Patent Description:
Solid-state lighting devices such as light-emitting diodes (LEDs) are increasingly used in both consumer and commercial applications. Advancements in LED technology have resulted in highly efficient and mechanically robust light sources with a long service life. Accordingly, modern LEDs have enabled a variety of new display applications and are being increasingly utilized for general illumination and various other applications, often replacing incandescent and fluorescent light sources.

LEDs are solid-state devices that convert electrical energy to light and generally include one or more active layers of semiconductor material (or an active region) arranged between oppositely doped n-type and p-type layers. When a bias is applied across the doped layers, holes and electrons are injected into the one or more active layers where they recombine to generate emissions such as visible light or ultraviolet emissions. An LED chip typically includes an active region that may be fabricated, for example, from epitaxial layers of silicon carbide, gallium nitride, gallium phosphide, aluminum nitride, gallium arsenide-based materials, and/or from organic semiconductor materials. Photons generated by the active region are initiated in all directions.

Typically, it is desirable to operate LEDs at the highest light emission efficiency possible, which can be measured by the emission intensity in relation to the output power (e.g., in lumens per watt). A practical goal to enhance emission efficiency is to maximize extraction of light emitted by the active region in a direction of the desired transmission of light. In a typical LED package <NUM> illustrated in <FIG>, a single LED chip <NUM> is mounted on a reflective cup <NUM> by means of a solder bond or conductive epoxy. One or more wire bonds <NUM> can connect the ohmic contacts of the LED chip <NUM> to leads 18A and/or 18B, which may be attached to or integral with the reflective cup <NUM>. The reflective cup <NUM> may be filled with an encapsulant material <NUM>, which may contain a wavelength conversion material such as a phosphor. At least some light emitted by the LED chip <NUM> at a first wavelength spectrum may be absorbed by the phosphor, which may responsively emit light at a second wavelength spectrum. The entire assembly is then encapsulated in a clear protective resin <NUM>, which may be molded in the shape of a lens to direct the light emitted from the LED chip <NUM> in a direction <NUM> that is predominantly perpendicular to a surface of the reflective cup <NUM> where the LED chip <NUM> is mounted.

<FIG> shows another typical LED package <NUM> in which one or more LED chips <NUM> can be mounted onto a carrier such as a printed circuit board (PCB) carrier, substrate, or submount <NUM>. A metal reflector <NUM> mounted on the submount <NUM> surrounds the one or more LED chips <NUM> and reflects light emitted by the one or more LED chips <NUM> in a direction <NUM> predominantly perpendicular to a surface of the submount <NUM> on which the one or more LED chips <NUM> is mounted. One or more wire bond connections <NUM> are made between ohmic contacts on the one or more LED chips <NUM> and electrical traces 38A, 38B on the submount <NUM>. The mounted one or more LED chips <NUM> are then covered with an encapsulant <NUM>, which may provide environmental and mechanical protection to the LED chip(s) <NUM> while also acting as a lens.

<FIG> shows another typical LED package <NUM> in which an LED chip <NUM> can be mounted on a submount <NUM> with a hemispheric lens <NUM> formed over it. The LED chip <NUM> can be coated by a conversion material that can convert all or most of the light from the LED chip <NUM>. The hemispheric lens <NUM> is arranged to reduce total internal reflection of light. As a result, an increased amount of LED light that reaches the surface of the lens <NUM> transmits through the lens <NUM> on a first pass. Additionally, the lens <NUM> can be useful for directing light emission from the LED chip <NUM> in a desired emission pattern toward a direction <NUM> that is predominantly perpendicular to a surface of the submount <NUM> on which the LED chip <NUM> is mounted.

<FIG> shows another typical LED package <NUM> that is arranged to have primary light emission in a direction <NUM> that is predominantly parallel to a surface <NUM> on which the LED package <NUM> is mounted. The LED package <NUM> typically includes an LED chip <NUM> mounted on a submount <NUM>. In order to have the primary light emission in the direction <NUM>, the LED package <NUM> is mounted on its side in reference to the chip orientation, which is sometimes referred to as a sidelooker or side view LED. In this manner, the direction <NUM> is predominantly perpendicular to a surface of the submount <NUM> on which the LED chip <NUM> is mounted. In this regard, each of the LED packages <NUM>, <NUM>, <NUM>, and <NUM> of <FIG> has a predominant emission direction that is centered along or near the normal of the LED chip mounting surface as well as epitaxial layers within the LED chips.

<FIG> is a plot representing a typical spatial distribution for an emission pattern of a conventional LED package. The x-axis represents a viewing angle in degrees as measured from a direction normal to a primary emission face of an LED chip of the conventional LED package. For example, <NUM>° is perpendicular to the primary emission face. The y-axis represents relative luminous intensity for a given viewing angle. As illustrated, the highest luminous intensity percentages are centered along a direction that is predominantly perpendicular to the primary emission face of the LED chip, which is also predominantly perpendicular to the surface on which the LED chip is mounted. In this manner, the conventional LED packages as previously described, are all configured to have the primary emission faces of the LED chips oriented predominantly perpendicular to primary emission directions of the LED packages. <CIT> discloses a side-emitting light emitting device including a wavelength conversion element situated around the periphery of a non-wavelength converting lightguide that is situated above a light emitting surface. One or more specular and/or diffusing reflectors are used to direct the light in the lightguide toward the wavelength conversion element at the periphery. <CIT> discloses a method of manufacturing a light emitting module sequentially including: providing a light guiding plate having a first main surface being a light emitting surface, and a second main surface on the side opposite to the first main surface; providing a plurality of light emitting elements on the light guiding plate; and forming a wiring electrically connecting the plurality of light emitting elements. <CIT> discloses a semiconductor light emitting device including a semiconductor stacked layer having a light extraction surface perpendicular to a stacked surface of the semiconductor stacked layer, a light transmissive light guide member disposed on the semiconductor stacked layer, a light reflective member disposed on the light guide member, and a light reflective package which has an open portion corresponding to the light extraction surface and surrounds peripheral surfaces of the semiconductor stacked layer.

