Patent Publication Number: US-2023163155-A1

Title: Fan-out light-emitting diode (led) device substrate with embedded backplane, lighting system and method of manufacture

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a of U.S. patent application Ser. No. 16/831,378, filed Mar. 26, 2020, which claims the benefit of U.S. Provisional Application No. 62/826,612, filed on Mar. 29, 2019, which is incorporated by reference as if fully set forth. 
    
    
     BACKGROUND 
     Precision control lighting applications may require production and manufacturing of small light-emitting diode (LED) lighting systems. The smaller size of such systems may require unconventional components and manufacturing processes. 
     SUMMARY 
     Panels of LED arrays and LED lighting systems are described. A panel includes a substrate having a top and a bottom surface. Multiple backplanes are embedded in the substrate, each having a top and a bottom surface. Multiple first electrically conductive structures extend at least from the top surface of each of the backplanes to the top surface of the substrate. Each of multiple LED arrays is electrically coupled to at least some of the first conductive structures. Multiple second conductive structures extend from each of the backplanes to at least the bottom surface of the substrate. At least some of the second electrically conductive structures are coupled to at least some of the first electrically conductive structures via the backplane. A thermal conductive structure is in contact with the bottom surface of each of the backplanes and extends to at least the bottom surface of the substrate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more detailed understanding can be had from the following description, given by way of example in conjunction with the accompanying drawing wherein: 
         FIG.  1    is a top view of an example LED array; 
         FIG.  2    is a cross-sectional view of an example panel including multiple LED arrays; 
         FIG.  3    is a cross-sectional view of an example LED lighting system including a singulated LED array assembly coupled to a circuit board; 
         FIG.  4    is a block diagram of an example circuit board to which an LED lighting system may be attached; 
         FIG.  5    is a block diagram of an example wireless device in which an LED lighting system may be incorporated; 
         FIG.  6    is a back view of an example wireless device; 
         FIG.  7    is a flow diagram of an example method of manufacturing an LED lighting system, such as the LED lighting system of  FIG.  2   ; and 
         FIGS.  8 A,  8 B,  8 C,  8 D,  8 E,  8 F,  8 G,  8 H,  8 I,  8 J and  8 K  are cross sectional views of the LED lighting system at various stages in the manufacturing process. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Examples of different light illumination systems and/or light emitting diode (“LED”) implementations will be described more fully hereinafter with reference to the accompanying drawings. These examples are not mutually exclusive, and features found in one example may be combined with features found in one or more other examples to achieve additional implementations. Accordingly, it will be understood that the examples shown in the accompanying drawings are provided for illustrative purposes only and they are not intended to limit the disclosure in any way. Like numbers refer to like elements throughout. 
     It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms may be used to distinguish one element from another. For example, a first element may be termed a second element and a second element may be termed a first element without departing from the scope of the present invention. As used herein, the term “and/or” may include any and all combinations of one or more of the associated listed items. 
     It will be understood that when an element such as a layer, region, or substrate is referred to as being “on” or extending “onto” another element, it may be directly on or extend directly onto the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or extending “directly onto” another element, there may be no intervening elements present. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it may be directly connected or coupled to the other element and/or connected or coupled to the other element via one or more intervening elements. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present between the element and the other element. It will be understood that these terms are intended to encompass different orientations of the element in addition to any orientation depicted in the figures. 
     Relative terms such as “below,” “above,” “upper,”, “lower,” “horizontal” or “vertical” may be used herein to describe a relationship of one element, layer, or region to another element, layer, or region 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. 
     Further, whether the LEDs, LED arrays, electrical components and/or electronic components are housed on one, two or more electronics boards may also depend on design constraints and/or application. 
     Semiconductor light emitting devices (LEDs) or optical power emitting devices, such as devices that emit ultraviolet (UV) or infrared (IR) optical power, are among the most efficient light sources currently available. These devices (hereinafter “LEDs”), may include light emitting diodes, resonant cavity light emitting diodes, vertical cavity laser diodes, edge emitting lasers, or the like. Due to their compact size and lower power requirements, for example, LEDs may be attractive candidates for many different applications. For example, they may be used as light sources (e.g., flash lights and camera flashes) for hand-held battery-powered devices, such as cameras and cell phones. They may also be used, for example, for automotive lighting, heads up display (HUD) lighting, horticultural lighting, street lighting, torch for video, general illumination (e.g., home, shop, office and studio lighting, theater/stage lighting and architectural lighting), augmented reality (AR) lighting, virtual reality (VR) lighting, as back lights for displays, and IR spectroscopy. A single LED may provide light that is less bright than an incandescent light source, and, therefore, multi-junction devices or arrays of LEDs (such as monolithic LED arrays, micro LED arrays, etc.) may be used for applications where more brightness is desired or required. 
