Light emitting diode (LED) devices, systems, and methods

• US 9,111,778 B2
• Filed: 01/21/2011
• Issued: 08/18/2015
• Est. Priority Date: 06/05/2009
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Emerson, David T., Bergmann, Michael J., Hussell, Christopher P.
• Primary Examiner(s): POTTER, ROY KARL
• Application Number:
  US13/011,609
• Publication Number:
  US 20120153317A1
• Time in Patent Office: 1,670 Days
• Field of Search: 257/88, 257/89, 257/98, 257/E23.055, 438/28
• US Class Current: 1/1
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133608 including particular frames or supporting means
• CPC Class Codes: H01L 2224/29144 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/2929 with a principal constituent of the material being a polymer, e.g. polyester, phenolic based polymer, epoxy
• CPC Class Codes: H01L 2224/29399 Coating material
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/49113 the connectors connecting different bonding areas on the semiconductor or solid-state body to a common bonding area outside the body, e.g. converging wires
• CPC Class Codes: H01L 2224/83192 wherein the layer connectors are disposed only on another item or body to be connected to the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/92247 the second connecting process involving a wire connector
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/49 of a plurality of wire connectors
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 2924/00014 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 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/0105 Tin [Sn]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/01322 Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/0665 : Epoxy resin
• CPC Class Codes: H01L 2924/10157 : at the active surface
• CPC Class Codes: H01L 2924/10158 : at the passive surface
• CPC Class Codes: H01L 2924/12032 : Schottky diode
• CPC Class Codes: H01L 2924/12035 : Zener diode
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 33/486 : adapted for surface mounting
• 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 33/642 : characterized by the shape

Abstract

Light emitting diode (LED) devices, systems, and methods are disclosed. In one aspect, an illumination panel can be configured to provide backlighting for a liquid crystal display (LCD) panel. The illumination panel can include one or more LEDs arranged in an array. The one or more LEDs can be attached using metal-to-metal die attach methods over an illumination panel, or attached within packages disposed over the illumination panel. In one aspect, the one or more LEDs can be attached using robust metal-to-metal die attach techniques and/or materials disclosed herein.

Claims

1. A backlighting device for use with a display panel, the backlighting device comprising:

one or more light emitting diodes (LEDs) for backlighting a display panel, the one or more LEDs attached to a substrate by eutectic die attach, by thermal compression die attach, or by non-eutectic metal-to-metal die attach; and

the one or more LEDs comprising an array of LEDs operable for providing substantially uniform illumination to the display panel.

2. The device according to claim 1, wherein eutectic die attach comprises flux eutectic die attach.

3. The device according to claim 1, wherein non-eutectic die attach comprises a metal-assist.

4. The device according to claim 3, wherein the metal-assist comprises AuSn paste or Ag epoxy.

5. The device according to claim 1, wherein the substrate comprises an illumination panel disposed behind the display panel.

6. The device according to claim 1, wherein the substrate comprises a mounting surface within an LED package.

7. The device according to claim 1, wherein the one or more LEDs comprises a substantially vertical side disposed between an upper surface and a bonding surface.

8. The device according to claim 1, wherein the one or more LEDs comprises a beveled side inclined between an upper surface and a bonding surface.

9. The device according to claim 8, wherein the upper surface comprises a first surface area and the bonding surface comprises a second surface area.

10. The device according to claim 9, wherein the first surface area is larger than the second surface area.

11. The device according to claim 9, wherein the first surface area is smaller than the second surface area.

12. The device according to claim 1, wherein the one or more LEDs comprise a plurality of red, green, and blue LEDs.

13. The device according to claim 5, wherein at least one optical layer is disposed between the illumination panel and the LCD panel.

14. The device according to claim 1, wherein a bonding surface of the LEDs attaches to the substrate, the bonding surface comprising a layer of gold/tin (Au/Sn).

15. The device according to claim 14, wherein the bonding surface comprises a layer 80/20 AuSn.

16. The device according to claim 1, wherein a bonding surface of the LEDs attaches to the substrate, the bonding surface comprising a layer of tin (Sn).

