Submounts for Semiconductor Light Emitting Devices and Methods of Forming Packaged Light Emitting Devices Including Dispensed Encapsulants

• US 20120061702A1
• Filed: 05/31/2011
• Published: 03/15/2012
• Est. Priority Date: 08/04/2005
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Andrews, Peter S., Loh, Ban P., Medendorp, Nicholas W. Jr., Keller, Bernd P.
• Granted Patent: US 8,835,952 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48235 connecting the wire to a via metallisation of the item
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2933/005 relating to encapsulations
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/54 having a particular shape

Abstract

A submount for mounting an LED chip includes a substrate, a die attach pad configured to receive an LED chip on an upper surface of the substrate, a first meniscus control feature on the substrate surrounding the die attach pad and defining a first encapsulant region of the upper surface of the substrate, and a second meniscus control feature on the substrate surrounding the first encapsulant region and defining a second encapsulant region of the upper surface of the substrate. The first and second meniscus control features may be substantially coplanar with the die attach pad. A packaged LED includes a submount as described above and further includes an LED chip on the die attach pad, a first encapsulant on the substrate within the first encapsulant region, and a second encapsulant on the substrate within the second encapsulant region and covering the first encapsulant. Method embodiments are also disclosed.

Claims

1. A packaged light emitting device comprising:

a substrate having an upper surface;

a solid state light emitting device on the substrate;

a transparent dam on the substrate defining a cavity above the solid state light emitting device, the transparent dam; and

an encapsulant within the cavity.

2. The packaged light emitting device of claim 1, further comprising a die attach pad on the upper surface of the substrate, wherein the solid state lighting device is on the die attach pad.

3. The packaged light emitting device of claim 1, wherein the transparent dam has a first index of refraction and the encapsulant has a second index of refraction that is different from the first index of refraction.

4. The packaged light emitting device of claim 3, wherein the second index of refraction is higher than the first index of refraction.

5. The packaged light emitting device of claim 3, wherein the encapsulant comprises a first encapsulant, the method further comprising:

a meniscus control feature on the upper surface of the substrate and surrounding the transparent dam; and

a second encapsulant on the substrate within a region defined by the third meniscus control feature, the third encapsulant covering the transparent dam and the first encapsulant and having a third index of refraction that is different from the first index of refraction or the second index of refraction.

6. The packaged light emitting device of claim 5, wherein the third index of refraction is higher than the first index of refraction.

7. The packaged light emitting device of claim 5, wherein the third index of refraction is higher than the second index of refraction.

8. packaged light emitting device of claim 5, wherein the third index of refraction is higher than the first index of refraction and is the same as the second index of refraction.

9. The packaged light emitting device of claim 3, wherein the second encapsulant comprises silicone gel and/or epoxy resin.

10. The packaged light emitting device of claim 3, wherein the second encapsulant comprises a second wavelength conversion material.

11. The packaged light emitting device of claim 1, wherein the transparent dam is toroidal.

12. The packaged light emitting device of claim 1, wherein the transparent dam comprises cured encapsulant material.

13. The packaged light emitting device of claim 1, wherein the transparent dam and/or the encapsulant comprises silicone gel and/or epoxy resin.

14. The packaged light emitting device of claim 1, wherein the encapsulant comprises a first wavelength conversion material and the transparent dam comprises a second wavelength conversion material.

15. A method of forming a packaged light emitting device, comprising:

forming a transparent dam on the upper surface of the substrate that defines a cavity above a die attach region on the upper surface of the substrate;

mounting a solid state light emitting device on the die attach region in the encapsulant region; and

dispensing an encapsulant material over the solid state lighting device within the cavity defined by the transparent dam.

16. The method of claim 15, further comprising a die attach pad in the die attach region, wherein the solid state lighting device is on the die attach pad.

17. The method of claim 15, wherein the transparent dam has a first index of refraction and the encapsulant has a second index of refraction that is different from the first index of refraction.

18. The method of claim 17, wherein the second index of refraction is higher than the first index of refraction.

19. The method of claim 17, further comprising:

forming a meniscus control feature on the substrate surrounding the transparent dam;

dispensing a second encapsulant material within a region defined by the third meniscus control feature, wherein the second encapsulant material has a third index of refraction that is different from the first index of refraction or the second index of refraction; and

curing the second encapsulant material.

20. The method of claim 19, wherein the third index of refraction is higher than the first index of refraction.

21. The method of claim 19, wherein the third index of refraction is higher than the second index of refraction.

22. The method of claim 19, wherein the third index of refraction is higher than the first index of refraction and is the same as the second index of refraction.

23. A packaged light emitting device comprising:

a substrate having an upper surface;

a die attach pad on the upper surface of the substrate, the die attach pad configured to receive a solid state light emitting device;

a first meniscus control feature on the substrate, the first meniscus control feature surrounding the die attach pad and configured to limit the flow of a liquid encapsulant material, and

a second meniscus control feature on the substrate, the second meniscus control feature surrounding the first meniscus control feature and configured to limit the flow of a liquid encapsulant material;

wherein the first meniscus control feature and the second meniscus control feature define an encapsulant region of the upper surface of the substrate surrounding the first encapsulant region;

a solid state light emitting device on the die attach pad;

a first encapsulant on the substrate within the encapsulant region defined by the first meniscus control feature and the second meniscus control feature, the first encapsulant having a first index of refraction and comprising a wavelength conversion material and defining a cavity above the solid state light emitting device;

a second encapsulant within the cavity, the second encapsulant having a second index of refraction that is different from the first index of refraction.