Reflective mounting substrates for flip-chip mounted horizontal LEDs
View Patent ↗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.
1. A light emitting device comprising:
a mounting substrate;
a spaced apart reflective anode pad and reflective cathode pad disposed on the mounting substrate and having a gap therebetween, wherein the gap comprises a first portion, a second portion and a third portion, wherein the first portion and the third portion are parallel to each other and the second portion connects the first portion and the third portion, the second portion not being parallel to the first portion and the third portion; and wherein the reflective anode pad and the reflective cathode pad make at least 76% of the total package area of the mounting substrate;
a light emitting diode die including spaced apart anode contact and cathode contact 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 reflective anode pad and the cathode contact is adjacent and conductively bonded to the reflective cathode pad; and
a lens disposed on the mounting substrate that extends from the mounting substrate to surround the light emitting diode die;
wherein the reflective anode pad and the reflective cathode pad each extends continuously on the mounting substrate from the gap to at least an edge of the lens to together 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 anode pad and the reflective cathode pad each extends continuously on the mounting substrate beyond the lens.
4. A light emitting device according to claim 3 wherein the reflective anode pad and the reflective cathode pad each extends continuously to together cover 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 anode pad and the reflective cathode pad to cover substantially all of the reflective anode pad and the reflective cathode pad 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 anode pad and the reflective cathode pad to cover substantially all of the reflective anode pad and the reflective cathode pad.
8. A light emitting device according to claim 7 wherein the phosphor layer also covers the light emitting diode die.
9. A light emitting device 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 reflective anode pad and the cathode contact is adjacent and eutectically bonded to the reflective cathode pad.
10. A light emitting device 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 reflective anode pad and the cathode contact is adjacent and flux eutectically bonded to the reflective cathode pad.
11. A light emitting device according to claim 10 wherein the flux does not extend on the mounting substrate substantially beyond the anode contact and the cathode contact.
12. A light emitting device 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 reflective anode pad and the cathode contact is adjacent and conductively bonded to the reflective cathode pad.
13. A light emitting diode die according to claim 12 wherein the fiducial comprises a feature in the reflective anode pad and/or the reflective cathode pad.
14. A light emitting device according to claim 1 wherein the reflective anode pad and the reflective cathode pad each extends continuously on the mounting substrate to together cover at least about 85 percent of the mounting substrate, excluding the gap.
15. A light emitting device according to claim 1 wherein the reflective anode pad and the reflective cathode pad comprise a same material.
16. A light emitting device according to claim 15 wherein the same material is silver.
17. A light emitting device according to claim 1 wherein the reflective anode pad and the reflective cathode pad reflect at least 90% of the angle averaged radiation that impinges on the reflective anode pad and the reflective cathode pad from the light emitting diode die.
18. A package for a light emitting device comprising:
a mounting substrate;
a spaced apart reflective anode pad and reflective cathode pad disposed on the mounting substrate and having a gap therebetween, wherein the gap comprises a first portion, a second portion and a third portion wherein the first portion and the third portion are parallel to each other and the second portion connects the first portion and the third portion, the second portion not being parallel to the first portion and the third portion; and wherein the reflective anode pad and the reflective cathode pad make at least 76% of the total package area of the mounting substrate;
the mounting substrate being configured to flip-chip mount thereon a light emitting diode die including spaced apart anode contact and cathode contact that extend along a face thereof, such that the anode contact is adjacent and conductively bonded to the reflective anode pad and the cathode contact is adjacent and conductively bonded to the reflective 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 anode pad and the reflective cathode pad each extends continuously on the mounting substrate from the gap to at least an edge of the lens to together cover substantially all of the mounting substrate that lies beneath the lens, excluding the gap.
19. A package for a light emitting device according to claim 18 further comprising a reflective filler material in the gap.
20. A package for a light emitting device according to claim 18 wherein the reflective anode pad and the reflective cathode pad each extends continuously on the mounting substrate beyond the lens.
21. A package for a light emitting device according to claim 18 wherein the reflective anode pad and the reflective cathode pad reflect at least 90% of the angle averaged radiation that impinges on the reflective anode pad and the reflective cathode pad from the light emitting diode die.
22. A package for a light emitting device according to claim 18 wherein the reflective anode pad and the reflective cathode pad comprise a same material.
23. A package for a light emitting device according to claim 22 wherein the same material is silver.