LIGHT EMITTING DEVICES AND SUBSTRATES WITH IMPROVED PLATING

• US 20130328070A1
• Filed: 03/14/2013
• Published: 12/12/2013
• Est. Priority Date: 06/06/2012
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Hussell, Christopher P., Reiherzer, Jesse Colin, Welch, Erin
• Granted Patent: US 9,590,155 B2
• Time in Patent Office: Days
• US Class Current: 257/88
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 2933/0033 relating to semiconductor body packages
• 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: H01L 33/641 characterized by the materials
• CPC Class Codes: H05K 2201/0341 Intermediate metal, e.g. before reinforcing of conductors by plating
• CPC Class Codes: H05K 2201/099 Coating over pads, e.g. solder resist partly over pads
• CPC Class Codes: H05K 2201/10106 Light emitting diode [LED]
• CPC Class Codes: H05K 2201/2054 Light-reflecting surface, e.g. conductors, substrates, coatings, dielectrics
• CPC Class Codes: H05K 2203/073 Displacement plating, substitution plating or immersion plating, e.g. for finish plating
• CPC Class Codes: H05K 2203/1461 Applying or finishing the circuit pattern after another process, e.g. after filling of vias with conductive paste, after making printed resistors
• CPC Class Codes: H05K 3/244 Finish plating of conductors, especially of copper conductors, e.g. for pads or lands selective plating methods H05K3/243; finish plating of conductors made by printing techniques H05K3/246; solder as finish H05K3/3457, e.g. by plating H05K3/3473

Abstract

Light emitting devices and substrates are provided with improved plating. In one embodiment, a light emitting device can include a submount and one or more light emitting diodes (LED) chips disposed over the submount. In one embodiment, the submount can include a copper (Cu) substrate, a first metallic layer of material that is highly reflective disposed over the Cu substrate for increased brightness of the device, and a second metallic layer disposed between the Cu substrate and the first metallic layer for forming a barrier therebetween.

Claims

1. A light emitting device comprising:

a copper (Cu) substrate;

a first metallic layer comprising a reflective metal disposed over the Cu substrate for increasing brightness of the device;

a second metallic layer disposed between the Cu substrate and the first metallic layer for forming a diffusion barrier therebetween; and

one or more light emitting diodes (LED) chips disposed over the submount.

2. The device of claim 1, wherein the first layer comprises immersion silver (Ag).

3. The device of claim 1, wherein the second metallic layer comprises electroless nickel (Ni).

4. The device of claim 1, wherein the Cu substrate comprises one or more electrically conductive traces and a conductive pad over which the first and second layers are disposed.

5. The device of claim 4, wherein the first and second metallic layers are disposed over a vertical edge portion of the conductive pad or the one or more electrically conductive traces.

6. The device of claim 4, wherein a gap is disposed between the one or more electrically conductive traces and the conductive pad.

7. The device of claim 6, wherein the gap between the conductive pad and the one or more electrically conductive traces is smaller in width than a second gap between portions of the first and second layers disposed over each of the conductive pad and the one or more electrically conductive traces.

8. The device of claim 1, wherein the submount further comprises a layer non-metallic reflective material disposed over a portion of the first metallic layer.

9. The device of claim 8, wherein the non-metallic reflective material comprises solder mask.

10. The device of claim 1, wherein the submount further comprises a layer of solder mask disposed over a portion of the second metallic layer.

11. The device of claim 1, wherein a retention material is disposed about the one or more LED chips.

12. The device of claim 11, wherein an encapsulant filling material is disposed within an inner wall of the retention material.

13. The device of claim 12, wherein one or more phosphors are disposed in the encapsulant.

14. The device of claim 1, wherein the submount further comprises a ceramic substrate over which the Cu substrate is disposed.

15. The device of claim 14, wherein one or more conductive vias are disposed through the ceramic substrate and electrically communicate with the Cu substrate.

16. The device of claim 14, further comprising a lens disposed over the one or more LED chips.

17. A method of providing an LED device, the method comprising:

providing a substrate;

plating a first metallic layer over the substrate via an electroless plating process, wherein the first metallic layer comprises a barrier layer of material prohibiting diffusion into the substrate;

plating a second metallic layer of material over the first layer metallic layer of material via an immersion plating process, wherein the second metallic layer of material is reflective; and

providing one or more light emitting diode (LED) chips for placement over the substrate.