<CIT> discloses an LED package configured as a surface mount device.

The art continues to seek improved LEDs and solid-state lighting devices having reduced optical losses and providing desirable illumination characteristics capable of overcoming challenges associated with conventional lighting devices.

According to the present invention, there is provided a LED package according to claim <NUM>. In certain embodiments, the light-altering material may be arranged on or dispersed within the superstrate of the LED package. In certain embodiments, an overall thickness or height of the LED package may be less than or equal to <NUM>.

In certain embodiments, the light-altering material surrounds the first face, the second face, and at least one sidewall of the plurality of sidewalls of the LED package. In certain embodiments, the light-altering material may surround the first face, the second face, and at least three sidewalls of the plurality of sidewalls. Any material that is on the first face or on the second face may be devoid of a lumiphoric material. In certain embodiments, the light-altering material is continuous around the first face, the second face, and at least one sidewall. In certain embodiments, the light-altering material comprises a thinned light-altering material through which a portion of the one or more LED chips may be electrically connected. In certain embodiments, the LED package is configured to provide illumination to the edge of a light guide in a lighting fixture.

Embodiments of the disclosure are described herein with reference to cross-sectional view illustrations that are schematic illustrations of embodiments of the disclosure. As such, the actual thickness of the layers can be different, and variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are expected. For example, a region illustrated or described as square or rectangular can have rounded or curved features, and regions shown as straight lines may have some irregularity. Thus, the regions illustrated in the figures are schematic and their shapes are not intended to illustrate the precise shape of a region of a device and are not intended to limit the scope of the disclosure.

The present disclosure relates to solid-state lighting devices including light-emitting diodes (LEDs) and more particularly to LED packages. A light-altering material is provided within an LED package to redirect light toward a primary emission direction. The light-altering material is arranged on a first face, a second face, and possible on a plurality of sidewalls of a LED chip in the LED package. A lumiphoric material is arranged on one or more sidewalls of the plurality of sidewalls of the LED chip. A superstrate is arranged to mechanically support the LED chip from the first face. The light-altering material may be arranged on or dispersed within the superstrate. The primary emission direction of the LED package is substantially parallel to the first face or the second face of the LED chip in the LED package. In certain embodiments, an overall thickness or height of the LED package may be less than or equal to <NUM> (millimeters) mm. In other embodiments, an overall thickness or height of the LED package may be thicker than <NUM>. The term "superstrate" is used herein, in part, to avoid confusion with other substrates that may be part of the semiconductor light emitting device, such as a growth or carrier substrate of the LED chip or a submount of the LED package. The term "superstrate" is not intended to limit the orientation, location, and/or composition of the structure it describes.

An LED chip typically comprises an active LED structure or region that can have many different semiconductor layers arranged in different ways. The fabrication and operation of LEDs and their active structures are generally known in the art and are only briefly discussed herein. The layers of the active LED structure can be fabricated using known processes with a suitable process being fabrication using metal organic chemical vapor deposition. The layers of the active LED structure can comprise many different layers and generally comprise an active layer sandwiched between n-type and p-type oppositely doped epitaxial layers, all of which are formed successively on a growth substrate. It is understood that additional layers and elements can also be included in the active LED structure, including but not limited to, buffer layers; nucleation layers; super lattice structures; un-doped layers; cladding layers; contact layers; and current-spreading layers and light extraction layers and elements. The active layer can comprise a single quantum well, a multiple quantum well, a double heterostructure, or super lattice structures.

The active LED structure can be fabricated from different material systems, with some material systems being Group III nitride-based material systems. Group III nitrides refer to those semiconductor compounds formed between nitrogen and the elements in Group III of the periodic table, usually aluminum (Al), gallium (Ga), and indium (In). Gallium nitride (GaN) is a common binary compound. Group III nitrides also refer to ternary and quaternary compounds such as aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), and aluminum indium gallium nitride (AllnGaN). For Group III nitrides, silicon (Si) is a common n-type dopant and magnesium (Mg) is a common p-type dopant. Accordingly, the active layer, n-type layer, and p-type layer may include one or more layers of GaN, AlGaN, InGaN, and AllnGaN that are either undoped or doped with Si or Mg for a material system based on Group III nitrides. Other material systems include silicon carbide (SiC), organic semiconductor materials, and other Group III-V systems such as gallium phosphide (GaP), gallium arsenide (GaAs), and related compounds.

The active LED structure may be grown on a growth substrate that can include many materials, such as sapphire, silicon carbide, aluminum nitride (AIN), GaN, with a suitable substrate being a <NUM> polytype of SiC, although other SiC polytypes can also be used including 3C, <NUM>, and 15R polytypes. SiC has certain advantages, such as a closer crystal lattice match to Group III nitrides than other substrates and results in Group III nitride films of high quality. SiC also has a very high thermal conductivity so that the total output power of Group III nitride devices on SiC is not limited by the thermal dissipation of the substrate. Sapphire is another common substrate for Group III nitrides and also has certain advantages, including being lower cost, having established manufacturing processes, and having good light transmissive optical properties.

