Solid state lighting device

• US 7,397,068 B2
• Filed: 12/09/2004
• Issued: 07/08/2008
• Est. Priority Date: 12/23/2003
• Status: Active Grant

• Current Assignee: Tessera, Inc. (Adeia Inc.)
• Original Assignee: Tessera, Inc. (Adeia Inc.)
• Inventors: Kang, Teck-Gyu, Park, Jae M.
• Primary Examiner(s): LOUIE, WAI SING
• Application Number:
  US11/010,077
• Publication Number:
  US 20050133800A1
• Time in Patent Office: 1,307 Days
• Field of Search: 257/79, 257/39, 257/100, 257/103, 257/E25.021, 257/E33.061, 257 88- 89, 345 39- 40, 313/503
• US Class Current: 257/88
• CPC Class Codes: F21L 4/027 the light sources being a LED
• CPC Class Codes: F21L 4/085 Pocket lamps
• CPC Class Codes: F21S 9/02 the power supply being a battery or accumulator
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 25/0756 Stacked arrangements of devices
• 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 2924/3011 Impedance

Abstract

A light assembly for use with a low voltage power source. The light assembly semiconductor photo-emitters are electrically in series with a higher forward voltage drop than the associated low voltage power supply. To provide the necessary voltage the light assembly includes a current regulated step-up DC/DC converter. The semiconductor photo-emitters that are electrically in series are in the form of a monolithic light emitting diode array with a plurality of light emitting diode elements electrically and mechanically in series with a conductive, rigid bond region between the cathode region of the first light emitting diode element and the anode region of the second light emitting diode element. The first and second light emitting diode elements may differ in band gaps to emit different colors, that are additive to a non-primary color, such as white.

Claims

1. A monolithic light emitting diode series array, comprising:

a first light emitting diode element having an anode region and a cathode region;

a second light emitting diode element having an anode region and a cathode region;

a conductive, rigid bond region located between the cathode region of the first light emitting diode element and the anode region of the second light emitting diode element to connect the first and second light emitting diode elements electrically and mechanically in series;

a positive external lead on the cathode region of the first light emitting diode element;

a negative external lead on the anode region of the second light emitting element;

a package having a recess formed therein and having first and second contact pads, the connected first and second light emitting diode elements being located in the recess of the package such that one of the external leads is disposed between a surface of the connected first and second light emitting diode elements and a bottom surface of the recess and another of the leads is disposed on an opposing surface of the connected first and second light emitting diode elements;

a first wire lead connected between one of the external leads and one of the contact pads; and

a second wire lead connected between another of the external leads and another of the contact pads.

2. The monolithic light emitting diode array of claim 1 wherein the first and second light emitting diode elements differ in band gaps to thereby emit light of different colors.

3. The monolithic light emitting diode array of claim 2 wherein the light of different colors are optically additive to generate white light.

4. The monolithic light emitting diode array of claim 1 wherein the array is a linear array.

5. The monolithic light emitting diode array of claim 1 wherein the conductive, rigid bond region is a solder alloy.

6. The monolithic light emitting diode array of claim 5 wherein the solder alloy is a eutectic alloy.

7. The monolithic light emitting diode array of claim 6 wherein the eutectic alloy is a gold-tin eutectic alloy.

8. The monolithic light emitting diode array of claim 5 wherein the solder alloy includes a gold-tin alloy layer formed on a surface of one light emitting diode element and a gold pad formed on a facing surface of another light emitting diode element, the gold-tin alloy layer and gold pad together forming a conductive bond.

9. The monolithic light emitting diode array of claim 1 wherein the conductive, rigid bond region is a conductive polymer.

10. The monolithic light emitting diode array of claim 1 wherein the conductive, rigid bond region is a metallically conductive semiconductor alloy.

11. The monolithic light emitting diode array of claim 1 further comprising a third light emitting diode between the first and second light emitting diodes, electrically and mechanically in series therewith and bonded thereto.

12. The monolithic light emitting diode array of claim 11 wherein light emitting diode elements emit light of different primary colors that are optically additive to generate light of a non-primary color.

13. The monolithic light emitting diode array of claim 12, wherein the nonprimary color is white.

14. The monolithic light emitting diode array of claim 1 wherein at least one of the light emitting diode elements comprises doped Gain.

15. The monolithic light emitting diode array of claim 14 wherein the at least one light emitting diode element further comprises regions of p-GaP, AlInGaP, n-AlInGaP, and an n-GaAs substrate.