       FIG.  1    is a top view of an example LED array  102 . In the example illustrated in  FIG.  1   , the LED array  102  is an array of emitters  120 . LED arrays may be used for any application, such as those requiring precision control of LED array emitters. Emitters  120  in the LED array  102  may be individually addressable or may be addressable in groups/subsets. 
     An exploded view of a 3×3 portion of the LED array  102  is also shown in  FIG.  1   . As shown in the 3×3 portion exploded view, the LED array  102  may include emitters  120  that each have a width w 1 . In embodiments, the width w 1  may be approximately 100 μm or less (e.g., 30 μm). Lanes  122  between the emitters  120  may be a width, w 2 , wide. In embodiments, the width w 2  may be approximately 20 μm or less (e.g., 5 μm). The lanes  122  may provide an air gap between adjacent emitters or may contain other material. A distance di from the center of one emitter  120  to the center of an adjacent emitter  120  may be approximately 120 μm or less (e.g., 30 μm). It will be understood that the widths and distances provided herein are examples only and that actual widths and/or dimensions may vary. 
     It will be understood that, although rectangular emitters arranged in a symmetric matrix are shown in  FIG.  1   , emitters of any shape and arrangement may be applied to the embodiments described herein. For example, the LED array  102  of  FIG.  1    may include over 20,000 emitters in any applicable arrangement, such as a 20×100 matrix, a symmetric matrix, a non-symmetric matrix, or the like. It will also be understood that multiple sets of emitters, matrixes, and/or boards may be arranged in any format to implement the embodiments described herein. 
     As mentioned above, LED arrays, such as the LED array  102 , may include emitters that have fine pitch and line spacing. An LED array such as this may be referred to as a micro LED array or simply a micro LED. A micro LED may include an array of individual emitters provided on a substrate or may be a single silicon wafer or die divided into segments that form the emitters. The latter type of micro LED may be referred to as a monolithic LED. Such arrays may pose challenges for making reliable interconnections between individual LEDs or emitters and a circuit board and/or other components in an LED lighting system, particularly where each LED or emitter is separately addressable. Additionally, such arrays may require significant power to power them, such as 60 watts or more, and, therefore, may emit significant heat during operation. Accordingly, for such arrays, a structure is needed that can accommodate the fine line space and individual addressability of the finely spaced emitters and provide sufficient heat dissipation. 
     Embodiments described herein may provide for LED lighting systems, panels including a plurality of LED arrays and methods of manufacture for LED arrays with a fine line space and may provide sufficient heat dissipation to meet the requirements of such an LED array. Such LED arrays and LED lighting systems may be used in various applications, including, for example, camera flash applications. 
       FIG.  2    is a cross-sectional view of an example panel  200  including multiple LED arrays. In the example illustrated in  FIG.  2   , the panel  200  includes a substrate  212  and two LED array assemblies  202  and  204 . The substrate  212  may have a top surface  210  and a bottom surface  214  and may be formed from any suitable circuit board material, such as an organic material. In embodiments, the substrate  212  may be formed from a number of different materials, such as a core material, laminate materials, dielectrics, solder masks and conductive materials. Each of the two LED array assemblies  202  and  204  may include a backplane  220  embedded in the substrate  212 , multiple first conductive structures  226 , multiple second conductive structures  228 ,  229 , a thermal conductor  230 , an LED array  240 , an underfill material  244  and wavelength converting structure  242 . The backplane  220  may have a top surface  222  and a bottom surface  224 . The LED array  240  may be a micro LED, such as described above with respect to  FIG.  1   . 
