(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2005/0218421 A1
`(43) Pub. Date:
`Oct. 6, 2005
`Andrews et al.
`
`US 2005.0218421A1
`
`(54) METHODS FOR PACKAGING A LIGHT
`EMITTING DEVICE AND PACKAGED
`LIGHT EMITTING DEVICES
`
`(76) Inventors: Peter Andrews, Durham, NC (US);
`Thomas G. Coleman, Pittsboro, NC
`(US); James Ibbetson, Goleta, CA
`(US); Michael Leung, Port Hueneme,
`CA (US); Gerald H. Negley, Carrboro,
`NC (US); Eric Tarsa, Goleta, CA (US)
`
`Correspondence Address:
`MYERS BIGELSIBLEY & SAJOVEC
`PO BOX 37428
`RALEIGH, NC 27627 (US)
`
`(21) Appl. No.:
`
`11/044,126
`
`(22) Filed:
`
`Jan. 27, 2005
`
`
`
`Related U.S. Application Data
`(60) Provisional application No. 60/557,924, filed on Mar.
`31, 2004.
`
`Publication Classification
`
`(51) Int. Cl. ................................................. H01L 29/22
`(52) U.S. Cl. .............................................................. 257/100
`
`ABSTRACT
`(57)
`Methods of packaging a Semiconductor light emitting device
`positioned in a reflective cavity are provided. A first quantity
`of encapsulant material is dispensed into the reflective cavity
`including the light emitting device therein and the first
`quantity of encapsulant in the reflective cavity is cured. A
`Second quantity of encapsulant material is dispensed onto
`the cured first quantity of encapsulant material. A lens is
`positioned in the reflective cavity on the dispensed Second
`quantity of encapsulant material. The dispensed Second
`quantity of encapsulant material is cured to attach the lens in
`the reflective cavity.
`
`1 O2
`
`Nichia Exhibit 1007
`Page 1
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`

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`Patent Application Publication Oct. 6, 2005 Sheet 1 of 10
`
`US 2005/0218421 A1
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`
`
`Nichia Exhibit 1007
`Page 2
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`

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`Patent Application Publication Oct. 6, 2005 Sheet 2 of 10
`
`US 2005/0218421 A1
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`
`
`200 N
`
`Nichia Exhibit 1007
`Page 3
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`

`

`Patent Application Publication Oct. 6, 2005 Sheet 3 of 10
`
`US 2005/0218421 A1
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`104 -
`
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`
`Nichia Exhibit 1007
`Page 4
`
`

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`
`Nichia Exhibit 1007
`Page 5
`
`
`
`
`

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`Patent Application Publication Oct. 6, 2005 Sheet 5 of 10
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`US 2005/0218421 A1
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`
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`Nichia Exhibit 1007
`Page 6
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`

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`Patent Application Publication Oct. 6, 2005 Sheet 6 of 10
`
`US 2005/0218421 A1
`
`
`
`
`
`
`
`
`
`
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`A.
`7% %
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`Y FIG. 9C
`
`Nichia Exhibit 1007
`Page 7
`
`

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`Patent Application Publication Oct. 6, 2005 Sheet 7 of 10
`
`US 2005/0218421 A1
`
`o
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`
`Nichia Exhibit 1007
`Page 8
`
`

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`Patent Application Publication Oct. 6, 2005 Sheet 8 of 10
`
`US 2005/0218421 A1
`
`
`
`
`
`
`
`
`
`y
`
`1100
`
`Mount light emitting /
`device
`
`1120
`Dispense First Quantity /
`of Encapsulant
`Material
`
`1130
`
`1140
`
`Dispense Second
`Quantity of
`Encapsulant Material
`
`
`
`
`
`
`
`Cure Dispensed
`Encapsulant Material
`
`End
`
`FG 11
`
`Nichia Exhibit 1007
`Page 9
`
`

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`Patent Application Publication Oct. 6, 2005 Sheet 9 of 10
`
`US 2005/0218421 A1
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`1200
`
`Mount light emitting /
`
`device
`
`1210
`
`Dispense Encapsulant
`Material to form
`Convex Meniscus
`
`V
`
`1220
`
`Cure Dispensed
`Encapsulant Material
`
`
`
`
`
`
`
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`
`
`
`FIG. 12
`
`Nichia Exhibit 1007
`Page 10
`
`