Different embodiments of the active LED structure can emit different wavelengths of light depending on the composition of the active layer and n-type and p-type layers. In some embodiments, the active LED structure emits blue light with a peak wavelength range of approximately <NUM> nanometers (nm) to <NUM>. In other embodiments, the active LED structure emits green light with a peak wavelength range of <NUM> to <NUM>. In other embodiments, the active LED structure emits red light with a peak wavelength range of <NUM> to <NUM>. The LED chip can also be covered with one or more lumiphoric or other conversion materials, such as phosphors, such that at least some of the light from the LED chip is absorbed by the one or more phosphors and is converted to one or more different wavelength spectra according to the characteristic emission from the one or more phosphors. In some embodiments, the combination of the LED chip and the one or more phosphors emits a generally white combination of light. The one or more phosphors may include yellow (e.g., YAG:Ce), green (e.g., LuAg:Ce), and red (e.g., Cai-x-ySrxEuyAlSiN<NUM>) emitting phosphors, and combinations thereof. Lumiphoric materials as described herein may be or include one or more of a phosphor, a scintillator, a lumiphoric ink, a quantum dot material, a day glow tape, and the like. Lumiphoric materials may be provided by any suitable means, for example, direct coating on one or more surfaces of an LED, dispersal in an encapsulant material configured to cover one or more LEDs, and/or coating on one or more optical or support elements (e.g., by powder coating, inkjet printing, or the like). In certain embodiments, lumiphoric materials may be downconverting or upconverting, and combinations of both downconverting and upconverting materials may be provided. In certain embodiments, multiple different (e.g., compositionally different) lumiphoric materials arranged to produce different peak wavelengths may be arranged to receive emissions from one or more LED chips.

Light emitted by the active layer or region of the LED chip typically has a lambertian emission pattern. For directional applications, internal mirrors or external reflective surfaces may be employed to redirect as much light as possible toward a desired emission direction. Internal mirrors may include single or multiple layers. Some multi-layer mirrors include a metal reflector layer and a dielectric reflector layer, wherein the dielectric reflector layer is arranged between the metal reflector layer and a plurality of semiconductor layers. A passivation layer is arranged between the metal reflector layer and first and second electrical contacts, wherein the first electrical contact is arranged in conductive electrical communication with a first semiconductor layer, and the second electrical contact is arranged in conductive electrical communication with a second semiconductor layer. For single or multi-layer mirrors including surfaces exhibiting less than <NUM>% reflectivity, some light may be absorbed by the mirror. Additionally, light that is redirected through the active LED structure may be absorbed by other layers or elements within the LED chip.

As used herein, a layer or region of a light-emitting device may be considered to be "transparent" when at least <NUM>% of emitted radiation that impinges on the layer or region emerges through the layer or region. Moreover, as used herein, a layer or region of an LED is considered to be "reflective" or embody a "mirror" or a "reflector" when at least <NUM>% of the emitted radiation that impinges on the layer or region is reflected. In some embodiments, the emitted radiation comprises visible light such as blue and/or green LEDs with or without lumiphoric materials. In other embodiments, the emitted radiation may comprise nonvisible light. For example, in the context of GaN-based blue and/or green LEDs, silver (for example, at least <NUM>% reflective) may be considered a reflective material. In the case of ultraviolet (UV) LEDs, appropriate materials may be selected to provide a desired, and in some embodiments high reflectivity; and/or a desired, and in some embodiments low, absorption. In certain embodiments, a "light-transmissive" material may be configured to transmit at least <NUM>% of emitted radiation of a desired wavelength.

The present invention is useful for LED chips having a lateral geometry. A lateral geometry LED chip typically includes both anode and cathode connections on the same side of the LED chip that is opposite a substrate, such as a growth substrate.

LED packages can be arranged in many different applications to provide illumination of objects, surfaces, or areas. In some applications, it is desirable for an LED package to provide such illumination while having dimensions as small as possible. An example of which is backlighting illumination for liquid crystal displays (LCD) including televisions, laptops, cell phones, and other handheld devices. In certain applications, the backlighting illumination is provided from one or more edges of an LCD display in the form of side-view or side-looker LED packages. As devices with LCD displays continue to become thinner, it is desirable for the corresponding LED packages to also be as thin as possible. While conventional side-view LED packages are continually made thinner than their predecessors, thickness restraints remain and manufacturing difficulties increase due to the configuration of how the LED chips are mounted within the side-view packages. As previously described, light from an active layer would typically have a lambertian emission profile. When the LED chip is mounted in a package, a face of the LED chip that is opposite the mounting surface is a primary emission face of the LED chip. A conventional side-view package typically has an LED chip mounted on a surface of the package such that a primary emission face of the LED chip is oriented predominantly perpendicular to a primary emission direction of the package. The package is then mounted on a side edge of the package in such a manner that the primary emission direction of the package is oriented toward the edge of an LCD display. The dimensions of side-view LED packages are typically measured as an overall length, width, and height of the package. The overall height of the package, which may also be referred to as an overall thickness of the package, is usually the smallest overall dimension. In an LCD application, a side-view package is typically arranged along an edge of the LCD display such that the smallest overall dimension of the package is aligned with the light guide of the display. When a typical side-view LED package is arranged to illuminate a display, the package is mounted on an edge such that a face of the LED chip inside the package directly faces the display. In this regard, conventional side-view LED packages are limited to thicknesses or heights of about <NUM> or above, with some examples as low as <NUM>. In certain embodiments as disclosed herein, an LED package is provided as a surface mount device having an overall thickness or height of less than or equal to <NUM>, or in a range from about <NUM> to about <NUM>, or in a range from about <NUM> to about <NUM>, or in a range from about <NUM> to about <NUM>.