     In embodiments, for each of the LED array assemblies  202  and  204 , the first conductive structures  226  extend from the top surface of the backplane  220  through the substrate  212  and extend above the top surface  210  of the substrate  212 . In some embodiments, the first conductive structures  226  may not extend above the top surface  210  of the substrate  212  but may stop at or below the top surface  210  of the substrate  212 . In some embodiments, the first conductive structures  226  may include a combination of different conductive structures. For example, the first conductive structures  226  may include conductive vias that extend between the backplane  220  and the top surface  210  of the substrate  212 . Conductive pillars may be disposed on and electrically coupled to the conductive vias (e.g., via metal pads on top of the conductive vias). Solder bumps may be formed on the pillars, which may be reflowed and each coupled to an LED or emitter in an LED array. In some embodiments, a subset of the first conductive structures  216  may be electrically coupled to the LED array. While two first conductive structures  226  are shown coupled to each backplane  220  in  FIG.  2   , an array of first conductive structures  226  may be coupled to each backplane  220  and may have similar line spacing to the corresponding LED array  224 . 
     Although not shown in  FIG.  2   , each of the LED arrays  240  may be electrically coupled to corresponding second conductive structures  228 ,  229 , such as by electrical connections between the first conductive structures  226  and the second conductive structures  228 ,  229  via surface traces, vias or other metallization in or on the backplane  220  as will be understood to one of ordinary skill in the art. This may enable individual LEDs or emitters in the LED arrays  240  to be individually driven by a driver and/or other circuitry when the panel  200  is diced into individual LED array assemblies  202  and  204  and mounted on a circuit board or otherwise electrically coupled to another external assembly. In embodiments, the backplane  220  may be an interposer substrate, which may be formed from a non-organic material. In embodiments, the backplane  220  may be fully embedded in the substrate  212  such that the substrate  212  completely surrounds the backplane  220  on all sides. The backplane  220  may be formed from any of a number of different materials, including, for example organic, inorganic, silicon or glass materials. 
     In the example shown in  FIG.  2   , the second electrical conductors  228 ,  229  provide an electrical connection between the top surface  222  of the backplane  220  and the bottom surface  214  of the substrate  210 . The electrically conductive structures  228  may, for example, be conductive vias in the substrate  210 . In some embodiments, the electrically conductive structures  228  may be microvias, wires, metal pillars, solder columns, or other electrically conductive structures. The electrically conductive structures  229  may, for example, be electrical traces that extend horizontally from the backplane  220  to the electrically conductive structures  228  and provide an electrical connection therebetween. As will be understood, various types and arrangements of electrical traces may be used, including, for example, fan-in, fan-out, linear and curved horizontal layouts. The electrically conductive structures  228 ,  229  may be formed from a variety of electrically conductive materials, including, for example, metals, such as copper, silver, aluminum, gold, or metal alloys, or conductive polymeric compositions, graphene, or conductive ceramics. 
     The thermal conductor  230  may be a structure of any type of thermal material with good heat transfer properties, such as copper, aluminum, or other metal material. The thermal conductor  230  may be a metal slug or other rigid heat transfer plate. The thermal conductor  230  may be disposed in a cavity in the bottom surface  214  of the substrate  210  and be thermally coupled to the backplane  220 . In the example illustrated in  FIG.  2   , the thermal conductor  230  has a top surface in contact with the backplane  220  and a bottom surface that is co-planar with the bottom surface  214  of the substrate  212 . In embodiments, however, the bottom surface of the thermal conductor  230  may be substantially co-planar, recessed with respect to the bottom surface  214  of the substrate  212  or extend below the bottom surface  214  of the substrate  212 . When the panel  200  is diced, and an individual LED array assembly  202  or  204  is mounted on a circuit board, the thermal conductor  230  may be coupled to a corresponding thermal plate or other heat sink device or material, which may provide for the amount of heat dissipation needed for an LED array, such as described above with respect to  FIG.  1   . 
     A wavelength converting structure  242  may be disposed over each of the LED arrays  240 . In embodiments, the wavelength converting structure  242  may be a phosphor material, such as a molded or ceramic material containing at least one phosphor material or quantum dots or dyes. The wavelength converting structure  242  may be any suitable thickness to provide desired wavelength converting properties using a selected wavelength converting material. An LED array, combined with one or more wavelength converting materials, may create white light or monochromatic light of other colors when in an ON state. All, or only a portion of, light emitted by the LED in the ON state may be converted by the wavelength converting structure  242 . Unconverted light may be part of the final spectrum of light emitted from the LED array assembly  202 ,  204 , though it need not be. By way of example, an LED array assembly  202 ,  204  with a wavelength converting structure  242  may be or include blue-emitting LEDs or emitters combined with a yellow-emitting phosphor material or green-emitting and red-emitting phosphor materials. By way of another example, the LED array assembly  202 ,  204  with a wavelength converting structure  242  may be or include UV-emitting LEDs or emitters combined with blue-emitting and yellow-emitting phosphor materials or blue-emitting, green-emitting and red-emitting phosphor materials. 
