Packaged light emitting devices including multiple index lenses and methods of fabricating the same

• US 20070278512A1
• Filed: 05/31/2006
• Published: 12/06/2007
• Est. Priority Date: 05/31/2006
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Keller, Bernd, Loh, Ban P., Medendorp, Nicholas W.
• Granted Patent: US 7,646,035 B2
• Time in Patent Office: Days
• US Class Current: 257/99
• CPC Class Codes: B29C 45/14655 connected to or mounted on a carrier, e.g. lead frame
• CPC Class Codes: B29C 45/1671 with an insert
• CPC Class Codes: B29L 2011/0016 Lenses
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0052 the light source comprising a laser diode coupling into light guides using intermediate optical elements G02B6/4204; semiconductor lasers having optical devices external to the laser cavity H01S5/005
• CPC Class Codes: G02B 19/0071 adapted to illuminate a complete hemisphere or a plane extending 360 degrees around the source
• CPC Class Codes: H01L 33/54 having a particular shape
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor

Abstract

A packaged light emitting device includes a substrate, a solid state light emitting device on the substrate, a first generally toroidal lens on the substrate and defining a cavity relative to the solid state light emitting device and having a first index of refraction, and a second lens at least partially within the cavity formed by the first lens and having a second index of refraction that is different from the first index of refraction. The second index of refraction may be higher than the first index of refraction. The lenses may be mounted on the substrate and/or may formed by dispensing and curing liquid encapsulant materials.

Claims

1-69. -69. (canceled)

70. A packaged light emitting device, comprising:

a substrate;

a solid state light emitting device on the substrate;

a first lens on the substrate and defining a cavity relative to the solid state light emitting device and having a first index of refraction; and

a second lens positioned at least partially within the cavity formed by the first lens and having a second index of refraction that is different from the first index of refraction.

71. The packaged light emitting device of claim 70, wherein the second index of refraction is higher than the first index of refraction.

72. The packaged light emitting device of claim 70, further comprising an encapsulant material between the solid state light emitting device and the second lens.

73. The packaged light emitting device of claim 70, wherein the substrate comprises a leadframe or a printed circuit board, wherein the packaged light emitting device further comprises a molded body on the substrate, and wherein the first lens is on the molded body.

74. The packaged light emitting device of claim 73, wherein the molded body includes at least one surface that extends along a surface of the substrate and at least one vertical sidewall extending from the surface and defining a mounting location for the first lens.

75. The packaged light emitting device of claim 73, wherein the molded body extends at least partially through the leadframe.

76. The packaged light emitting device of claim 70, wherein the first lens includes a first mating surface and the second lens includes a second mating surface that is in contact with the first mating surface of the first lens.

77. The packaged light emitting device of claim 70, wherein the second lens is attached to the first lens using an adhesive encapsulant.

78. The packaged light emitting device of claim 77, wherein the adhesive encapsulant has an index of refraction that is substantially the same as the first index of refraction or the second index of refraction.

79. The packaged light emitting device of claim 70, further comprising a third lens positioned on the second lens and having a third index of refraction.

80. The packaged light emitting device of claim 79, wherein the third index of refraction is higher than the first index of refraction.

81. The packaged light emitting device of claim 80, wherein the third index of refraction is higher than the second index of refraction.

82. The packaged light emitting device of claim 80, wherein the third index of refraction is higher than the first index of refraction and is the same as the second index of refraction.

83. A solid state luminaire comprising a packaged light emitting device as recited in claim 70.

84. A backlight panel for a display comprising a packaged light emitting device as recited in claim 70.

85. A lens for a packaged light emitting device, comprising:

a generally toroidal side lens defining a cavity therein and having a first index of refraction; and

a core lens positioned at least partially within the cavity formed by the side lens and having a second index of refraction that is different from the first index of refraction.

86. The lens of claim 85, wherein the second index of refraction is higher than the first index of refraction.

87. The lens of claim 85, further comprising a third lens positioned on the second lens and having a third index of refraction.

88. The lens of claim 87, wherein the third index of refraction is higher than the first index of refraction.

89. The lens of claim 88, wherein the third index of refraction is higher than the second index of refraction.

90. The lens of claim 88, wherein the third index of refraction is higher than the first index of refraction and is the same as the second index of refraction.

91. 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 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.

92. The packaged light emitting device of claim 91, wherein the second index of refraction is higher than the first index of refraction.

93. The packaged light emitting device of claim 91, further comprising:

a third meniscus control feature surrounding the second meniscus control feature; and

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

94. The packaged light emitting device of claim 93, wherein the third index of refraction is higher than the first index of refraction.

95. The packaged light emitting device of claim 93, wherein the third index of refraction is higher than the second index of refraction.

96. The packaged light emitting device of claim 93, wherein the third index of refraction is higher than the first index of refraction and is the same as the second index of refraction.

97. The packaged light emitting device of claim 91, wherein the first encapsulant and/or the second encapsulant comprises silicone gel and/or epoxy resin.

98. The packaged light emitting device of claim 91, wherein the first encapsulant and/or the second encapsulant comprises a wavelength conversion material.

99. The packaged light emitting device of claim 93, wherein the third encapsulant comprises silicone gel and/or epoxy resin.

100. The packaged light emitting device of claim 93, wherein the third encapsulant comprises a wavelength conversion material.

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

forming a patterned metal film on a substrate, the patterned metal film including a die attach pad;

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

forming a second meniscus control feature on the substrate surrounding the first encapsulant region and configured to limit the flow of 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;

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

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

at least partially curing the first encapsulant material; and

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

102. The method of claim 101, wherein the second index of refraction is higher than the first index of refraction.

103. The method of claim 101, further comprising:

forming a third meniscus control feature on the substrate surrounding the second meniscus control feature;

dispensing a third encapsulant material within a region defined by the third meniscus control feature, wherein the third 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 third encapsulant material.

104. The method of claim 103, wherein the third index of refraction is higher than the first index of refraction.

105. The method of claim 103, wherein the third index of refraction is higher than the second index of refraction.

106. The method of claim 103, wherein the third index of refraction is higher than the first index of refraction and is the same as the second index of refraction.