<FIG> is an exploded cross-sectional view of an LED package <NUM> according to embodiments which are not part of the invention. The LED package <NUM> includes an LED chip <NUM> that comprises a first face <NUM>, a second face <NUM>, and a plurality of sidewalls <NUM>-<NUM>, <NUM>-<NUM> therebetween. While the LED chip <NUM> is illustrated in a cross-sectional view, it is understood the LED chip <NUM> includes other sidewalls. For example, a square or rectangular LED chip would include four sidewalls between the first face <NUM> and the second face <NUM>. In <FIG>, the LED chip <NUM> is illustrated as a lateral flip-chip LED where a chip anode pad 72a and chip cathode pad 72b are both located on the second face <NUM>. The LED chip <NUM> may comprise a vertical LED or a lateral LED that is not arranged in a flip-chip manner as previously described. The LED package <NUM> can include light-altering materials <NUM>-<NUM> to <NUM>-<NUM> that are configured to reflect, refract, or otherwise redirect light from the LED chip <NUM>. The light-altering materials <NUM>-<NUM> to <NUM>-<NUM> may be adapted for dispensing, depositing, or placing as a pre-formed component, and may include many different materials including light-reflective or refractive materials that reflect, refract, or otherwise redirect light. The light-altering materials <NUM>-<NUM> to <NUM>-<NUM> may include fused silica, fumed silica, and titanium dioxide (TiO<NUM>) particles suspended in a binder, such as silicone or epoxy. The light-altering materials <NUM>-<NUM> to <NUM>-<NUM> can include plastic, ceramic, or metal materials. In certain embodiments, the light-altering materials <NUM>-<NUM> to <NUM>-<NUM> may comprise a thickness sufficient to be mechanically stable, or the light-altering materials <NUM>-<NUM> to <NUM>-<NUM> may be deposited or coated on a support component. The light-altering materials <NUM>-<NUM> to <NUM>-<NUM> may comprise a white color to reflect and redirect light. In other embodiments, the light-altering materials <NUM>-<NUM> to <NUM>-<NUM> may comprise an opaque or black color, such as particles of carbon, silicon, or other materials for absorbing light. The LED package <NUM> further includes one or more optical materials <NUM>-<NUM> to <NUM>-<NUM> arranged proximate the LED chip <NUM>. The one or more optical materials <NUM>-<NUM> to <NUM>-<NUM> include lumiphoric materials possibly in combination with encapsulation materials, light diffusing or scattering materials, and light filtering materials. Additionally, die attach or bonding materials may be provided to mount the LED chip <NUM> within the LED package <NUM>. The LED package <NUM> may be configured with one or more additional materials <NUM> that may include further mechanical support, electrical traces, package bond pads, solder mask materials and combinations thereof. For examples where the additional materials <NUM> include electrical traces or other electrical connections, one or more electrically conductive paths <NUM> may be provided through the light-altering material <NUM>-<NUM> and the optical material <NUM>-<NUM>, if present. As previously described, the LED chip <NUM> may include a square or rectangular LED chip with four sidewalls between the first face <NUM> and the second face <NUM>. Accordingly, the light-altering material <NUM>-<NUM> to <NUM>-<NUM> may surround the first face <NUM>, the second face <NUM>, and three of the four sidewalls, while not surrounding one of the sidewalls (<NUM>-<NUM>) that is oriented closest to a primary emission direction of the LED package <NUM>. The one or more optical materials <NUM>-<NUM> to <NUM>-<NUM> may surround anywhere from one to all four sidewalls of the LED chip <NUM>.

<FIG> is an assembled cross-sectional view of the LED package <NUM> more generally described in <FIG>. In <FIG>, the LED chip <NUM> may be mounted in the LED package <NUM> on either the first face <NUM> or the second face <NUM>. The light-altering materials <NUM>-<NUM> to <NUM>-<NUM> may surround the first face <NUM>, the second face <NUM>, and at least one side wall <NUM>-<NUM> of the LED chip <NUM>. The one or more optical materials <NUM>-<NUM>, <NUM>-<NUM> may be provided around the LED chip <NUM> and between the light-altering materials <NUM>-<NUM> to <NUM>-<NUM>. The LED chip <NUM> may include four sidewalls and the light-altering materials <NUM>-<NUM> to <NUM>-<NUM> surround three of the four sidewalls. Notably, the light-altering materials <NUM>-<NUM> to <NUM>-<NUM> do not surround another sidewall <NUM>-<NUM> of the LED chip <NUM>. Accordingly, omnidirectional light that is emitted from the LED chip <NUM> may be reflected, refracted, or otherwise redirected by the light-altering materials <NUM>-<NUM> to <NUM>-<NUM> such that a primary emission direction <NUM> of the LED package <NUM> is substantially parallel to the first face <NUM> or the second face <NUM>. By keeping the first face <NUM> or the second face <NUM> substantially parallel to the primary emission direction <NUM>, an overall thickness T of the LED package <NUM> may be reduced compared with conventional side-view packages. For flip-chip configurations of the LED chip <NUM>, epitaxial layers of the LED chip <NUM> are closer or proximate to the second face <NUM>. The one or more optical materials <NUM>-<NUM>, <NUM>-<NUM> include a lumiphoric material that is configured to convert at least some of the light of the LED chip <NUM> to a different wavelength before exiting the LED package <NUM>. As illustrated in <FIG>, the one or more optical materials <NUM>-<NUM>, <NUM>-<NUM> may only be located adjacent to one or both of the sidewalls <NUM>-<NUM>, <NUM>-<NUM> of the LED chip <NUM>. In this manner, the LED chip <NUM> may be mechanically supported by the light-altering materials <NUM>-<NUM>, <NUM>-<NUM> or a component on which the light-altering materials <NUM>-<NUM>, <NUM>-<NUM> are formed, and any material that is on or directly on the first face <NUM> or on or directly on the second face <NUM> may be devoid of lumiphoric materials. The light-altering materials <NUM>-<NUM> to <NUM>-<NUM> may be continuous or an integral single component around the first face <NUM>, the second face <NUM>, and the at least one side wall <NUM>-<NUM>. In other embodiments, the light-altering materials <NUM>-<NUM> to <NUM>-<NUM> are formed in discontinuous segments and joined together in the LED package <NUM>. For example, the light-altering material <NUM>-<NUM> may be discontinuous with one or each of the light-altering materials <NUM>-<NUM>, <NUM>-<NUM>.