     The underfill material  244  may provide protection for otherwise exposed electrical and/or electronic components and conductive elements and/or provide or assist with mechanical coupling of the LED array  244  to the top surface  210  of the substrate  212 . In embodiments, the underfill material may be a polymeric binder and may surround portions of the first conductive structures  226  that project above the top surface  212  of the substrate  210 . 
     LED array assemblies, such as the LED array assembly  202 ,  204  of  FIG.  2    may include additional elements (not shown), such as light absorbers, reflectors, other optical coatings, or electrically insulating material. In embodiments, an LED array assembly may include an optically and electrically insulating material, such as organic, inorganic or a combination organic/inorganic binder or filler material. For example, adhesives, epoxies, acrylate or nitrocellulose may be used in conjunction with ceramic particles to provide the underfill  244 . Another organic/inorganic binder, filler or sidewall may be, for example, an epoxy with embedded reflective titanium oxide or other reflective scattering particles. Inorganic binders may include sol-gel (e.g., a sol-gel of TEOS or MTMS) or liquid glass (e.g., sodium silicate or potassium silicate), also known as water glass. In embodiments, binders may include fillers that adjust physical properties. Fillers may include inorganic nanoparticles, silica, glass particles or fibers or other materials capable of improving optical or thermal performance. 
     In embodiments, microlenses or other primary or secondary optical elements, such as reflectors, scattering elements or absorbers, may be coupled or positioned with respect to each LED or emitter or associated wavelength converting structure. Additionally or alternatively, a primary optic may be positioned over the entire LED array, which may be directly attached or mounted at a distance from the LED array in suitable packaging. Protective layers, transparent layers, thermal layers or other packaging structures may be used, as needed, for specific applications. 
       FIG.  3    is a cross-sectional view of an example LED lighting system including a singulated LED array assembly  202  coupled to a circuit board  300 . In the example illustrated in  FIG.  3   , the bottom surface  214  of the substrate  212  is placed adjacent a top surface of the circuit board  300 . The circuit board may have a number of conductive pads  302 . In the example illustrated in  FIG.  3   , the conductive pads  302  on the circuit board  300  are soldered or otherwise electrically coupled to the second conductive structures  229 . The thermally conductive structure  230  in the substrate  212  may also be soldered, placed in contact with or otherwise thermally coupled to a thermally conductive pad  304  on the circuit board. The direct contact and/or bond between the thermally conductive structure  230  and the circuit board  300  enables efficient heat transfer from the LED assembly  202  to the circuit board  300  for heat sinking purposes without need for additional heat dissipating structures over the top of the LED lighting system (or elsewhere) that may, for example, otherwise block light emission from the LED array  240 . The circuit board  300  may be part of a larger system used in specific applications (examples are described below with respect to  FIGS.  4 ,  5  and  6   ). Since the second conductive structures  229  are electrically coupled with the first conductive structures  226 , the LED array  202  may be electrically coupled to the circuit board  300  for powering, driving or otherwise controlling optical emission from the LED array  202  via circuitry on the circuit board  300 . 
     As mentioned above, LED arrays, such as the LED arrays  202 ,  204 , may be addressable assemblies and may support applications that benefit from fine-grained intensity, spatial, and temporal control of light distribution. This may include, but not be limited to, precise spatial patterning of emitted light from pixel blocks or individual pixels. Depending on the application, emitted light may be spectrally distinct, adaptive over time, and/or environmentally responsive. The LED arrays may provide pre-programmed light distribution in various intensity, spatial or temporal patterns. The emitted light may be based at least in part on received sensor data and may be used for optical wireless communications. Associated optics may be distinct in a pixel, pixel block, or device level. An example LED array may include a device having a commonly controlled central block of high density pixels with an associated common optic, whereas edge pixels may have individual optics. Common applications supported by LED arrays may include camera flashes, automotive headlights, architectural and area illumination, street lighting, and informational displays. 