`

`Patent Application Publication Oct. 6, 2005 Sheet 10 of 10
`
`US 2005/0218421 A1
`
`13OO
`
`v
`Dispense First Quantity
`of Encapsulant
`Material to Form First
`Convex Meniscus
`
`1310
`Cure First Quantity of /
`Encapsulant Material
`
`
`
`Dispense Second
`Quantity of
`Encapsulant Material to
`Form Second Convex
`Meniscus
`
`1320
`
`1330
`
`
`
`
`
`
`
`
`
`Position Lens in
`Reflective Cavity
`
`/ 1340
`
`
`
`Cure Dispensed
`Second Quantity of
`Encapsulant Material
`
`End
`
`F.G. 13
`
`Nichia Exhibit 1007
`Page 11
`
`

`

`US 2005/0218421 A1
`
`Oct. 6, 2005
`
`METHODS FOR PACKAGING ALIGHT
`EMITTING DEVICE AND PACKAGED LIGHT
`EMITTING DEVICES
`
`RELATED APPLICATION
`0001. This application claims the benefit of and priority
`to U.S. Provisional Patent Application No. 60/557,924,
`entitled “Methods for Packaging a Light Emitting Device.”
`filed Mar. 31, 2004, the disclosure of which is hereby
`incorporated herein by reference as if Set forth in its entirety.
`
`BACKGROUND OF THE INVENTION
`0002 This invention relates to semiconductor light emit
`ting devices and fabricating methods therefore, and more
`particularly to packaging and packaging methods for Semi
`conductor light emitting devices.
`0003. It is known to provide semiconductor light emitting
`device type light Sources in packages that may provide
`protection, color Selection, focusing and the like for light
`emitted by the light emitting device. For example, the light
`emitting device may be a light emitting diode (“LED").
`Various problems may be encountered during packaging of
`a power LED for use as a light Source. Examples of Such
`possible problems will be described with reference to the
`cross-sectional illustrations of a power LED in FIGS. 1 and
`2. As shown in FIGS. 1 and 2, a power LED package 100
`generally includes a substrate member 102 on which a light
`emitting device 103 is mounted. The light emitting device
`103 may, for example, include an LED chip/submount
`assembly 103b mounted to the Substrate member 102 and an
`LED 103a positioned on the LED chip/submount assembly
`103b. The substrate member 102 may include traces or metal
`leads for connecting the package 100 to external circuitry.
`The substrate 102 may also act as a heatsink to conduct heat
`away from the LED 103 during operation.
`0004. A reflector, such as the reflector cup 104, may be
`mounted on the substrate 102 and surround the light emitting
`device 103. The reflector cup 104 illustrated in FIG. 1
`includes an angled or sloped lower sidewall 106 for reflect
`ing light generated by the LED 103 upwardly and away from
`the LED package 100. The illustrated reflector cup 104 also
`includes upwardly-extending walls 105 that may act as a
`channel for holding a lens 120 in the LED package 100 and
`a horizontal shoulder portion 108.
`0005. As illustrated in FIG. 1, after the light emitting
`device 103 is mounted on the substrate 102, an encapsulant
`material 112, Such as liquid Silicone gel, is dispensed into an
`interior reflective cavity 115 of the reflector cup 104. The
`interior reflective cavity 115 illustrated in FIG. 1 has a
`bottom surface defined by the substrate 102 to provide a
`closed cavity capable of retaining a liquid encapsulant
`material 112 therein. As further shown in FIG. 1, when the
`encapsulant material 112 is dispensed into the cavity 115, it
`may wick up the interior side of the sidewall 105 of the
`reflector cup 104, forming the illustrated concave meniscus.
`0006. As shown in FIG. 2, a lens 120 may then be placed
`into the reflective cavity 115 in contact with the encapsulant
`material 112. When the lens 120 is placed in the cavity 115,
`the liquid encapsulant material 112 may be displaced and
`move through the gap 117 between the lens 120 and the
`sidewall 105. The encapsulant may, thus, be moved out onto
`
