Solid state light sheet having wide support substrate and narrow strips enclosing LED dies in series

• US 8,344,397 B2
• Filed: 05/03/2011
• Issued: 01/01/2013
• Est. Priority Date: 08/27/2010
• Status: Active Grant

• Current Assignee: Quarkstar LLC
• Original Assignee: Quarkstar LLC
• Inventors: Lerman, Louis, York, Allan Brent, Henry, Michael David, Steele, Robert, Ogonowsky, Brian D.
• Primary Examiner(s): Li, Meiya
• Application Number:
  US13/100,231
• Publication Number:
  US 20110204390A1
• Time in Patent Office: 609 Days
• Field of Search: 257 80- 82, 257/88, 257/89, 257/95, 257 98-100, 257/E33.056, 257/E33.061, 438/25, 438/28, 438/34, 438/FOR.157, 438/FOR.287, 438/FOR.46, 362/217.01, 362/249.02, 362/311.02, 362/363, 362/545, 362/555, 362611-613, 362/800, 313/483, 313498-502
• US Class Current: 257/88
• CPC Class Codes: F21K 9/20 Light sources comprising attachment means
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: F21S 8/06 by suspension
• CPC Class Codes: F21Y 2107/90 on two opposite sides of supports or substrates
• 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 2933/0033 relating to semiconductor body packages
• CPC Class Codes: H01L 2933/0066 relating to arrangements for conducting electric current to or from the semiconductor body
• CPC Class Codes: H01L 2933/0075 relating to heat extraction or cooling elements
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than 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: H01S 5/4025 Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence

Abstract

A solid state light sheet and method of fabricating the sheet are disclosed. In one embodiment, bare LED chips have top and bottom electrodes, where the bottom electrode is a large reflective electrode. The bottom electrodes of an array of LEDs (e.g., 500 LEDs) are bonded to an array of electrodes formed on a flexible bottom substrate. Conductive traces are formed on the bottom substrate connected to the electrodes. A transparent top substrate is then formed over the bottom substrate. Various ways to connect the LEDs in series are described along with many embodiments. In one method, the top substrate contains a conductor pattern that connects to LED electrodes and conductors on the bottom substrate.

Claims

1. A lighting device comprising:

a base substrate comprising a top surface and a bottom surface opposing the top surface;

a plurality of snap-in features, the snap-in features being spaced apart from one another along first and second orthogonal dimensions of the base substrate, each snap-in feature of the plurality of snap-in features comprising a first surface, a second surface opposing the first surface, and a side surface, the second surface of the snap-in feature being in contact with the top surface of the base substrate;

a plurality of cover substrates, each cover substrate of the plurality of cover substrates being elongated along the first dimension and comprising a rounded surface and a cover surface, at least a portion of the cover surface of the cover substrate being in contact with the top surface of the base substrate, and the rounded surface of the cover substrate having a rounded shape, wherein the cover surface of the cover substrate comprises a quantity of indentations, the indentations being spaced apart from one another and distributed along the first dimension, each of the indentations being shaped to conform with at least a portion of the side surface of the quantity of corresponding snap-in features, and wherein the cover substrate is disposed over the quantity of corresponding snap-in features, such that at least portions of the indentations are in contact with the at least a portion of the side surface of the quantity of corresponding snap-in features;

a plurality of non-packaged light emitting diode (LED) dies, each non-packaged LED die being encapsulated between one of the plurality of snap-in features and a respective cover substrate of the plurality of cover substrates in a corresponding indentation of the cover surface of the respective cover substrate, such that during operation of the lighting device a peak intensity of light emitted by the non-packaged LED die is output through the rounded surface of the respective cover substrate; and

a first set of conductors and a second set of conductors configured to provide power to the non-packaged LED dies, where the non-packaged LED dies are connected to the first set of conductors and the second set of conductors without wires, and the first set of conductors is formed, at least in part, on the first surface of the snap-in features and the second set of conductors is formed, at least in part, on the cover surface of the cover substrate, wherein at least a first portion of the first set of conductors are physically connected to at least a first portion of the second set of conductors.