17. The device according to claim 16, wherein the bonding surface comprises a layer having a thickness equal to or at least greater than approximately 0.5 μ

m Sn.

102. The device according to claim 1, comprising a minimum of approximately 65 CRI for Cool White (CW) color points or a minimum of approximately 80 CRI for Warm White (WW) color points.

18. A backlighting device for use with a display panel, the backlighting device comprising:

one or more light emitting diodes (LEDs) for backlighting a display panel, the one or more LEDs attached to a substrate at a mounting temperature of approximately 280°

Celsius (°

C.) or greater;

the one or more LEDs operable for providing substantially uniform illumination to the display panel; and

the device comprising a minimum of approximately 65 CRI for Cool White (CW) color points or a minimum of approximately 80 CRI for Warm White (WW) color points.

19. The device according to claim 18, wherein the one or more LEDs attach to a substrate by eutectic die attach, by thermal compression die attach, or by non-eutectic metal-to-metal die attach.

20. The device according to claim 19, wherein eutectic die attach comprises flux eutectic die attach.

21. The device according to claim 19, wherein non-eutectic die attach comprises a metal-assist.

22. The device according to claim 21, wherein the metal-assist comprises AuSn paste or Ag epoxy.

23. The device according to claim 18, wherein the substrate comprises an illumination panel disposed behind the display panel.

24. The device according to claim 18, wherein the substrate comprises a mounting surface within an LED package.

25. The device according to claim 18, wherein the one or more LEDs comprises an array of LEDs.

26. The device according to claim 18, wherein the one or more LEDs comprises a beveled side inclined between an upper surface and a bonding surface.

27. The device according to claim 18, wherein the one or more LEDs comprises a substantially vertical side disposed between an upper surface and a bonding surface.

28. The device according to claim 26, wherein the upper surface comprises a first surface area and the bonding surface comprises a second surface area.

29. The device according to claim 28, wherein the first surface area is larger than the second surface area.

30. The device according to claim 28, wherein the first surface area is smaller than the second surface area.

31. The device according to claim 18, wherein the one or more LEDs comprise a plurality of red, green, and blue LEDs.

32. The device according to claim 23, wherein at least one optical layer is disposed between the illumination panel and the display panel.

33. The device according to claim 18, wherein a bonding surface of the LEDs attaches to the substrate, the bonding surface comprising a layer of gold/tin (Au/Sn).

34. The device according to claim 33, wherein the bonding surface comprises a layer 80/20 AuSn.

35. The device according to claim 18, wherein a bonding surface of the LEDs attaches to the substrate, the bonding surface comprising a layer of tin (Sn).

36. The device according to claim 35, wherein the bonding surface comprises a layer having a thickness equal to or at least greater than approximately 0.5 μ

m Sn.

37. A backlighting system comprising:

a display panel for displaying an image;

an illumination panel comprising one or more light emitting diodes (LEDs) attached to a substrate;

the one or more LEDs attached to the substrate by eutectic die attach, thermal compression die attach, or by non-eutectic metal-to-metal die attach;

the one or more LEDs operable for providing substantially uniform illumination to the display panel; and

the system comprising a minimum of approximately 65 CRI for Cool White (CW) color points or a minimum of approximately 80 CRI for Warm White (WW) color points.

38. The system according to claim 37, wherein eutectic die attach comprises flux eutectic die attach.

39. The system according to claim 37, wherein non-eutectic die attach comprises a metal-assist.

40. The system according to claim 39, wherein the metal-assist comprises AuSn paste or Ag epoxy.

41. The system according to claim 37, wherein the substrate comprises the illumination panel.

42. The system according to claim 37, wherein the substrate comprises a mounting surface within an LED package.

43. The system according to claim 41, wherein the illumination panel comprises an array of LEDs.

44. The system according to claim 37, wherein the one or more LEDs comprise a beveled side inclined between an upper surface and a bonding surface.

45. The system according to claim 37, wherein the one or more LEDs comprises a substantially vertical side disposed between an upper surface and a bonding surface.

46. The system according to claim 44, wherein the upper surface comprises a first surface area and the bonding surface comprises a second surface area.