       FIG.  4    is a top view of an example circuit board  300  that includes an LED device attachment region  418  for attachment of an LED array assembly, such as LED array assemblies  202 ,  204 . In the example illustrated in  FIG.  4   , the circuit board  300  includes a power module  412 , a sensor module  414 , and a connectivity and control module  418  on a substrate. 
     The sensor module  414  may include sensors needed for an application in which the LED array is to be implemented. Example sensors may include optical sensors (e.g., IR sensors and image sensors), motion sensors, thermal sensors, mechanical sensors, proximity sensors, or even timers. By way of example, LEDs in street lighting, general illumination, and horticultural lighting applications may be turned off/on and/or adjusted based on a number of different sensor inputs, such as a detected presence of a user, detected ambient lighting conditions, detected weather conditions, or based on time of day/night. This may include, for example, adjusting the intensity of light output, the shape of light output, the color of light output, and/or turning the lights on or off to conserve energy. For ARNR applications, motion sensors may be used to detect user movement. The motion sensors themselves may be LEDs, such as IR detector LEDs. By way of another example, for camera flash applications, image and/or other optical sensors or pixels may be used to measure lighting for a scene to be captured so that the flash lighting color, intensity illumination pattern, and/or shape may be optimally calibrated. In alternative embodiments, the circuit board  300  does not include a sensor module. 
     The connectivity and control module  416  may include the system microcontroller and any type of wired or wireless module configured to receive a control input from an external device. By way of example, a wireless module may include blue tooth, Zigbee, Z-wave, mesh, WiFi, near field communication (NFC) and/or peer to peer modules. The microcontroller may be any type of special purpose computer or processor that may be embedded in an LED lighting system and configured or configurable to receive inputs from the wired or wireless module or other modules, devices or systems in the LED lighting system (such as sensor data and data fed back from an LED array attached at the LED device attach region  418 ) and provide control signals to other modules based thereon. Algorithms implemented by the special purpose processor may be implemented in a computer program, software, or firmware incorporated in a non-transitory computer-readable storage medium for execution by the special purpose processor. Examples of non-transitory computer-readable storage mediums include a read only memory (ROM), a random access memory (RAM), a register, cache memory, and semiconductor memory devices. The memory may be included as part of the microcontroller or may be implemented elsewhere, either on or off the circuit board  300 . 
     The term module, as used herein, may refer to electrical and/or electronic components disposed on individual circuit boards that may be soldered to one or more circuit boards  300 . The term module may, however, also refer to electrical and/or electronic components that provide similar functionality, but which may be individually soldered to one or more circuit boards in a same region or in different regions. While the circuit board  300  is illustrated in  FIG.  4    as having certain modules, these are for illustration and example only. One of ordinary skill in the art will recognize that a circuit board may include any number and variety of different modules depending on the application. 
     As mentioned above, an LED lighting system, such as illustrated in  FIG.  3   , may be used in a number of different applications, and may be particularly useful in flash applications where closely packed LED arrays and/or individually addressable LED devices or emitters may be desirable.  FIGS.  5  and  6    are diagrams of example application systems that may incorporate LED lighting systems, such as the LED lighting system  300  of  FIG.  3   . The examples illustrated in  FIGS.  5  and  6    are for an LED flash application, although one of ordinary skill in the art will understand that LED array assemblies, such as described herein, may be used for many different applications. 
     An LED array may be well suited for camera flash applications for mobile devices. Typically, an intense brief flash of light from a high intensity LED may be used to support image capture. Unfortunately, with conventional LED flashes, much of the light is wasted on illumination of areas that are already well lit or that do not otherwise need to be illuminated. Use of a light emitting pixel array may provide controlled illumination of portions of a scene for a determined amount of time. This may allow the camera flash to, for example, illuminate only those areas imaged during rolling shutter capture, provide even lighting that minimizes signal to noise ratios across a captured image and minimizes shadows on or across a person or target subject, and/or provide high contrast lighting that accentuates shadows. If emitters of the LED array are spectrally distinct, color temperature of the flash lighting may be dynamically adjusted to provide wanted color tones or warmth. 
       FIG.  5    is a diagram of an example wireless device  500 . In the example illustrated in  FIG.  5   , the wireless device  500  includes a processor  512 , a transceiver  502 , an antenna  504 , a speaker/microphone  506 , a keypad  508 , a display/touchpad  510 , a memory  516 , a power source  518 , and a camera  514 . 