In certain embodiments, an LED package may include different arrangements of light-altering material. For example, an LED package includes
an LED chip comprising a first face, a second face, and a plurality of sidewalls therebetween, a first light-altering material substantially covering the first face, and a lumiphoric material arranged on a first sidewall of the plurality of sidewalls. A primary emission direction of the LED package is substantially parallel to the first face or the second face as previously described. The first light-altering material may be arranged in one or more layers on a superstrate
or dispersed within a superstrate that mechanically supports the LED chip. The superstrate may comprise a light-altering material as a dispersion of particles. A second light-altering material is arranged on the second face of the LED chip and a third light-altering material may extend between the first light-altering material and the second light-altering material. Each of the first, second, and third light-altering materials may include the same materials. In other embodiments, at least one of the first, second, and third light-altering materials may include a different type or amount of material than the other light-altering materials. In this regard, different areas of the LED package may be tailored to reflect, refract, or otherwise redirect light in differing amounts based on a particular application. In certain embodiments, at least one of the first, second, or third light-altering materials, or another optical material may comprise a thinned material through with a portion of the LED chip may be exposed or otherwise electrically connected.

<FIG> is a cross-sectional view of an LED package <NUM> according to embodiments disclosed herein. The LED package <NUM> includes an LED chip <NUM> that includes a first face <NUM>, a second face <NUM>, and a plurality of sidewalls <NUM>-<NUM>, <NUM>-<NUM> therebetween; a first light-altering material <NUM>; a second light-altering material <NUM>; and an optical material <NUM> including a lumiphoric material. The optical material <NUM> includes a lumiphoric material that is arranged on at least one of a first sidewall <NUM>-<NUM> and a second sidewall <NUM>-<NUM> of the LED chip <NUM>. As illustrated, the first light-altering material <NUM> substantially covers the first face <NUM>. In certain embodiments, at least a portion <NUM>' of the first light-altering material <NUM> may additionally extend along and be optionally spaced apart from at least the second sidewall <NUM>-<NUM>. A superstrate is configured to mechanically support the LED chip <NUM> from the first face <NUM>. Accordingly, the superstrate may comprise a material and/or a thickness that is sufficient to be mechanically stable as previously described. The first light-altering material <NUM> is deposited, coated, or otherwise arranged on a separate superstrate. The superstrate may comprise at least one of silicone, epoxy, plastic, ceramic, metal, sapphire, Si, or SiC, among others. As illustrated in <FIG>, the second light-altering material <NUM> is arranged on the second face <NUM> of the LED chip <NUM> and the portion <NUM>' of the first light-altering material <NUM> that extends toward the second light-altering material <NUM> along at least the second sidewall <NUM>-<NUM>. In certain embodiments, the first light-altering material <NUM> surrounds three sidewalls of the plurality of sidewalls <NUM>-<NUM>, <NUM>-<NUM> as previously described. The second light-altering material <NUM> may additionally extend on the optical material <NUM>. In this regard, the LED chip <NUM> may be surrounded by the first and second light-altering materials <NUM>, <NUM> everywhere except for the first sidewall <NUM>-<NUM>. Accordingly, light from the LED chip <NUM> as well as light converted by any lumiphoric material present in the optical material <NUM> have a primary emission direction <NUM> from the LED package <NUM> that is substantially parallel to the first face <NUM> or the second face <NUM>. As illustrated in <FIG>, the LED chip <NUM> further includes a chip anode pad <NUM> and a chip cathode pad <NUM>. For flip-chip embodiments, the chip anode pad <NUM> and the chip cathode pad <NUM> are formed on the second face <NUM> of the LED chip <NUM>. The LED package <NUM> further includes a package anode pad <NUM> and a package cathode pad <NUM> arranged to electrically connect with the LED chip <NUM> from the second face <NUM>. In particular, the package anode pad <NUM> and the package cathode pad <NUM> are electrically connected with the corresponding chip anode pad <NUM> and the chip cathode pad <NUM>. One or more electrically conductive paths <NUM> may be formed through the second light-altering material <NUM> to make these electrical connections. The electrically conductive paths <NUM> may include, but are not limited to, electrically conductive pedestals, bump bonds, solder material, wires, and vias. In certain embodiments, the second light-altering material <NUM> comprises a thinned light-altering material through which the electrically conductive paths <NUM> from the LED chip <NUM> are exposed. Additionally, the LED package <NUM> may include an insulating material <NUM> positioned between the package anode pad <NUM> and the package cathode pad <NUM> to provide electrical insulation when mounting the LED package <NUM>. The insulating material <NUM> may include a solder mask material as well as other dielectric materials.