47. The system according to claim 46, wherein the first surface area is larger than the second surface area.

48. The system according to claim 37, wherein the first surface area is smaller than the second surface area.

49. The system according to claim 37, wherein the one or more LEDs comprise a plurality of red, green, and blue LEDs.

50. The system according to claim 37, wherein at least one optical film is disposed between the illumination panel and the display panel.

51. The system according to claim 37, wherein a bonding surface of the LEDs attaches to the substrate, the bonding surface comprising a layer of gold/tin (Au/Sn).

52. The system according to claim 51, wherein the bonding surface comprises a layer 80/20 AuSn.

53. The system according to claim 37, wherein a bonding surface of the LEDs attaches to the substrate, the bonding surface comprising a layer of tin (Sn).

54. The system according to claim 53, wherein the bonding surface comprises a layer having a thickness equal to or at least greater than approximately 0.5 μ

m Sn.

55. A backlighting system comprising:

a display panel for displaying an image;

an illumination panel comprising an array of light emitting diodes (LEDs) attached to a substrate;

the array of LEDs attached to the substrate at a mounting temperature greater than a melting temperature of a bonding layer of the LEDs; and

the array of LEDs operable for providing substantially uniform illumination to the display panel.

56. The system according to claim 55, wherein the array of LEDs is attached to the substrate at a mounting temperature of at least approximately 10°

C. or greater than a melting temperature of a bonding layer of the LEDs.

57. The system according to claim 55, wherein the array of LEDs is attached to the substrate at a mounting temperature of at least approximately 20°

C. or greater than a melting temperature of a bonding layer of the LEDs.

58. The system according to claim 55, wherein the substrate comprises the illumination panel.

59. The system according to claim 55, wherein the substrate comprises a mounting surface within an LED package.

60. The system according to claim 55, wherein each LED of the array of LEDs comprises a beveled side inclined between an upper surface and a bonding surface.

61. The system according to claim 55, wherein each LED of the array of LEDs comprises a substantially vertical side disposed between an upper surface and a bonding surface.

62. The system according to claim 60, wherein the upper surface comprises a first surface area and the bonding surface comprises a second surface area.

63. The system according to claim 62, wherein the first surface area is larger than the second surface area.

64. The system according to claim 62, wherein the first surface area is smaller than the second surface area.

65. The system according to claim 55, wherein the array of LEDs comprise a plurality of red, green, and blue LEDs.

66. The system according to claim 55, wherein at least one optical layer is disposed between the illumination panel and the display panel.

67. The system according to claim 55, wherein a bonding surface of the LEDs attaches to the substrate, the bonding surface comprising a layer of gold/tin (Au/Sn).

68. The system according to claim 67, wherein the bonding surface comprises a layer 80/20 AuSn.

69. The system according to claim 55, wherein a bonding surface of the LEDs attaches to the substrate, the bonding surface comprising a layer of tin (Sn).

70. The system according to claim 67, wherein the bonding surface comprises a layer having a thickness equal to or at least greater than approximately 0.5 μ

m Sn.

103. The system according to claim 55, comprising a minimum of approximately 65 CRI for Cool White (CW) color points or a minimum of approximately 80 CRI for Warm White (WW) color points.

71. A method for backlighting a display panel, the method comprising:

providing a backlighting device comprising;

one or more light emitting diodes (LEDs) for backlighting a display panel, the one or more LEDs attached to a substrate by eutectic die attach, thermal compression die attach, or by non-eutectic metal-to-metal die attach; and

the one or more LEDs operable for providing substantially uniform illumination to the display panel; and

positioning the one or more LEDs with respect to the display panel for providing substantially uniform backlighting illumination to the display panel, wherein positioning the one or more LEDs comprises positioning the LEDs spaced apart a gap from the display panel.

72. The method according to claim 71, providing a backlighting device comprises the one or more LEDs attached to a substrate by eutectic die attach comprising a flux eutectic die attach.

73. The method according to claim 71, providing a backlighting device comprises the one or more LEDs attached to a substrate by non-eutectic die attach comprising a metal-assist die attach.

