in claim 12, wherein the annular gasket is of one piece with the sealant.

19. The optoelectronic device assembly as set forth in claim 12, wherein the sealant has a conformal interface with the circuit board and at least an outer annular region of the annular gasket.

20. The optoelectronic device assembly as set forth in claim 12, wherein the annular gasket is made of the same material as the sealant.

21. The optoelectronic device assembly as set forth in claim 12, wherein the sealant is an injection overmolding.

22. The optoelectronic device assembly as set forth in claim 12, wherein the sealant is a single shot injection overmolding.

23. The optoelectronic device assembly as set forth in claim 12, wherein the sealant is a potting or hot melt.

24. The optoelectronic device assembly as set forth in claim 12, wherein the circuit board has a front side on which the optoelectronic device is disposed and a backside, and the sealant is disposed over and seals the front side of the circuit board but not the backside.

25. The optoelectronic device assembly as set forth in claim 12, further comprising;

an adhesive disposed between the annular gasket and the circuit board, the adhesive defining a seal between the annular gasket and the circuit board.

26. The optoelectronic device assembly as set forth in claim 12, wherein the annular gasket has an inner perimeter that is substantially conformal with an outer perimeter of the optoelectronic device.

27. The optoelectronic device assembly as set forth in claim 12, wherein the optoelectronic device and the annular gasket comprise a plurality of optoelectronic devices each disposed on the circuit board and each surrounded by a corresponding annular gasket disposed on the circuit board, the sealant being disposed over the circuit board and forming a seal with each annular gasket, the sealant not being disposed over any of the optoelectronic devices.

28. The optoelectronic device assembly as set forth in claim 12, further comprising:

a pad or fold-over pad disposed on or over an edge of the circuit board and sealing an opening in the sealant aligned with the pad or fold-over pad.

29. The optoelectronic device assembly as set forth in claim 12, wherein the annular gasket disposed on the circuit board and surrounding the optoelectronic device has a hardness as measured in durometer of 40 Shore A hardness or higher.

31. The optoelectronic device assembly as set forth in claim 12, wherein the circuit board has a front side on which the optoelectronic device is disposed and a backside, and the sealant is disposed over and seals both the front side of the circuit board and the backside.