2. The lighting device of claim 1, wherein at least a second portion of the first set of conductors and at least a second portion of the second set of conductors electrically connect with no intervening layer.

3. The lighting device of claim 1, wherein the plurality of non-packaged LED dies are vertical diodes, each diode having a first die electrode on a first surface and a second die electrode on an opposite surface, wherein at least a second portion of the first set of conductors are connected to the first die electrodes and at least a second portion of the second set of conductors are connected to the second die electrodes, such that the second portion of the first set of conductors and the second portion of the second set of conductors provide power to at least a portion of the plurality of non-packaged LED dies.

4. The lighting device of claim 1, further comprising a wavelength conversion layer in contact with at least a portion of the rounded surface of at least some of the plurality of cover substrates.

5. The lighting device of claim 4, wherein the wavelength conversion layer comprises a phosphor to create an alternative composition of light wavelengths.

6. The lighting device of claim 1, wherein LED dies of each of multiple sets of LED dies from the plurality of non-packaged LED dies are connected in series with each other, and wherein the multiple sets of LED dies are connected in parallel with each other.

7. The lighting device of claim 6, a further comprising multiple current sources, each of the multiple current sources connected in series to a respective one of the multiple sets of LED dies.

8. The lighting device of claim 1, wherein at least a portion of the rounded surface of the cover substrates is shaped to have a reflective portion that redirects light emitted by the non-packaged LED dies during operation of the lighting device to create a desired light emission pattern.

9. The lighting device of claim 1, further comprising an optical sheet disposed over and optically coupled with at least some of the cover substrates to create a desired light emission pattern.

10. The lighting device of claim 9, wherein the optical sheet comprises at least one of prisms or lenses.

11. The lighting device of claim 1, wherein a cross section of the indentations nominal to the first dimension comprises a cavity that substantially conforms to a shape of the non-packaged LED die.

12. The lighting device of claim 1, wherein each snap-in feature of the plurality of snap-in features and the base substrate are integrally formed.

13. A lighting device comprising:

a base substrate comprising a top surface and a bottom surface opposing the top surface;

a plurality of snap-in features, the snap-in features being spaces apart from one another along first and second orthogonal dimensions of the base substrate, each snap-in feature of the plurality of snap-in features comprising a first surface, a second surface opposing the first surface, and a side surface, the second surface of the snap-in feature being in contact with the top surface of the base substrate;

a plurality of cover substrates, each cover substrate of the plurality of cover substrates being elongated along the first dimension and comprising a rounded surface and a cover surface, at least a portion of the cover surface of the cover substrate being in contact with the top surface of the base substrate, and the rounded surface of the cover substrate having a rounded shape, wherein the cover surface of the cover substrate comprises a groove, the groove being elongated along the first dimension and shaped to conform with at least a portion of the side surface of a quantity of corresponding snap-in features, and wherein the cover substrate is disposed over the quantity of corresponding snap-in features, such that at least portions of the groove are in contact with the at least a portion of the side surface of the quantity of corresponding snap-in features;

a plurality of non-packaged light emitting diode (LED) dies, each non-packaged LED die being encapsulated between one of the plurality of snap-in features and a corresponding cover substrate in the groove therein, such that during operation of the lighting device a peak intensity of light emitted by the non-packaged LED die is output through the rounded surface of the corresponding cover substrate; and

a first set of conductors and a second set of conductors configured to provide power to the non-packaged LED dies, where the non-packaged LED dies are connected to the first set of conductors and the second set of conductors without wires, and the first set of conductors is formed, at least in part, on the first surface of the snap-in features and the second set of conductors is formed, at least in part, on the cover surface of the cover substrates, wherein at least a first portion of the first set of conductors are physically connected to at least a first portion of the second set of conductors.

14. The lighting device of claim 13, further comprising a wavelength conversion layer in contact with at least a portion of the rounded surface of at least some of the plurality of cover substrates.

15. The lighting device of claim 14, wherein the wavelength conversion layer comprises a phosphor to create an alternative composition of light wavelengths.

16. The lighting device of claim 13, wherein LED dies of each of multiple sets of LED dies from the plurality of non-packaged LED dies are connected in series with each other, and wherein the multiple sets of LED dies are connected in parallel with each other.