`the upper surface of the lens 120 and/or upper surfaces of the
`sidewall 105 of the reflector cup 104. This movement, which
`may be referred to as Squeeze-Out, is generally undesirable
`for a number of reasons. In the depicted package arrange
`ment, the lens will sit on a lower shelf if the encapsulant is
`not cured in a domed meniscus shape prior to the lens attach
`Step. This may cause the lens to not float during thermal
`cycling and fail Via delamination of encapsulation to other
`Surfaces or via cohesive failure within the delamination,
`both of which may affect the light output. The encapsulant
`material or gel is generally Sticky and may interfere with
`automated processing tools used to manufacture the parts.
`Moreover, the gel may interfere with light output from the
`lens 120, for example, by changing the light distribution
`pattern and/or by blocking portions of the lens 120. The
`Sticky gel may also attract dust, dirt and/or other contami
`nants that could block or reduce light output from the LED
`package 100. The gel may also change the shape of the
`effective lens, which may modify the emitted light pattern/
`beam shape.
`0007. After placement of the lens 120, the package 100 is
`typically heat-cured, which causes the encapsulant material
`112 to solidify and adhere to the lens 120. The lens 120 may,
`thus, be held in place by the cured encapsulant material 112.
`However, encapsulant materials having a slight Shrinkage
`factor with curing, Such as a Silicone gel, generally tend to
`contract during the heat curing process. In addition, the
`coefficient of thermal expansion (CTE) effect generally
`causes higher floating of the lens at elevated temperatures.
`During cool-down, parts have a tendency to delaminate. AS
`the illustrated volume of encapsulant beneath the lens 120
`shown in FIG. 2 is relatively large, this contraction may
`cause the encapsulant material 112 to delaminate (pull away)
`from portions of the package 100, including the light emit
`ting device 103, a surface of the substrate 102, the sidewalls
`105 of the reflector cup 104 and/or the lens 120 during the
`curing process. The delamination may significantly affect
`optical performance, particularly when the delamination is
`from the die, where it may cause total internal reflection.
`This contraction may create gaps or voids 113 between the
`encapsulant material 112 and the light emitting device 103,
`lens 120, and/or reflector cup 104. Tri-axial stresses in the
`encapsulant material 112 may also cause cohesive tears 113'
`in the encapsulant material 112. These gaps 113 and/or tears
`113' may substantially reduce the amount of light emitted by
`the light emitting device package 100. The contraction may
`also pull out air pockets from crevices (i.e., reflector) or from
`under devices (i.e., die/Submount), which may then interfere
`with optical cavity performance.
`0008. During operation of the lamp, large amounts of
`heat may be generated by the light emitting device 103.
`Much of the heat may be dissipated by the substrate 102 and
`the reflector cup 104, each of which may act as a heatsink
`for the package 100. However, the temperature of the
`package 100 may still increase Significantly during opera
`tion. Encapsulant materials 112, Such as Silicone gels, typi
`cally have high coefficients of thermal expansion. As a
`result, when the package 100 heats up, the encapsulant
`material 112 may expand. As the lens 120 is mounted within
`a channel defined by the sidewalls 105 of the reflector cup
`104, the lens 120 may travel up and down within the
`sidewalls 105 as the encapsulant material 112 expands and
`contracts. Expansion of the encapsulant material 112 may
`extrude the encapsulant into Spaces or Out of the cavity Such
`
`Nichia Exhibit 1007
`Page 12
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`

