LED WITH PHOSPHOR TILE AND OVERMOLDED PHOSPHOR IN LENS

• US 20110057205A1
• Filed: 11/15/2010
• Published: 03/10/2011
• Est. Priority Date: 11/15/2004
• Status: Abandoned Application

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Mueller, Gerd, West, Robert Scott, Mueller-Mach, Regina, Lim, Tze-Sen, Eberle, Stefan, Martin, Paul S., Basin, Grigoriy
• Application Number:
  US12/945,962
• Publication Number:
  US 20110057205A1
• Time in Patent Office: Days
• US Class Current: 257/84
• CPC Class Codes: B29C 41/14 Dipping a core B29C41/10 takes precedence
• CPC Class Codes: B29C 41/20 incorporating preformed parts or layers, e.g. moulding inserts or for coating articles
• CPC Class Codes: B29C 41/22 Making multilayered or multicoloured articles
• CPC Class Codes: B29K 2995/0031 Refractive
• CPC Class Codes: B29L 2011/00 Optical elements, e.g. lenses, prisms
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45139 Silver (Ag) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/73204 the bump connector being embedded into the layer connector
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/81 using a bump connector
• CPC Class Codes: H01L 2224/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 24/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• 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 2924/00011 Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01023 : Vanadium [V]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01049 : Indium [In]
• CPC Class Codes: H01L 2924/01055 : Cesium [Cs]
• CPC Class Codes: H01L 2924/01058 : Cerium [Ce]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/15787 : Ceramics, e.g. crystalline carbides, nitrides or oxides
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/1815 : Shape
• CPC Class Codes: H01L 2924/207 : Diameter ranges
• CPC Class Codes: H01L 2924/351 : Thermal stress
• CPC Class Codes: H01L 2933/0041 : relating to wavelength conversion elements
• CPC Class Codes: H01L 33/504 : Elements with two or more wavelength conversion materials
• CPC Class Codes: H01L 33/505 : characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/54 : having a particular shape
• CPC Class Codes: H01L 33/56 : Materials, e.g. epoxy or silicone resin

Abstract

Overmolded lenses and certain fabrication techniques are described for LED structures. In one embodiment, thin YAG phosphor plates are formed and affixed over blue LEDs mounted on a submount wafer. A clear lens is then molded over each LED structure during a single molding process. The LEDs are then separated from the wafer. The molded lens may include red phosphor to generate a warmer white light. In another embodiment, the phosphor plates are first temporarily mounted on a backplate, and a lens containing a red phosphor is molded over the phosphor plates. The plates with overmolded lenses are removed from the backplate and affixed to the top of an energizing LED. A clear lens is then molded over each LED structure. The shape of the molded phosphor-loaded lenses may be designed to improve the color vs. angle uniformity. Multiple dies may be encapsulated by a single lens. In another embodiment, a prefabricated collimating lens is glued to the flat top of an overmolded lens.

Claims

1-12. -12. (canceled)

13. A light emitting diode (LED) structure comprising:

an LED emitting blue light or UV light on a submount;

a substantially flat phosphor layer overlying the LED;

a molded phosphor-loaded lens over the phosphor layer; and

a clear lens, containing no phosphor, molded over the LED and phosphor-loaded lens.

14. The structure of claim 13 wherein the phosphor layer is a phosphor plate that is affixed to the LED.

15. The structure of claim 13 wherein the phosphor-loaded lens is affixed to the LED with the phosphor layer adjacent the LED.

16. The structure of claim 13 wherein the phosphor layer contains YAG phosphor and the phosphor in the phosphor-load lens comprises red phosphor.

17. The structure of claim 13 wherein the LED in combination with the phosphor layer has a color temperature vs. viewing angle, and wherein the phosphor-loaded lens is shaped to increase uniformity of the color temperature vs. viewing angle.

18. The structure of claim 13 wherein the phosphor layer is a phosphor layer conformally coating the LED.

19. The structure of claim 13 wherein the combination of light from the LED, the phosphor layer, and the phosphor-loaded lens produces white light.

20-22. -22. (canceled)

23. A light emitting diode (LED) structure comprising:

an LED emitting blue light or UV light on a submount;

a molded first phosphor-loaded lens containing a first phosphor over the LED;

a molded second phosphor-loaded lens containing a second phosphor over the first phosphor-loaded lens;

a molded clear lens, containing no phosphor over the second phosphor-loaded lens.

24. The structure of claim 23 wherein the first phosphor is different from the second phosphor.

25. The structure of claim 23 wherein the LED in combination with the first phosphor-loaded lens has a color temperature vs. viewing angle, and wherein the second phosphor-loaded lens is shaped to increase uniformity of the color temperature vs. viewing angle.

26. A light emitting diode (LED) structure comprising:

an LED on a submount along with one or more semiconductor dice mounted on the submount; and

a single lens molded over the LED and the one or more semiconductor dice.

27. The structure of claim 26 further comprising a molded phosphor-loaded lens overlying the LED and the one or more semiconductor dice, where the single lens is molded over the phosphor-loaded lens.

28. The structure of claim 26 wherein the one or more semiconductor dice comprise one or more LEDs.

29. The structure of claim 26 wherein the one or more semiconductor dice comprise a plurality of LEDs emitting different colors.