17. The lighting device of claim 16, further comprising multiple current sources, each of the multiple current sources connected in series to a respective one of the multiple sets of LED dies.

18. The lighting device of claim 13, wherein at least a portion of the rounded surface of the cover substrates is shaped to have a reflective portion that redirects light emitted by the non-packaged LED dies during operation of the lighting device to create a desired light emission pattern.

19. The lighting device of claim 13, further comprising an optical sheet disposed over and optically coupled with at least some of the cover substrates to create a desired light emission pattern.

20. The lighting device of claim 19, wherein the optical sheet comprises at least one of prisms or lenses.

21. The lighting device of claim 13, wherein a cross section of the groove nominal to the first dimension comprises a cavity that substantially conforms to a shape of the non-packaged LED die.

22. The lighting device of claim 13, wherein each snap-in feature of the plurality of snap-in features and the base substrate are integrally formed.

23. A lighting device comprising:

a base substrate comprising a top surface and a bottom surface opposing the top surface;

a plurality of snap-in features, each snap-in feature of the plurality of snap-in features being elongated along a first dimension of the base substrate and spaced apart from one another along a second dimension orthogonal to the first dimension, and each of snap-in features comprising a first surface, a second surface opposing the first surface, and a side surface, the second surface of the snap-in feature being in contact with the top surface of the base substrate;

a plurality of cover substrates corresponding to the plurality of snap-in features, each cover substrate of the plurality of cover substrates being elongated along the first dimension and comprising a rounded surface and a cover surface, at least a portion of the cover surface of the cover substrate being in contact with the top surface of the base substrate, and the rounded surface of the cover substrate having a rounded shape, wherein the cover surface of the cover substrate comprises a groove, the groove being elongated along the first dimension and shaped to conform with at least a portion of the side surface of the corresponding snap-in feature, and wherein the cover substrate is disposed over a corresponding snap-in feature, such that at least portions of the groove are in contact with the at least a portion of the side surface of the corresponding snap-in feature;

a plurality of non-packaged light emitting diode (LED) dies, where groups of the plurality of non-packaged LED dies are encapsulated between respective pairs of snap-in features and cover substrates along the corresponding grooves therein, such that during operation of the lighting device a peak intensity of light emitted by the non-packaged LED die is output through the rounded surface of the cover substrate of each of the pairs; and

a first set of conductors and a second set of conductors configured to provide power to the non-packaged LED dies, where the non-packaged LED dies are connected to the first set of conductors and the second set of conductors without wires, and the first set of conductors is formed, at least in part, on the first surface of the snap-in features and the second set of conductors is formed, at least in part, on the cover surface of the cover substrates, wherein at least a first portion of the first set of conductors are physically connected to at least a first portion of the second set of conductors.

24. The lighting device of claim 23, further comprising a wavelength conversion layer in contact with at least a portion of the rounded surface of at least some of the plurality of cover substrates.

25. The lighting device of claim 24, wherein the wavelength conversion layer comprises a phosphor to create an alternative composition of light wavelengths.

26. The lighting device of claim 23, wherein LED dies of each of multiple sets of LED dies from the plurality of non-packaged LED dies are connected in series with each other, and wherein the multiple sets of LED dies are connected in parallel with each other.

27. The lighting device of claim 26, further comprising multiple current sources, each of the multiple current sources connected in series to a respective one of the multiple sets of LED dies.

28. The lighting device of claim 23, wherein at least a portion of the rounded surface of the cover substrates is shaped to have a reflective portion that redirects light emitted by the non-packaged LED dies during operation of the lighting device to create a desired light emission pattern.

29. The lighting device of claim 23, further comprising an optical sheet disposed over and optically coupled with at least some of the cover substrates to create a desired light emission pattern.

30. The lighting device of claim 29, wherein the optical sheet comprises at least one of prisms or lenses.

31. The lighting device of claim 23, wherein a cross section of the groove nominal to the first dimension comprises a cavity that substantially conforms to a shape of the non-packaged LED die.

32. The lighting device of claim 23, wherein each snap-in feature of the plurality of snap-in features and the base substrate are integrally formed.