74. The method according to claim 73, wherein the metal-assist die attach comprises AuSn paste or Ag epoxy.

75. The method of claim 71, wherein positioning the one or more LEDs comprises positioning the LEDs directly behind the display panel.

76. The method of claim 71, wherein positioning the one or more LEDs comprises positioning the LEDs about a side edge of the display panel.

77. The method of claim 71, wherein the one or more LEDs are attached directly to the substrate, and the substrate comprises an illumination panel.

78. The method of claim 71, wherein the one or more LEDs are attached directly to the substrate, and the substrate comprises an LED package disposed over an illumination panel.

79. A method for backlighting a display panel, the method comprising:

providing a backlighting device comprising;

one or more light emitting diodes (LEDs) for backlighting a display panel, the one or more LEDs attached to a substrate at a mounting temperature of approximately 280°

Celsius (°

C.) or greater; and

the one or more LEDs operable for providing substantially uniform illumination to the display panel; and

positioning the one or more LEDs with respect to the display panel for providing substantially uniform backlighting illumination to the display panel.

80. The method of claim 79, wherein positioning the one or more LEDs comprises positioning the LEDs directly behind the display panel.

81. The method of claim 79, wherein positioning the one or more LEDs comprises positioning the LEDs about an edge of the display panel.

82. The method of claim 79, wherein positioning the one or more LEDs comprises positioning the LEDs spaced apart by a gap from the display panel.

83. The method of claim 79, wherein the one or more LEDs are attached directly to the substrate, and the substrate comprises an illumination panel.

84. The method of claim 79, wherein the one or more LEDs are attached directly to the substrate, and the substrate comprises an LED package disposed over an illumination panel.

85. A method for backlighting a display panel, the method comprising:

providing a backlighting system comprising;

a display panel for displaying an image;

an illumination panel comprising one or more light emitting diodes (LEDs) attached to a substrate;

the one or more LEDs attached to the substrate by eutectic die attach, thermal compression die attach, or by non-eutectic metal-to-metal die attach; and

the one or more LEDs operable for providing substantially uniform illumination to the display panel; and

positioning the one or more LEDs with respect to the display panel for providing substantially uniform backlighting illumination to the display panel.

86. The method of claim 85, wherein positioning the one or more LEDs comprises positioning the LEDs directly behind the display panel.

87. The method of claim 85, wherein positioning the one or more LEDs comprises positioning the LEDs about an edge of the display panel.

88. The method of claim 85, wherein positioning the one or more LEDs comprises positioning the LEDs spaced apart a gap from the display panel.

89. The method of claim 85, wherein the one or more LEDs are attached directly to the substrate, and the substrate comprises an illumination panel.

90. The method of claim 85, wherein the one or more LEDs are attached directly to the substrate, and the substrate comprises an LED package disposed over an illumination panel.

91. The method according to claim 85, providing a backlighting system comprises the one or more LEDs attached to a substrate by eutectic die attach comprising a flux eutectic die attach.

92. The method according to claim 85, providing a backlighting system comprises the one or more LEDs attached to a substrate by non-eutectic die attach comprising a metal-assist die attach.

93. The method according to claim 92, wherein the metal-assist die attach comprises AuSn paste or Ag epoxy.

94. A method for backlighting a display panel, the method comprising:

providing a backlighting system comprising;

a display panel for displaying an image;

an illumination panel comprising one or more light emitting diodes (LEDs) attached to a substrate;

the one or more LEDs attached to the substrate at a mounting temperature greater than a melting temperature of a bonding layer of the LEDs;

the one or more LEDs operable for providing substantially uniform illumination to the display panel; and

positioning the one or more LEDs with respect to the display panel for providing substantially uniform backlighting illumination to the display panel.

95. The method of claim 94, wherein providing a backlighting system comprises the one or more LEDs attached to the substrate at a mounting temperature greater than at least approximately 10°

Celsius (°

C.).

96. The method of claim 94, wherein providing a backlighting system comprises the one or more LEDs attached to the substrate at a mounting temperature greater than at least approximately 20′

Celsius (°

C.).