18. The method of claim 17, wherein the substrate comprises Cu.

19. The method of claim 17, further comprising etching the substrate to form one or more electrically conductive traces and a conductive pad.

20. The method of claim 17, wherein plating the second metallic layer comprises plating a vertical edge portion of the conductive pad or the one or more electrically conductive traces.

21. The method of claim 17, further comprising performing an initial etching step to form a first horizontally disposed gap between portions of the first and second metallic layers.

22. The method of claim 20, further comprising performing a second etching step to form a second horizontally disposed gap between portions of the substrate.

23. The method of claim 21, wherein the second gap is smaller than the first gap.

24. The method of claim 17, further comprising depositing a layer of non-metallic reflective material over a portion of the second metallic layer of material.

25. The method of claim 17, further comprising dispensing a retention material about the one or more LED chips.

26. A method comprising:

providing a copper (Cu) substrate;

immersion plating a first layer of material over the Cu substrate;

etching a portion of the first layer through a first mask;

etching a portion of the Cu substrate through a second mask, wherein the Cu substrate is greater in surface area than first layer of material; and

providing one or more light emitting diode (LED) chips for placement over the Cu substrate.

27. The method of claim 26, further comprising plating a barrier layer of material over the Cu substrate prior to immersion plating the first layer.

28. The method of claim 27, wherein plating the barrier layer comprises electroless plating the barrier layer.

29. The method of claim 26, further comprising applying a non-metallic reflective layer over a portion of the first layer of material.

30. The method of claim 26, wherein a retention material is disposed about the one or more LED chips.

31. The method of claim 30, wherein an encapsulant is disposed within an inner wall of the retention material.

32. The method of claim 26, further comprising providing a ceramic submount and providing the Cu substrate over the ceramic submount.

33. A method comprising:

providing a substrate;

etching a portion of the substrate such that a gap forms between a first portion and at least a second portion;

applying a reflective layer of metal over a vertical edge of each of the first and second portions; and

providing one or more light emitting diode (LED) chips for placement over the conductive pad.

34. The method of claim 33, wherein the first portion comprises a conductive pad and the second portion comprises a metallic trace.

35. The method of claim 33, further comprising plating a barrier layer over the substrate prior to applying the reflective layer.

36. The method of claim 33, wherein applying the reflective layer comprises immersion plating the reflective layer.

37. The method of claim 35, wherein plating the barrier layer comprises electroless plating the barrier layer.

38. The method of claim 35, wherein the barrier layer is plated over the vertical edge of each of the first and second portions.

39. The method of claim 33, further comprising applying a non-metallic layer of reflective material in a gap between the first and second portions of the substrate.

40. The method of claim 33, further comprising dispensing a retention material about the LED chips.

41. The method of claim 33, further comprising plating the Cu substrate over a ceramic submount.

42. A submount for a device with a light emitting diode (LED), the submount comprising:

a copper (Cu) substrate;

a layer of immersion silver (Ag) disposed over the Cu substrate; and

a layer of electroless nickel (Ni) disposed between the Cu substrate and the immersion Ag.

43. The submount of claim 42, further comprising an LED chip mounted to the Cu substrate.

44. A method of providing an LED device, the method comprising:

providing a substrate;

plating a first layer of material over the substrate via an immersion plating process, wherein the first layer comprises a reflective metal;

applying a second layer of material over the first layer of material, wherein the second layer of material comprises a non-metallic reflective material.

45. The method according to claim 44, wherein the second layer comprises plastic.

46. The method according to claim 44, wherein the second layer comprises a solder mask.

47. The method according to claim 44, wherein the first layer comprises plastic.

48. The method according to claim 44, further comprising plating a barrier layer of material between the substrate and the first layer of material, wherein the barrier layer of material is adapted to prohibit diffusion between the substrate and the first layer of material.

49. The method according to claim 48, wherein the barrier layer comprises Ni.

50. The method according to claim 48, wherein plating the barrier layer comprises electroless plating the barrier layer.

51. The method according to claim 44, wherein the substrate comprises copper (Cu).