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`US 2005/0218421 A1
`
`Oct. 6, 2005
`
`that, when cooled, it may not move back into the cavity. This
`could cause delamination, Voids, higher triaxial Stresses
`and/or the like, which may result in less robust light emitting
`devices. Such lens movement is further described, for
`example, in United States Patent Application Pub. No.
`2004/0041222. The sidewalls 105 may also help protect the
`lens 120 from mechanical shock and stress.
`
`SUMMARY OF THE INVENTION
`0009 Embodiments of the present invention provide
`methods of packaging a Semiconductor light emitting
`device, where the light emitting device may be mounted on
`a bottom Surface of a reflective cavity. A first quantity of
`encapsulant material is dispensed into the reflective cavity
`including the light emitting device and the first quantity of
`encapsulant in the reflective cavity is cured. A Second
`quantity of encapsulant material is dispensed onto the cured
`first quantity of encapsulant material. A lens is positioned in
`the reflective cavity on the dispensed Second quantity of
`encapsulant material. The dispensed Second quantity of
`encapsulant material is cured to attach the lens in the
`reflective cavity.
`0010. In other embodiments of the present invention,
`dispensing a first quantity of encapsulant material into the
`reflective cavity including the light emitting device includes
`dispensing a first portion of the first quantity of encapsulant
`material into the reflective cavity including the light emitting
`device and a second portion. The first portion is Sufficient to
`wet the light emitting device without filling the reflective
`cavity to a level exceeding the height of the light emitting
`device. The Second portion of the first quantity of encapsu
`lant material is dispensed onto the first portion of the first
`quantity of encapsulant material.
`0011. In further embodiments of the present invention,
`dispensing a first quantity of encapsulant material into the
`reflective cavity including the light emitting device includes
`dispensing a first portion of the first quantity of encapsulant
`material into the reflective cavity including the light emitting
`device and a second portion. The first portion of the first
`quantity is Sufficient to Substantially cover the light emitting
`device without forming any air pockets in the encapsulant
`material. The Second portion of the first quantity of encap
`Sulant material is dispensed onto the first portion of the first
`quantity of encapsulant material. The Second portion may be
`about twice the first portion. The Second quantity may be
`about equal to the first portion of the first quantity. The first
`portion may be sufficient to fill the reflective cavity to a
`height of about 250 microns.
`0012. In other embodiments of the present invention,
`curing the first quantity of encapsulant material includes
`curing the first portion of the first quantity of encapsulant
`material before dispensing the Second portion of the first
`quantity of encapsulant material. The first portion of the first
`quantity of encapsulant material may include a phosphor and
`the Second portion of the first quantity of encapsulant
`material may be Substantially free of phosphor.
`0013 In further embodiments of the present invention,
`the light emitting device is mounted at about a midpoint of
`the reflective cavity. The encapsulant material may be dis
`pensed at a point displaced from the midpoint towards a
`Sidewall of the cavity So that the encapsulant material is not
`dispensed directly onto the light emitting device. Alterna
`
`tively, the encapsulant material may be dispensed directly
`onto the light emitting device. Dispensing the encapsulant
`material may include forming a bead of the encapsulant
`material on an end of a dispenser and contacting the formed
`bead with the reflective cavity and/or the light emitting
`device to dispense the bead from the dispenser. The encap
`Sulant material may be a Silicone gel. The first quantity of
`encapsulant material may include a phosphor and the Second
`quantity of encapsulant material may be Substantially free of
`phosphor. In other words, each dispense may be of a material
`with or without phosphor.
`0014.
`In other embodiments of the present invention,
`positioning the lens includes advancing the lens into the
`reflective cavity until it contacts the cured first quantity of
`encapsulant material. A first quantity of encapsulant material
`may be dispensed that is Sufficient to establish a desired
`position for the lens in the reflective cavity. The light
`emitting device may be a light emitting diode (LED).
`0015. In further embodiments of the present invention,
`methods of packaging a Semiconductor light emitting device
`include providing the light emitting device on a bottom
`Surface of a reflective cavity. The light emitting device has
`a height relative to the bottom Surface. A first quantity of
`encapsulant material is dispensed into the reflective cavity
`including the light emitting device. The first quantity is
`sufficient to wet the light emitting device without filling the
`reflective cavity to a level exceeding the height of the light
`emitting device. A Second quantity of encapsulant material
`may be dispensed onto the first quantity of encapsulant
`material. The dispensed encapsulant material is cured.
`0016. In other embodiments of the present invention,
`packaging a Semiconductor light emitting device includes
`providing the light emitting device on a bottom Surface of a
`reflective cavity. A first quantity of encapsulant material is
`dispensed into the reflective cavity including the light emit
`ting device. The first quantity is Sufficient to Substantially
`cover the light emitting device without forming any air
`pockets in the encapsulant material. A Second quantity of
`encapsulant material may be dispensed onto the first quan
`tity of encapsulant material. The different dispenses may be
`of different materials having different viscosities or other
`properties. For example, different Viscosities of material
`may be Selected for wetting and/or meniscus formation
`purposes. The dispensed encapsulant material is cured.
`0017. In further embodiments of the present invention,
`packaging a Semiconductor light emitting device includes
`dispensing a first quantity of encapsulant material having a
`first index of refraction into a reflective cavity including the
`light emitting device. The first quantity of encapsulant
`material is cured. A Second quantity of encapsulant material
`is dispensed onto the cured first quantity of encapsulant
`material. The Second quantity of encapsulant material has a
`Second index of retraction, different from the first index of
`refraction. The first and Second index of refraction are
`selected to provide a buried lens in the reflective cavity. The
`Second quantity of encapsulant material is cured to form the
`buried lens.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0018 FIGS. 1 and 2 are cross-sectional side views
`illustrating a conventional light emitting device package;
`
`Nichia Exhibit 1007
`Page 13
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`