As previously described, by positioning the first face <NUM> or the second face <NUM> substantially parallel to the primary emission direction <NUM> of the LED package <NUM>, the overall thickness T of the LED package <NUM> may be reduced compared with conventional side-view packages that turn the entire package including the LED chip inside on an edge. For the LED package <NUM>, a thickness t<NUM> of the first light-altering material <NUM> as measured from the first face <NUM> may include a range of about <NUM> microns (µm) to about <NUM> or more, or a range of about <NUM> to about <NUM>. In certain embodiments, the first light-altering material <NUM> may initially comprise a larger thickness (e.g. about <NUM>) and then the first light-altering material <NUM> may subsequently be thinned to a smaller thickness (e.g. about <NUM>). The LED chip <NUM> may comprise a thickness t<NUM> in a range of about <NUM> to about <NUM>, or in a range of about <NUM> to about <NUM>. For a thickness t<NUM> of about <NUM>, a growth substrate of the LED chip <NUM> may be removed. The second light-altering material <NUM> may comprise a total thickness t<NUM> as measured from the second face <NUM> in a range of about <NUM> to about <NUM>, or in a range of about <NUM> to about <NUM>, or in a range of about <NUM> to about <NUM>. The package anode pad <NUM> and the package cathode pad <NUM> may comprise a thickness t<NUM> in a range of about <NUM> to about <NUM>, or in a range of about <NUM> to about <NUM>, or in a range of about <NUM> to about <NUM>. In certain embodiments, an LED package may be configured with the thickness t<NUM> of about <NUM>, the thickness t<NUM> of about <NUM>, the thickness t<NUM> of about <NUM>, and the thickness t<NUM> of about <NUM> to provide an overall thickness of about <NUM>, or <NUM>. Accordingly, in certain embodiments as disclosed herein, the LED package <NUM> is provided as a surface mount LED package or device with an overall thickness of less than or equal to <NUM>, or in a range from about <NUM> to about <NUM>, or in a range from about <NUM> to about <NUM>, or in a range from about <NUM> to about <NUM>. In other embodiments, the LED package <NUM> may have an overall thickness of greater than <NUM>.

<FIG> is a cross-sectional view of the LED package <NUM> of <FIG> with an alternative configuration of the optical material <NUM>. In <FIG>, the optical material <NUM> is positioned between the first light-altering material <NUM> and the second light-altering material <NUM> in a similar manner as illustrated in <FIG>. In <FIG>, however, at least a portion of the optical material <NUM> is also positioned between the first light-altering material <NUM> and the first face <NUM> of the LED chip <NUM>. In this manner, light emitting from the LED chip <NUM> that passes through the first face <NUM> may interact with the optical material <NUM> before being reflected, refracted, or otherwise re-directed by the first light-altering material <NUM>. The optical material <NUM> includes a lumiphoric material and accordingly, at least a portion of light from the LED chip <NUM> that passes through the first face <NUM> may be converted to a different wavelength before exiting the package in the primary emission direction <NUM>.

LED packages according to embodiments disclosed herein may be manufactured in a variety of processing steps. In particular, a plurality of LED packages may be formed in bulk on a common superstrate before they are singulated into individual LED packages. For example, a plurality of LED chips may be mounted on a common superstrate that includes a first light-altering material. An optical material that include one or more lumiphoric materials, a second light-altering material, and electrical contacts for the plurality of LED packages may be subsequently formed on the common superstrate before individual LED packages are singulated. In this manner, different processing steps may be applied to a plurality of LED packages at the same time, thereby saving costs and reducing variation between individual LED packages.

<FIG> illustrate cross-sectional views at various steps of an exemplary manufacturing process according to embodiments disclosed herein. In <FIG>, a plurality of LED chips <NUM> are mounted on a superstrate <NUM>. In certain embodiments, the plurality of LED chips <NUM> may be mounted using a die attach adhesive, typically containing an epoxy or silicone. In this manner, each of the plurality of LED chips <NUM> is mechanically supported by the superstrate <NUM> at a first face <NUM> of each of the plurality of LED chips <NUM>. Additionally, each of the plurality of LED chips <NUM> includes a chip anode pad <NUM> and a chip cathode pad <NUM> on a second face <NUM> that is opposite the first face <NUM>. The superstrate <NUM> may include a plurality of superstrate portions <NUM>' that extend upward between the plurality of LED chips <NUM> and will serve as dividers for individual LED packages at later processing steps. As previously described, the superstrate <NUM> may comprise at least one of silicone, epoxy, plastic, ceramic, metal, sapphire, Si, or SiC, among others and a first light-altering material is bedeposited or coated on the superstrate <NUM>. The first light-altering material may include fused silica, fumed silica, or TiO<NUM>, other white particles, or even black particles suspended in a binder, such as silicone or epoxy.

In <FIG>, a dry film <NUM>, such as a photoresist, is applied to the second face <NUM> of each LED chip <NUM>. The dry film <NUM> is provided to substantially cover and protect each of the chip anode pads <NUM> and the chip cathode pads <NUM> during subsequent processing steps.

In <FIG>, an optical material <NUM> is dispensed or otherwise applied to the superstrate <NUM>. As previously described, the optical material <NUM> includes lumiphoric materials, possibly in combination with encapsulation materials, light diffusing or scattering materials, and light filtering materials. The optical material <NUM> includes one or more lumiphoric materials dispersed in a binder. As illustrated, the optical material <NUM> substantially covers each of the LED chips <NUM> and the superstrate <NUM>. The dry film <NUM> on each of the LED chips <NUM> serves to prevent the optical material <NUM> from contacting each of the chip anode pads <NUM> and the chip cathode pads <NUM>.

In <FIG>, a portion of the optical material <NUM> is removed to expose the dry film <NUM> on each of the LED chips <NUM>. Removing a portion of the optical material <NUM> may comprise one or more steps of planarization, grinding, polishing, or other material removal steps. In certain embodiments, the superstrate portions <NUM>' may also be exposed after removing a portion of the optical material <NUM>.

In <FIG>, the dry film <NUM> of <FIG> is removed to expose the chip anode pads <NUM> and the chip cathode pads <NUM> of each of the LED chips <NUM>. Subsequently, a plurality of electrically conductive paths <NUM> are formed on the chip anode pads <NUM> and the chip cathode pads <NUM>. As previously described, the electrically conductive paths <NUM> may include, but are not limited to, at least one of electrically conductive pedestals, bump bonds, solder material, wires, and vias.

