REFLECTIVE MOUNTING SUBSTRATES FOR FLIP-CHIP MOUNTED HORIZONTAL LEDS

• US 20120193662A1
• Filed: 07/08/2011
• Published: 08/02/2012
• Est. Priority Date: 01/31/2011
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Donofrio, Matthew, Edmond, John Adam, Andrews, Peter Scott, Chang, David Der Chi
• Granted Patent: US 9,673,363 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• 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

Abstract

A light emitting device includes a mounting substrate having a reflective layer that defines spaced apart anode and cathode pads, and a gap between them. A light emitting diode die is flip-chip mounted on the mounting substrate, such that the anode contact of the LED die is bonded to the anode pad and the cathode contact of the LED die is bonded to the cathode pad. A lens extends from the mounting substrate to surround the LED die. The reflective layer extends on the mounting substrate to cover substantially all of the mounting substrate that lies beneath the lens, excluding the gap, and may also extend beyond the lens.

Claims

1. A light emitting device comprising:

a mounting substrate including a reflective layer thereon that defines spaced apart anode and cathode pads and a gap therebetween;

a light emitting diode die including spaced apart anode and cathode contacts that extend along a face thereof, the light emitting diode die being flip-chip mounted on the mounting substrate such that the anode contact is adjacent and conductively bonded to the anode pad and the cathode contact is adjacent and conductively bonded to the cathode pad; and

a lens that extends from the mounting substrate to surround the light emitting diode die;

wherein the reflective layer extends on the mounting substrate to cover substantially all of the mounting substrate that lies beneath the lens, excluding the gap.

2. A light emitting device according to claim 1 further comprising a reflective filler material in the gap.

3. A light emitting device according to claim 1 wherein the reflective layer extends on the mounting substrate beyond the lens.

4. A light emitting device according to claim 3 wherein the reflective layer covers substantially all of the mounting substrate, excluding the gap.

5. A light emitting device according to claim 1 further comprising a phosphor layer that extends on the reflective layer to cover substantially all of the reflective layer that extends beyond the light emitting diode die and that lies beneath the lens.

6. A light emitting device according to claim 5 wherein the phosphor layer also covers the light emitting diode die.

7. A light emitting device according to claim 4 further comprising a phosphor layer that extends on the reflective layer to cover substantially all of the reflective layer.

8. A light emitting device according to claim 7 wherein the phosphor layer also covers the light emitting diode die.

9. A light emitting diode die according to claim 1 wherein the light emitting diode die is flip-chip mounted on the mounting substrate such that the anode contact is adjacent and eutectically bonded to the anode pad and the cathode contact is adjacent and eutectically bonded to the cathode pad.

10. A light emitting diode die according to claim 1 wherein the light emitting diode die is flip-chip mounted on the mounting substrate such that the anode contact is adjacent and flux eutectically bonded to the anode pad and the cathode contact is adjacent and flux eutectically bonded to the cathode pad.

11. A light emitting diode die according to claim 10 wherein the flux does not extend on the mounting substrate substantially beyond the anode and cathode contacts.

12. A light emitting diode die according to claim 1 wherein the mounting substrate also includes a fiducial thereon that is configured to facilitate the light emitting diode die being flip-chip mounted on the mounting substrate such that the anode contact is adjacent and conductively bonded to the anode pad and the cathode contact is adjacent and conductively bonded to the cathode pad.

13. A light emitting diode die according to claim 12 wherein the fiducial comprises a feature in the reflective layer.

14. A light emitting diode die according to claim 1 wherein the reflective layer extends on the mounting substrate to cover at least about 85 percent of the mounting substrate that lies beneath the lens, excluding the gap.

15. A light emitting device comprising:

a mounting substrate including spaced apart anode and cathode pads thereon that define a gap therebetween;

a light emitting diode die including spaced apart anode and cathode contacts that extend along a face thereof, the light emitting diode die being flip-chip mounted on the mounting substrate such that the anode contact is adjacent and conductively bonded to the anode pad and the cathode contact is adjacent and conductively bonded to the cathode pad; and

a reflective filler material in the gap.

16. A light emitting device according to claim 15 wherein the reflective filler material completely fills the gap.

17. A light emitting device according to claim 15 wherein the reflective filler material comprises white solder mask.

18. A light emitting device according to claim 15 wherein the reflective filler material comprises a low modulus material having reflective particles therein.

19. A package for a light emitting device comprising:

a mounting substrate including a reflective layer thereon that defines spaced apart anode and cathode pads and a gap therebetween;

the mounting substrate being configured to flip-chip mount thereon a light emitting diode die including spaced apart anode and cathode contacts that extend along a face thereof, such that the anode contact is adjacent and conductively bonded to the anode pad and the cathode contact is adjacent and conductively bonded to the cathode pad;

the mounting substrate being further configured to mount thereon a lens that extends from the mounting substrate to surround the light emitting diode die;

wherein the reflective layer extends on the mounting substrate to cover substantially all of the mounting substrate that lies beneath the lens, excluding the gap.

20. A package for a light emitting device according to claim 19 further comprising a reflective filler material in the gap.