`

`US 2005/0218421 A1
`
`Oct. 6, 2005
`
`0019 FIGS. 3A to 3C are cross-sectional side views
`illustrating methods of packaging a light emitting device
`according to Some embodiments of the present invention;
`0020 FIG. 4A is a top view illustrating a light emitting
`device package Suitable for use with Some embodiments of
`the present invention;
`0021
`FIG. 4B is a cross-sectional side view illustrating
`the light emitting device package of FIG. 4A,
`0022 FIG. 5A is a top view illustrating a light emitting
`device package according to Some embodiments of the
`present invention;
`0023 FIG. 5B is a cross-sectional side view illustrating
`the light emitting device package of FIG. 5A;
`0024 FIG. 6 is a cross-sectional side view illustrating a
`light emitting device package according to further embodi
`ments of the present invention;
`0.025
`FIG. 7 is a cross-sectional side view illustrating a
`light emitting device package according to other embodi
`ments of the present invention;
`0026 FIGS. 8A to 8C are cross-sectional side views
`illustrating methods of packaging a light emitting device
`according to further embodiments of the present invention;
`0027 FIGS. 9A to 9C are cross-sectional side views
`illustrating methods of packaging a light emitting device
`according to other embodiments of the present invention;
`0028 FIGS. 10A to 10C are cross-sectional side views
`illustrating methods of packaging a light emitting device
`according to yet further embodiments of the present inven
`tion;
`0029 FIG. 11 is a flowchart illustrating operations for
`packaging a light emitting device according to Some
`embodiments of the present invention;
`0030 FIG. 12 is a flowchart illustrating operations for
`packaging a light emitting device according to Some other
`embodiments of the present invention; and
`0.031
`FIG. 13 is a flowchart illustrating operations for
`packaging a light emitting device according to yet further
`embodiments of the present invention.
`
`DETAILED DESCRIPTION
`0.032 The present invention now will be described more
`fully hereinafter with reference to the accompanying draw
`ings, in which embodiments of the invention are shown. This
`invention may, however, be embodied in many different
`forms and should not be construed as limited to the embodi
`ments Set forth herein. Rather, these embodiments are pro
`Vided So that this disclosure will be thorough and complete,
`and will fully convey the scope of the invention to those
`skilled in the art. In the drawings, the Size and relative sizes
`of layerS and regions may be exaggerated for clarity. Like
`numbers refer to like elements throughout.
`0033. It will be understood that when an element such as
`a layer, region or Substrate is referred to as being “on”
`another element, it can be directly on the other element or
`intervening elements may also be present. It will be under
`stood that if part of an element, Such as a Surface, is referred
`to as “inner, it is farther from the outside of the device than
`
`other parts of the element. Furthermore, relative terms Such
`as “beneath” or “overlies' may be used herein to describe a
`relationship of one layer or region to another layer or region
`relative to a Substrate or base layer as illustrated in the
`figures. It will be understood that these terms are intended to
`encompass different orientations of the device in addition to
`the orientation depicted in the figures. Finally, the term
`“directly’ means that there are no intervening elements. AS
`used herein, the term “and/or” includes any and all combi
`nations of one or more of the associated listed items.
`0034.
`It will be understood that, although the terms first,
`Second, etc. may be used herein to describe various ele
`ments, components, regions, layerS and/or Sections, these
`elements, components, regions, layerS and/or Sections
`should not be limited by these terms. These terms are only
`used to distinguish one element, component, region, layer or
`Section from another region, layer or Section. Thus, a first
`element, component, region, layer or Section discussed
`below could be termed a Second element, component,
`region, layer or Section without departing from the teachings
`of the present invention.
`0035 Various embodiments of the present invention for
`packaging a Semiconductor light emitting device 103 will be
`described herein. AS used herein, the term Semiconductor
`light emitting device 103 may include a light emitting diode,
`laser diode and/or other Semiconductor device which
`includes one or more Semiconductor layers, which may
`include Silicon, Silicon carbide, gallium nitride and/or other
`Semiconductor materials, a Substrate which may include
`Sapphire, Silicon, Silicon carbide and/or other microelec
`tronic Substrates, and one or more contact layers which may
`include metal and/or other conductive layers. In Some
`embodiments, ultraViolet, blue and/or green light emitting
`diodes (“LEDs) may be provided. Red and/or amber LEDs
`may also be provided. The design and fabrication of Semi
`conductor light emitting devices 103 are well known to
`those having skill in the art and need not be described in
`detail herein.
`0036 For example, the semiconductor light emitting
`device 103 may be gallium nitride-based LEDs or lasers
`fabricated on a Silicon carbide Substrate Such as those
`devices manufactured and Sold by Cree, Inc. of Durham,
`N.C. The present invention may be suitable for use with
`LEDs and/or lasers as described in U.S. Pat. Nos. 6,201,262;
`6,187,606; 6,120,600; 5,912,477; 5,739,554, 5,631,190;
`5,604,135; 5,523,589; 5,416,342; 5,393,993; 5,338,944;
`5,210,051; 5,027,168; 5,027,168; 4,966,862 and/or 4,918,
`497, the disclosures of which are incorporated herein by
`reference as if set forth fully herein. Other suitable LEDs
`and/or lasers are described in published U.S. Patent Publi
`cation No. U.S. 2003/0006418 A1 entitled Group III Nitride
`Based Light Emitting Diode Structures With a Quantum
`Well and Superlattice, Group III Nitride Based Quantum
`Well Structures and Group III Nitride Based Superlattice
`Structures, published Jan. 9, 2003, as well as published U.S.
`Patent Publication No. U.S. 2002/0123164A1 entitled Light
`Emitting Diodes Including Modifications for Light Extrac
`tion and Manufacturing Methods Therefor. Furthermore,
`phosphor coated LEDs, such as those described in U.S.
`application Ser. No. 10/659,241, entitled Phosphor-Coated
`Light Emitting Diodes Including Tapered Sidewalls and
`Fabrication Methods Therefor, filed Sep. 9, 2003, the dis
`closure of which is incorporated by reference herein as if Set
`
`Nichia Exhibit 1007
`Page 14
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`