In <FIG>, a second light-altering material <NUM> is deposited or dispensed over the superstrate <NUM>. As illustrated, the second light-altering material <NUM> substantially covers the optical material <NUM> as well as each of the LED chips <NUM>. Additionally, the second light-altering material <NUM> substantially covers the chip anode pads <NUM>, the chip cathode pads <NUM>, and the electrically conductive paths <NUM>. In this manner, at least a portion of the second light-altering material <NUM> is provided on the second face <NUM> of each LED chip <NUM> between and around where the chip anode pads <NUM> and the chip cathode pads <NUM> are located. Accordingly, light from a particular LED chip <NUM> may be reflected, refracted, or otherwise redirected by the second light-altering material <NUM> at the second face <NUM>. The second light-altering material <NUM> may include fused silica, fumed silica, or TiO<NUM>, other white particles, or even black particles suspended in a binder, such as silicone or epoxy as previously described.

In <FIG>, a portion of the second light-altering material <NUM> is removed to expose the electrically conductive paths <NUM> on each of the LED chips <NUM>. Removing a portion of the second light-altering material <NUM> may comprise one or more steps of planarization, grinding, polishing, thinning or other material removal steps. Notably, the second light-altering material <NUM> is thinned but not completely removed on the optical material <NUM>, thereby exposing a portion of each of the LED chips <NUM>, in this case the electrically conductive paths <NUM>. In this regard, the second light-altering material <NUM> covers the LED chips <NUM> and the optical material <NUM> while leaving a portion of each of the electrically conductive paths <NUM> exposed to facilitate electrical connection to the LED chips <NUM>.

In <FIG>, a package anode pad <NUM> and a package cathode pad <NUM> are formed over each of the LED chips <NUM> and the second light-altering material <NUM>. The package anode pad <NUM> and the package cathode pad <NUM> are arranged to electrically connect with the second face <NUM> of each of the LED chips <NUM>. In particular, each package anode pad <NUM> is electrically connected to each chip anode pad <NUM> and each package cathode pad <NUM> is electrically connected to each chip cathode pad <NUM> by way of the electrically conductive paths <NUM>. In certain embodiments, an insulating material <NUM> may be positioned between the package anode pad <NUM> and the package cathode pad <NUM> to provide electrical insulation. The insulating material <NUM> may include a solder mask material as well as other dielectric materials as previously described.

In <FIG>, individual LED packages <NUM>-<NUM>, <NUM>-<NUM> have been singulated and are ready to be surface mounted to a receiving substrate such as a printed circuit board (PCB). The singulation step may include sawing or dicing with a mechanical saw or a laser. In further embodiments, the singulation step may include forming dicing lines with a saw or laser, followed by applying a mechanical pressure to complete singulation. <FIG> illustrates an alternative configuration for the LED packages. In particular, the second light-altering material <NUM> of previous embodiments is positioned between the package anode pads <NUM> and the package cathode pads <NUM> and the optical material <NUM> to improve light reflection at the interface between the optical material <NUM> and the second light-altering material <NUM>, thereby improving brightness of the package. The second light-altering material <NUM> may be formed by stencil printing, screen printing, a photo process, or the like.

<FIG> is a cross-sectional view of an LED package <NUM> according to embodiments which are not part of the invention, where an LED chip <NUM> is mounted to a submount <NUM> from a second face <NUM> of the LED chip <NUM>. In this manner, the LED chip <NUM> is mechanically supported by the submount <NUM> from the second face <NUM>. The LED chip <NUM> further includes a first face <NUM> that is opposite the second face <NUM>. A first light-altering material <NUM> is provided on the first face <NUM> and may be formed with or without a superstrate as previously described. In this manner, the first light-altering material <NUM> may include fused silica, fumed silica, TiO<NUM>, other white particles, or black particles suspended in a binder, such as silicone or epoxy. An optical material <NUM> as previously described may be formed around the LED chip <NUM> on the submount <NUM>, and the first light-altering material <NUM> may be dispensed or otherwise deposited over the LED chip <NUM> and the optical material <NUM>. A second light-altering material <NUM> may surround one or more sidewalls of the LED chip <NUM> between the first light-altering material <NUM> and the submount <NUM>. The first light-altering material <NUM> comprises the same material or group of materials as the second light-altering material <NUM>. The first light altering material <NUM> and the second light-altering material <NUM> may be continuous or an integral single component with each other. The first light-altering material <NUM> comprises a different material or group of materials than the second light-altering material <NUM>. Suitable materials for the submount <NUM> include, but are not limited to ceramic materials such as aluminum oxide or alumina, AIN, or organic insulators like polyimide (PI) and polyphthalamide (PPA). The submount <NUM> can comprise a PCB, sapphire, Si or any other suitable material. For PCB embodiments different PCB types can be used such as standard FR-<NUM> PCB, metal core PCB, or any other type of PCB. The submount <NUM> includes a first submount surface <NUM> and a second submount surface <NUM> that is opposite the first submount surface <NUM>. A package anode pad <NUM> and a package cathode pad <NUM> are provided on the second submount surface <NUM> and are connected to corresponding electrical traces <NUM> on the first submount surface <NUM> by a plurality of vias <NUM> that extend through the submount <NUM>. The LED chip <NUM> is mounted to the electrical traces <NUM> in a manner such that a chip anode pad <NUM> is electrically connected to the package anode pad <NUM> and a chip cathode pad <NUM> is electrically connected to the package cathode pad <NUM>. A primary emission direction <NUM> of the LED package <NUM> is substantially parallel to the first face <NUM> or the second face <NUM> of the LED chip <NUM>.

