Flexible circuit board for LED lighting fixtures

• US 10,134,714 B2
• Filed: 11/08/2013
• Issued: 11/20/2018
• Est. Priority Date: 11/08/2013
• Status: Active Grant

• Current Assignee: OSRAM GmbH (Ams-Osram AG)
• Original Assignee: OSRAM Sylvania Inc. (Ams-Osram AG)
• Inventors: Speer, Richard, Hamby, David, Selverian, John
• Primary Examiner(s): Le, Thao X
• Assistant Examiner(s): Ojeh, Nduka
• Application Number:
  US14/075,142
• Publication Number:
  US 20150129909A1
• Time in Patent Office: 1,838 Days
• Field of Search: 257 79-103, 257E33056, 257E33066, 438 22, 438 26, 438 27
• 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 2933/0016 relating to electrodes
• CPC Class Codes: H01L 2933/0033 relating to semiconductor body packages
• CPC Class Codes: H01L 2933/0058 relating to optical field-shaping elements
• CPC Class Codes: H01L 2933/0066 relating to arrangements for conducting electric current to or from the semiconductor body
• CPC Class Codes: H01L 33/60 Reflective elements
• 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: H05K 1/0274 Optical details, e.g. printed circuits comprising integral optical means H05K1/0269 takes precedence; coupling light guides with opto-electronic components G02B6/42
• CPC Class Codes: H05K 1/0287 having an universal lay-out, e.g. pad or land grid patterns or mesh patterns
• CPC Class Codes: H05K 1/181 associated with surface mounted components
• CPC Class Codes: H05K 1/189 characterised by the use of a flexible or folded printed circuit H05K3/326 takes precedence
• CPC Class Codes: H05K 2201/10106 Light emitting diode [LED]
• CPC Class Codes: H05K 2201/1028 Thin metal strips as connectors or conductors
• CPC Class Codes: H05K 2201/2054 Light-reflecting surface, e.g. conductors, substrates, coatings, dielectrics
• CPC Class Codes: H05K 2203/063 of preperforated insulating layer
• CPC Class Codes: H05K 3/103 by bonding or embedding conductive wires or strips

Abstract

Techniques are disclosed for making a flexible laminated circuit board using a metal conductor onto which a SMD may be attached. Conductive metal strips may be laminated to form a flexible substrate and the metal strips may then be perforated for the placement of LED package leads. The LED packages may be attached to the conductive strips using solder or a conductive epoxy and the upper laminate layer may include perforations exposing portions of the metal strips for the attachment of the LED packages. Alternatively, strings of LED packages may be fabricated by attaching LED packages to conductive strips and these strings may be laminated between flexible sheets to form a laminated LED circuit. Plastic housings may aid in attaching the LED packages to the conductive strips. The plastic housings and/or the laminate sheets may be made of a reflective material.

Claims

1. A flexible circuit comprising:

a perforated upper laminate sheet formed of polymeric material;

a lower laminate sheet formed of polymeric material;

a plurality of metallic conductors laminated between the perforated upper laminate sheet and the lower laminate sheet, wherein metallic contacts of the conductors are exposed by perforations in the perforated upper laminate sheet;

wherein each metallic conductor comprises at least one of a metallic ribbon, a metallic tape, and/or a metallic wire;

wherein each metallic conductor provides two metallic contacts at opposing ends thereof, and each metallic conductor extends between adjacent perforations;

wherein each metallic conductor is clampingly retained between the upper and lower laminate sheets; and

a plurality of surface mount devices attached to the metallic contacts of two adjacent metallic conductors.

2. The circuit of claim 1 wherein the plurality of surface mount devices comprise a plurality of LED packages.

3. The circuit of claim 2 wherein the plurality of LED packages are attached to the metallic conductors in at least two series strings connected in parallel.

4. The circuit of claim 3 wherein the plurality of LED packages are attached to the metallic conductors in a string formation.

5. The circuit of claim 1 wherein at least one of the perforated upper laminate sheet and/or the lower laminate sheet has a reflective surface.

6. The circuit of claim 1 wherein the plurality of surface mount devices are attached to the metallic contacts using solder or conductive epoxy.

7. A method of fabricating a flexible circuit comprising:

perforating an upper laminate sheet formed of polymeric material;

laminating a metallic conductor strip between the upper laminate sheet and a lower laminate sheet to clampingly retain the metallic conductor strip between the upper and lower laminate sheets, the lower laminate sheet being formed of polymeric material, wherein the perforations of the upper laminate sheet expose portions of the conductor strip;

perforating the exposed portions of the metallic conductor strip to form a plurality of metallic conductors, whereby each metallic conductor provides two metallic contacts at opposing ends thereof, and each metallic conductor extends between adjacent perforations in the upper laminate sheet; and

attaching a plurality of LED packages across respective said perforated portions of the metallic conductor strip at said metallic contacts.

8. The method of claim 7 wherein at least one of the perforated upper laminate sheet and/or the lower laminate sheet has a reflective surface.

9. The method of claim 7 wherein perforating the metallic conductors comprises at least one of punching a hole across the exposed conductors and/or cutting away a section of the exposed conductors.

10. The method of claim 7 wherein attaching the LED packages comprises attaching the LED packages with solder or conductive epoxy.

11. The method of claim 10 wherein the LED packages are attached with a conductive epoxy, and wherein the method further comprises curing the epoxy.

12. The method of claim 7 wherein the LED packages are attached to the metallic conductors forming at least two series strings of LED packages.

13. A method of fabricating a flexible circuit comprising:

molding a plurality of plastic housings around a metallic conductor strip, wherein a portion of the conductor is exposed within the plastic housings;

perforating the exposed portions of the metallic conductor strip to form a plurality of metallic conductors, whereby each metallic conductor provides two metallic contacts at opposing ends thereof, and each metallic conductor extends between adjacent plastic housings;

forming a string of LED packages by attaching a plurality of LED packages across respective said perforated portions of the metallic conductor strip at said metallic contacts; and

laminating the string of LED packages between a lower laminate sheet formed of polymeric material and a perforated upper laminate sheet formed of polymeric material, thereby clampingly retaining the metallic conductors between the upper and lower laminate sheets, whereby each metallic conductor extends between adjacent perforations in the upper laminate sheet and wherein perforations in the upper laminate sheet leave respective said LED packages exposed.

14. The method of claim 13 wherein perforating the metallic conductors comprises at least one of punching a hole across the exposed conductors and/or cutting away a section of the exposed conductors.

15. The method of claim 13 wherein the metallic conductors comprise at least one of a metallic ribbon, a metallic tape, and/or a metallic wire.

16. The method of claim 13 further comprising cutting the string of LED packages to a desired length prior to laminating the string of LED packages.

17. The method of claim 16 wherein the length of the LED package strings is determined by the desired DC voltage drop across the strings.

18. The method claim 13 wherein attaching the LED packages comprises attaching the LED packages to the conductive wire using solder or conductive epoxy.

19. The method of claim 13 wherein the plastic housings are molded from a reflective polymer material.