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`US 2005/0218421 A1
`
`Oct. 6, 2005
`
`forth fully, may also be suitable for use in embodiments of
`the present invention. The LEDs and/or lasers may be
`configured to operate Such that light emission occurs
`through the Substrate. In Such embodiments, the Substrate
`may be patterned So as to enhance light output of the devices
`as is described, for example, in the above-cited U.S. Patent
`Publication No. U.S. 2002/O123164 A1.
`0037 Embodiments of the present invention will now be
`described with reference to the various embodiments illus
`trated in FIGS. 3-11. More particularly, some embodiments
`of a double-cure encapsulation process for use in packaging
`a light emitting device 103 are illustrated in FIGS. 3A
`through 3C. Such a double cure encapsulation proceSS may
`reduce problems associated with Shrinkage of encapsulant
`material during curing. AS will be described herein, for Some
`embodiments of the present invention, the double cure
`proceSS may include three dispense operations and two cure
`operations. However, it will be understood that more or less
`dispense operations and cure operations may also be used in
`packaging the light emitting device in other embodiments of
`the present invention. As will also be further described
`herein, embodiments of the present invention also include a
`multi-dispense operation, leading to a first cure operation
`followed by another Set of dispense and cure operations to
`attach a lens.
`0038. As illustrated in FIG. 3A, a first predetermined
`amount (quantity) of an encapsulant material, including two
`encapsulant material portions 112, 114 in the illustrated
`embodiments, is dispensed within the cavity 115. The encap
`Sulant material 112, 114 may be, for example, a liquid Silicon
`gel, an epoxy or the like. The first portion 112 may be
`dispensed to wet exposed Surface portions of the light
`emitting device 103, more particularly, the led chip/Sub
`mount assembly 101 of the light emitting device 103, and
`the substrate 102. Portions of the reflector cup 104 may also
`be wet by the initial dispense. In some embodiments of the
`present invention, the quantity of encapsulant material dis
`pensed as the first portion 112 is sufficient to wet the light
`emitting device 103 without filling the reflective cavity to a
`level exceeding the height of the light emitting device 103.
`In Some other embodiments of the present invention, the
`quantity of encapsulant material dispensed as the first por
`tion 112 is sufficient to substantially cover the light emitting
`device 103 without forming any air pockets in the encap
`Sulant material 112.
`0039. As shown in FIG. 3A, the light emitting device is
`positioned at about a midpoint 115m of the reflective cavity
`115. The encapsulant material may be dispensed from a
`dispenser 200 at a point 115d displaced from the midpoint
`115m towards a sidewall 105 of the reflective cavity 115 so
`that the encapsulant material 112 is not dispensed directly
`onto the light emitting device 103. Dispensing encapsulant
`material 112 directly on the light emitting device 103 may
`cause trapping of bubbles as the encapsulant material 112
`passes over the structure of the light emitting device 103
`from above. However, in other embodiments of the present
`invention, the encapsulant material 112 is dispensed on top
`of the light emitting device 103 die in addition to or instead
`of an offset dispense. Dispensing the encapsulant material
`112 may include forming a bead of the encapsulant material
`112 on an end of a dispenser 200 and contacting the formed
`bead with the reflective cavity 115 and/or the light emitting
`device 103 to dispense the bead from the dispenser.
`
`0040. The viscosity and/or other properties of the mate
`rial used for a dispense may be Selected Such that, for
`example, wetting occurs without bubble formation. In fur
`ther embodiments of the present invention, coatings may be
`applied to Surfaces contacted by the dispensed material to