<FIG> is a cross-sectional view of an LED package <NUM> according to embodiments disclosed herein where a first light-altering material <NUM> is formed on a superstrate <NUM>. An LED chip <NUM> is mechanically supported by the superstrate from a first face <NUM> of the LED chip <NUM>. A second face <NUM> of the LED chip <NUM>, which is opposite the first face <NUM>, comprises a chip anode pad <NUM>, a chip cathode pad <NUM>, and corresponding electrically conductive paths <NUM> as previously described. An optical material <NUM> surrounds the LED chip <NUM> and a second light-altering material <NUM> substantially covers the LED chip <NUM> and the optical material <NUM> in a manner similar to previous embodiments. A package anode pad <NUM>, a package cathode pad <NUM>, and an insulating material <NUM> as previously described complete the package. Notably, the first light-altering material <NUM> is positioned between the superstrate <NUM> and the LED chip <NUM>. Additionally, the first light-altering material <NUM> may be conformal to the superstrate <NUM> and a portion <NUM>' of the superstrate <NUM> that extends toward the second light-altering material <NUM>. In certain embodiments, the first light altering material <NUM> is arranged in one or more layers on the superstrate <NUM>. The one or more layers may comprise one or more materials including metal, oxide, ceramic, polymers, or combinations thereof.

<FIG> is a cross-sectional view of an LED package <NUM> according to certain embodiments which are not part of the invention. The LED package <NUM> includes n LED chip <NUM>, a first light-altering material <NUM>, a second light-altering material <NUM>, an optical material <NUM>, a chip anode pad <NUM>, a chip cathode pad <NUM>, electrically conductive paths <NUM>, a package anode pad <NUM>, a package cathode pad <NUM>, and an insulating material <NUM> as previously described. The optical material <NUM> includes a lumiphoric material that is arranged on a first sidewall <NUM> of the LED chip <NUM>. Notably, a second sidewall <NUM> of the LED chip <NUM> is positioned such that none of the optical material <NUM> is between the second sidewall <NUM> and the first light-altering material <NUM>. In this regard, light from the LED chip <NUM> is redirected by a portion of the first light-altering material <NUM> and a portion of the second light-altering material <NUM> before interacting with the optical material <NUM>. Three sidewalls of the LED chip <NUM> are configured so none of the optical material <NUM> is between the three sidewalls and the first light-altering material <NUM>.

<FIG> is a cross-sectional view of an LED package <NUM> according to certain embodiments which are not part of the invention. The LED package <NUM> includes an LED chip <NUM>, a first light-altering material <NUM>, a second light-altering material <NUM>, an optical material <NUM>, a chip anode pad <NUM>, a chip cathode pad <NUM>, electrically conductive paths <NUM>, a package anode pad <NUM>, a package cathode pad <NUM>, and an insulating material <NUM> as previously described. Notably, the first light-altering material <NUM> does not include a portion that extends toward the second light-altering material <NUM>. The first light-altering material <NUM> is planar. The LED chip <NUM> may be attached to the first light-altering material <NUM> and the optical material <NUM> is formed around the LED chip <NUM>. The second light-altering material <NUM> substantially covers the LED chip <NUM> and the optical material <NUM>. Additionally, a portion <NUM>' of the second light-altering material <NUM> extends toward the first light-altering material <NUM>. In this manner, the second light-altering material <NUM> may surround one or more sidewalls of the LED chip <NUM> as well as the optical material <NUM>.

<FIG> is a cross-sectional view of an LED package <NUM> according to certain embodiments which are not part of the invention. The LED package <NUM> includes a LED chip <NUM>, a first light-altering material <NUM>, a second light-altering material <NUM>, an optical material <NUM>, and a submount <NUM> as previously described. In a similar manner to the submount <NUM> of <FIG>, the LED chip <NUM> is mounted on a first submount surface <NUM>, and a package anode pad <NUM> and a package cathode pad <NUM> are provided on a second submount surface <NUM>. The package anode pad <NUM> and the package cathode pad <NUM> are electrically connected to corresponding electrical traces <NUM> on the first submount surface <NUM> by a plurality of vias <NUM>. In contrast to the LED chip <NUM> of <FIG>, the LED chip <NUM> is electrically connected to the electrical traces <NUM> by one or more wirebonds <NUM>. Notably, the one or more wirebonds <NUM> extend or loop into and are at least partially embedded in the first light-altering material <NUM> before connecting with the electrical traces <NUM>. In this manner, a portion of the one or more wirebonds <NUM> are concealed from paths of light from the LED chip <NUM> and accordingly, less light may be absorbed by the one or more wirebonds <NUM>. The one or more wirebonds <NUM> may only extend or loop through the optical material <NUM>.

In certain embodiments, various elements of the LED package, including but not limited to the superstrate, may include reinforcement materials such as one or more ceramics or fiberglass. As disclosed herein, LED packages may include other electrical components such as one or more electrostatic discharge (ESD) chips, and active or passive electrical components, and combinations thereof.

Claim 1:
A light emitting diode, LED, package (<NUM>) configured as a surface mount device, comprising:
one or more LED chips (<NUM>) comprising a first face (<NUM>), a second face (<NUM>) opposite the first face (<NUM>), and a plurality of sidewalls therebetween, wherein the one or more LED chips are mounted in the LED package on the first face (<NUM>) and a primary emission direction of the LED package is substantially parallel to the second face (<NUM>);
a superstrate (<NUM>) configured to mechanically support the one or more LED chips (<NUM>) from the first face (<NUM>);
a first light-altering material (<NUM>) on the first face and between the superstrate (<NUM>) and the one or more LED chips (<NUM>);
a second light-altering material (<NUM>) on the second face (<NUM>);
a lumiphoric material (<NUM>) on a first sidewall of the plurality of sidewalls, wherein the first light-altering material and the second light-altering material are configured to redirect light from the one or more LED chips toward the primary emission direction before the light interacts with the lumiphoric material; and
a package anode pad (<NUM>) and a package cathode pad (<NUM>) on the second light-altering material and arranged to electrically connect with the one or more LED chips from the second face, wherein a portion of the second light-altering material (<NUM>) is arranged between the one or more LED chips and the package anode pad and the package cathode pad.