97. The method of claim 94, wherein positioning the one or more LEDs comprises positioning the LEDs directly behind the display panel.

98. The method of claim 94, wherein positioning the one or more LEDs comprises positioning the LEDs about an edge of the display panel.

99. The method of claim 94, wherein positioning the one or more LEDs comprises positioning the LEDs spaced apart by a gap from the display panel.

100. The method of claim 94, wherein the one or more LEDs are attached directly to the substrate, and the substrate comprises an illumination panel.

101. The method of claim 94, wherein the one or more LEDs are attached directly to the substrate, and the substrate comprises an LED package disposed over an illumination panel.

104. A light emitting device for a lighting fixture, the light emitting device comprising:

a package for housing one or more light emitting diodes (LEDs);

the one or more LEDs attached to a substrate of the package by eutectic die attach, thermal compression die attach, or by non-eutectic metal-to-metal die attach; and

the light emitting device comprising a minimum of approximately 65 CRI for Cool White (CW) color points or a minimum of approximately 80 CRI for Warm White (WW) color points.

105. The light emitting device of claim 104, wherein the lighting fixture comprises a lighting fixture for a panel display system.

106. The light emitting device of claim 104, wherein the panel display system comprises a backlighting system.

107. The light emitting device of claim 104, wherein the non-eutectic metal-to-metal die attach comprises metal-assisted die attach using gold/tin (Au/Sn) paste or silver (Ag) epoxy.

108. The light emitting device of claim 104, wherein the package comprises a lens.

109. The light emitting device of claim 104, wherein the one or more LEDs comprise at least two LEDs.

110. The light emitting device of claim 104, wherein the one or more LEDs comprise beveled lateral sides.

111. The light emitting device of claim 104, wherein the one or more LEDS comprise straight cut lateral sides.

112. The light emitting device of claim 104, wherein the substrate comprises a thermal transfer element.

113. The light emitting device of claim 104, wherein the one or more LEDs are electrically connected in parallel, in series, or a combination of both.

114. The light emitting device of claim 104, wherein the eutectic die attach comprises flux eutectic die attach.

121. The light emitting device of claim 111, where the lateral sides are inclined between the bonding surface and the upper surface such that the upper surface has an upper surface area which is larger than a surface area of the bonding surface.

122. The light emitting device of claim 111, where the lateral sides are inclined between the bonding surface and the upper surface such that the upper surface has an upper surface area which is smaller than a surface area of the bonding surface.

123. The light emitting device of claim 111, wherein the mounting substrate comprises a thermal transfer element.

124. The light emitting device of claim 111, wherein the package defines a cavity in which the one or more LEDs are disposed.

125. The light emitting device of claim 111, wherein the one or more LEDS comprise substantially vertical lateral sides.

126. The light emitting device according to claim 111, comprising a minimum of approximately 65 CRI for Cool White (CW) color points or a minimum of approximately 80 CRI for Warm White (WW) color points.

115. A light emitting device for a lighting fixture, the light emitting device comprising:

a package for housing one or more light emitting diodes (LEDs);

the one or more LEDs comprising a bonding surface disposed opposite an upper surface of the one or more LEDS, an inclined lateral side extending between the bonding surface and the upper surface, and the bonding surface comprising a bonding layer attached to a mounting substrate of the package by eutectic die attach, thermal compression die attach, or by non-eutectic metal-to-metal die attach;

wherein the bonding surface the one or more LEDs comprises at least a portion of a substrate, a p-side, a n-side, or each of the p- and n-sides of the LED.

116. The light emitting device of claim 115, wherein eutectic die attach comprises flux eutectic die attach.

117. The light emitting device of claim 115, wherein the non-eutectic metal-to-metal die attach comprises metal-assisted die attach using gold/tin (Au/Sn) paste or silver (Ag) epoxy.

118. The light emitting device of claim 115, wherein the substrate comprises a growth substrate or a carrier substrate.

119. The light emitting device of claim 115, wherein the package comprises a lens.

120. The light emitting device of claim 115, wherein the one or more LEDs comprise at least two LEDs.