30. The structure of claim 26 wherein the one or more semiconductor dice comprise a transient voltage suppressor.

31. The structure of claim 26 wherein the one or more semiconductor dice comprise a photodetector.

32. The structure of claim 26 wherein the single lens molded over the LED and the one or more semiconductor dice is not symmetrical about a central axis.

33. The structure of claim 26 wherein the single lens encapsulates the LED and the one or more semiconductor dice.

34. A light emitting diode (LED) structure comprising:

an LED mounted on a substrate;

a first lens molded over and encapsulating the LED, the lens having a substantially flat top; and

a prefabricated second lens affixed to the substantially flat top of the first lens.

35. The structure of claim 34 wherein the second lens is a collimating lens.

36. The structure of claim 34 wherein the second lens is a Fresnel lens.

37. The structure of claim 34 wherein the first lens has wall portions surrounding the substantially flat top such that a top of the wall portions is substantially coplanar with a top of the second lens.

38. The structure of claim 37 wherein the wall portions are angled

to reflect light from sides of the second lens away from the LED.

39. The structure of claim 34 wherein a surface of the second lens is approximately a same size as a surface of the LED.

40. The structure of claim 34 wherein the first lens contains phosphor and light from the LED energizes the phosphor and mixes with light generated by the phosphor.

41. The structure of claim 34 wherein the structure emits white light.

42. The structure of claim 41 wherein the structure is a flash in a camera.

43. The structure of claim 34 wherein the first lens comprises silicone.

44. A process for forming a light emitting diode (LED) structure comprising:

mounting an LED on a submount, wherein at least a first electrode on the LED is bonded to at least a second electrode on a surface of the submount, a void existing between the LED and the surface of the submount;

filling the void with an underfill material;

providing a mold having an indention corresponding to a lens;

filling the indention with a liquid lens material;

after the step of filling, immersing the LED and the underfill material into the liquid lens material in the mold, the underfill preventing the liquid lens material from entering the void;

curing the liquid lens material to encapsulate the LED and underfill material with a molded lens; and

removing the LED with the molded lens from the mold.

45. The method of claim 44 wherein a transparent substrate forms a top surface of the LED, wherein a portion of the underfill material is disposed on side surfaces of the LED, including the substrate.

46-49. -49. (canceled)

50. A light emitting diode (LED) structure comprising:

an LED on a submount;

a molded first lens over the LED, wherein the molded first lens has a plasma treated outer surface;

a molded second lens formed directly over the first lens, wherein the plasma treated outer surface of the first lens increases adherence of the first lens to the second lens.

51. A process for forming a light emitting diode (LED) structure comprising:

providing an arrangement of a plurality of LED dies mounted on a single submount substrate;

providing a first mold having first indentions in an arrangement corresponding to the arrangement of the plurality of LED dies, each first indentation corresponding to outer dimensions of a first lens to be formed over each of the LED dies mounted on the submount substrate;

aligning the submount substrate with respect to the first mold;

molding first lenses, not containing a phosphor, directly over each of the LED dies using the first mold;

providing a second mold having second indentions in an arrangement corresponding to the arrangement of the plurality of LED dies, each second indentation corresponding to outer dimensions of a second lens to be formed over each of the LED dies mounted on the submount substrate, dimensions of each second indention being larger than dimensions of each first indention;

aligning the submount substrate with respect to the second mold; and

molding second lenses, containing a phosphor, over each of the LED dies and first lenses using the second mold;

whereby inner dimensions of the second lenses over the LED dies are defined by outer dimensions of the first lenses over the LED dies, such that identical misalignments of the submount substrate with respect to the first mold and the second mold, within a range, do not affect a thickness of the second lenses.

52. The process of claim 51 wherein molding clear first lenses, not containing a phosphor, over each of the LED dies using the first mold comprises:

filling the first indentions with a first liquid lens material not containing a phosphor, prior to aligning the submount substrate with respect to the first mold;

immersing all the LED dies simultaneously into the first liquid lens material in the first mold; and

curing the first liquid lens material to form the first lens over each of the LED dies;

and wherein molding second lenses, containing a phosphor, over each of the LED dies and first lenses using the second mold comprises;

filling the second indentions with a second liquid lens material containing a phosphor, prior to aligning the submount substrate with respect to the second mold;

immersing all the LED dies and first lenses simultaneously into the second liquid lens material in the second mold; and

curing the second liquid lens material to form the second lens over each of the LED dies and over each of the first lenses.

53. The process of claim 51 further comprising dicing the substrate to form individual LED structures.

54. The process of claim 51 further comprising molding one or more additional lenses over the second lenses.

55. The process of claim 51 wherein the phosphor in the second lenses, in conjunction with light emitted by the LED dies, generates white light.

56. A light emitting diode (LED) structure comprising:

an LED die mounted on a submount substrate;

a first lens molded directly over the LED die using a first mold aligned to the substrate, the first lens containing no phosphor; and

a second lens molded directly over the first lens using a second mold aligned to the substrate, the second lens containing a phosphor,

whereby inner dimensions of the second lens over the LED die are defined by outer dimensions of the first lens over the LED die, such that identical misalignments of the substrate with respect to the first mold and the second mold, within a range, do not affect a thickness of the second lens.