`Speed/retard the wetting rate. For example, using certain
`known cleaning procedures that leave microscopic residue,
`Selected Surfaces may be treated and, thus, used to engineer
`the dynamics of the wetting action.
`0041. Due to the Surface properties of the inner surface of
`the reflector cup 104 defining the cavity 115, of the light
`emitting device 103 and of the encapsulant material 112,
`dispensed encapsulant material 112, even when dispensed
`from a point 115d displaced from the midpoint 115m of the
`cavity 115, may flow within the cavity 115 in a manner that
`could still cause bubbles in the encapsulant material 112. In
`particular, the encapsulant material 112 is expected to move
`or “wick' more rapidly around the inner surface of the
`reflector cup 104 and the sidewalls of the light emitting
`device 103 faster than over the top of the light emitting
`device 103. As a result, a bubble could be trapped on a side
`of the cavity 115 opposite from the side where the encap
`Sulant material is dispensed when the Side flowing encap
`Sulant material meets and then encapsulant material flows
`over the top of the light emitting device 103, thus being
`locally dispensed from above with no side outlet for air flow.
`Accordingly, the quantity of the first portion of dispensed
`encapsulant material 112 may be Selected to reduce or
`prevent the risk of forming Such bubbles. AS Such, as used
`herein, reference to “Substantially covering the light emit
`ting device 103 refers to covering enough of the structure of
`the light emitting device 103 so that such a bubble will not
`result when the remaining portion 114 of the first quantity of
`encapsulant material 112, 114 is dispensed.
`0042. After the initially dispensed encapsulant material
`112 is allowed to settle, the second portion 114 of the first
`predetermined quantity of encapsulant material is dispensed
`into the reflective cavity 115. The second portion 114 of the
`encapsulant material, in Some particular embodiments of the
`present invention, is about twice the first portion 112.
`0043. After dispensing all the first quantity of encapsu
`lant material 112, 114, the first quantity of the encapsulant
`material 112, 114 is cured, for example, by a heat treatment,
`to Solidify the encapsulant material 112, 114. After curing,
`the level of the encapsulant material 112, 114 within the
`reflective cavity 115 may drop from the level 114A to the
`level 114B as a result of shrinkage of the encapsulant
`material 112, 114.
`0044) In some embodiments of the present invention, the
`first portion 112 is cured before the second portion 114 is
`dispensed into the reflective cavity 115. For example, it is
`known to add a light converting material, Such as a phos
`phor, nano-crystals, or the like, to the encapsulant material
`112, 114 to affect the characteristics of the light emitted from
`the package 100. For purposes of the description herein,
`references will be made to a phosphor as a light converting
`material. However, it will be understood that other light
`converting materials may be used in place of phosphor.
`Depending on the desired color spectrum and/or color
`temperature tuning for the package 100, phosphor may be
`most beneficially utilized when positioned adjacent the
`emitter 103b, in other words, directly on top of the light
`
`Nichia Exhibit 1007
`Page 15
`
`

`

`US 2005/0218421 A1
`
`Oct. 6, 2005
`
`emitting device 103. As such, it may be desirable to include
`a phosphor in the Second portion 114 while not including a
`phosphor in the first portion 112. However, as the first
`portion 112 is below the second portion 114, phosphor may
`settle from the second portion 114 into the first portion 112,
`reducing the effectiveness of the phosphor addition in the
`Second portion 114. Accordingly, phosphor can be added to
`the first portion 112 to limit such settling and/or the first
`portion 112 can be cured before dispensing the Second
`portion 114.
`004.5 The use of multiple dispenses may also allow the
`addition of a