Solid state light sheet or strip having cavities formed in top substrate

• US 8,338,842 B2
• Filed: 05/03/2011
• Issued: 12/25/2012
• 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:
  US13/100,247
• Publication Number:
  US 20110204391A1
• Time in Patent Office: 602 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:

at least one light strip, the light strip comprising;

a base substrate comprising a first surface and a second surface opposing the first surface, the base substrate being elongated along a longitudinal dimension of the light strip, where the longitudinal dimension of the light strip is greater than a transverse dimension of the light strip;

a cover substrate comprising a rounded surface and a cover surface, the cover substrate being elongated along the longitudinal dimension of the light strip, the cover surface of the cover substrate being in contact with the first surface of the base substrate, and the rounded surface of the cover substrate having a rounded shape, wherein the cover surface comprises a plurality of indentations, the indentations being spaced apart from one another and distributed along the longitudinal dimension of the light strip;

a plurality of non-packaged light emitting diode (LED) dies being disposed between the base substrate and the cover substrate in respective indentations of the plurality of indentations such that during operation of the lighting device a peak intensity of light emitted by the plurality of non-packaged LED dies is output through the rounded surface of the 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 on the first surface of the base substrate and the second set of conductors is formed 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 sandwiched between the base substrate and the cover substrate.

3. The lighting device of claim 1 further comprising a reflector coupled to the second surface of the base substrate for reflecting light emitted by the non-packaged LED dies towards the base substrate during operation of the lighting device.

4. The lighting device of claim 1, wherein the base substrate and cover substrate are preformed prior to sandwiching the plurality of non-packaged LED dies.

5. The lighting device of claim 1, wherein the indentations are distributed along the longitudinal dimension of the light strip in a single line.

6. The lighting device of claim 1 further comprising a wavelength conversion layer in contact with at least a portion of the rounded surface of the cover substrate.

7. The lighting device of claim 6, wherein the wavelength conversion layer comprises phosphor to create an alternative composition of light wavelengths.

8. The lighting device of claim 1, wherein the rounded surface of the cover substrate has a hemispherical shape.

9. The lighting device of claim 8, wherein a diameter of the hemispherical shape of the cover substrate is substantially equal to the transverse dimension of the light strip.

10. The lighting device of claim 1, wherein the rounded surface of the cover substrate comprises a lens.

11. The lighting device of claim 1, wherein a transverse cross section of the cover substrate is shaped as a semi-circular segment, and a chord length of the semi-circular segment is substantially equal to the transverse dimension of the light strip.

12. The lighting device of claim 1, wherein the light strip is in a range of 2-10 millimeters wide.

13. The lighting device of claim 1, wherein a length of the strip is defined by a number of the non-packaged LED dies included in the plurality of non-packaged LED dies that are connected in series and a distance between each of the non-packaged LED dies.

14. The lighting device of claim 1, wherein some of the plurality of non-packaged LED dies are connected in series by the first set of conductors and the second set of conductors.

15. The lighting device of claim 1, wherein the at least one light strip is in plurality and are connected in parallel, and wherein the lighting device forms a lighting fixture.

16. The lighting device of claim 15 further comprising a plurality of current sources connected to at least a portion of the plurality of the light strips, wherein each of the plurality of current sources is connected to a different light strip of the plurality of light strips.

17. A lighting device comprising:

a light strip, the light strip comprising;

a base substrate comprising a first surface and a second surface opposing the first surface, the base substrate being elongated along a longitudinal dimension of the light strip, where the longitudinal dimension of the light strip is greater than a transverse dimension of the light strip;

a cover substrate comprising a rounded surface and a cover surface, the cover substrate being elongated along the longitudinal dimension of the light strip, the cover surface of the cover substrate being in contact with the first surface of the base substrate, and the rounded surface of the cover substrate having a rounded shape, wherein the cover surface comprises a groove along the longitudinal dimension of the light strip;

a plurality of non-packaged light emitting diode (LED) dies being disposed spaced apart between the base substrate and the cover substrate in the groove such that during operation of the lighting device a peak intensity of light emitted by the plurality of non-packaged LED dies is output through the rounded cover surface of the 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 on the first surface of the base substrate and the second set of conductors is formed 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.

18. The lighting device of claim 17 further comprising a wavelength conversion layer in contact with at least a portion of the rounded surface of the cover substrate.

19. The lighting device of claim 17, wherein the rounded surface of the cover substrate has a hemispherical shape.

20. The lighting device of claim 19, wherein a diameter of the hemispherical shape of the cover substrate is substantially equal to the transverse dimension of the light strip.

21. The lighting device of claim 17, wherein the rounded surface of the cover substrate comprises a lens.

22. The lighting device of claim 17, wherein a transverse cross section of the cover substrate is shaped as a semi-circular segment, and a chord length of the semi-circular segment is substantially equal to the transverse dimension of the light strip.

23. The lighting device of claim 17, wherein the light strip is in a range of 2-10 millimeters wide.