     The processor  512  may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a microprocessor, one or more microprocessors in association with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, an integrated circuit (IC), a state machine, and the like. The processor  512  may be coupled to, and may receive user input data from, the speaker/microphone  506 , the keypad  508 , the display/touchpad  510  and/or the camera  514 . The processor  512  may also output user data to the speaker/microphone  506 , the keypad  508 , the display/touchpad  510  and/or the camera  514 . In addition, the processor  512  may access information from, and store data in, any type of suitable memory, such as the memory  516 . The processor  512  may receive power from the power source  518  and may be configured to distribute and/or control the power to the other components in the wireless device  500 . 
     The processor  512  may also be coupled to the camera  514 . In embodiments, the camera  514  may include, for example, an image sensor, read out circuitry, a flash module and/or any other required circuitry or controls required to operate the camera  514 . In embodiments, the flash module may include an LED lighting system, such as the LED lighting system  300  of  FIG.  3   , and a driver, one or more sensors and/or any other circuitry or controls required to operate the flash. 
       FIG.  6    is a back view of a wireless device  600  showing more detail of the camera  514 . In the example illustrated in  FIG.  6   , the wireless device  600  includes a casing  620  and a camera  514 . The camera  514  includes a lens  640  via which the camera&#39;s image sensor (not shown in  FIG.  6   ) may capture an image of a scene. The camera module  514  may also include a flash  650  that may include one or more LED arrays, which may be a part of one or more LED lighting systems, such the LED lighting system  300  of  FIG.  3   . 
       FIG.  7    is a flow diagram of an example method  700  of manufacturing a panel of LED arrays and/or an LED lighting system, such as the panel  200  of  FIG.  2    and/or the LED lighting system  300  of  FIG.  3   .  FIGS.  8 A,  8 B,  8 C,  8 D,  8 E,  8 F,  8 G,  8 H,  8 I,  8 J and  8 K  are cross sectional views of a panel of LED arrays at various stages in the manufacturing method. 
     In the example method  700  illustrated in  FIG.  7   , a cavity is formed in a substrate ( 702 ).  FIG.  8 A  is a cross-sectional view  800 A of the substrate  802 . The substrate  802  has vias  803  formed therein and metallization  804  formed over portions of the top and bottom surfaces of the substrate  802  and in the vias  803 . The metallization  804  form at least portions of the second conductive structures  228 ,  229  of  FIG.  2   .  FIG.  8 B  is a cross-sectional view  800 B of the substrate  802  with a cavity  806  formed therein. While the opening is shown in the cross-sectional view as completely separating the substrate  806  into two pieces, the cavity may be formed partially through the substrate or may be a via or other opening formed completely through the substrate but surrounded on all sides by at least a portion of the substrate  802 . 
     Referring back to  FIG.  7   , a backplane may be placed in the cavity in the substrate ( 704 ).  FIGS.  8 C and  8 D  are cross-sectional views  800 C and  800 D of the substrate at different points in the placing of the backplane. In  FIG.  8 C , a tape  808  or other temporary structure is placed over the substrate  802  and adhered or otherwise coupled to a top surface  810  of the metallization  804 . In  FIG.  8 D , a backplane  812  is placed in the cavity  806  and adhered or otherwise coupled to the tape or other temporary structure  808 . 
     Referring back to  FIG.  7   , at least one layer of a dielectric material may be formed over the substrate and the backplane ( 706 ).  FIGS.  8 E and  8 F  are cross-sectional views  800 E and  800 F of the substrate at various points during the formation of the at least one layer of the dielectric material.  FIG.  8 E  is a cross-sectional view showing dielectric material  814  formed over one side of the backplane  812  and the substrate  802  while the other side of the backplane  812  and the substrate  802  are still on the tape or other temporary structure  808 . In the example illustrated in  FIG.  8 E , the dielectric material  814  also fills all voids and vias within the substrate  802  that are not filled with another material. In  FIG.  8 F , the tape or other temporary structure  808  is removed, and at least one other layer of the dielectric material  814  is formed on the side of the substrate  802  and the backplane  812  exposed by the removal of the tape of other temporary structure  808 . In embodiments, the dielectric material may be a polymer dielectric material, such as polyimide. 
     The at least one layer of dielectric material  814  may be one or more redistribution layers (RDL). The number of RDL layers may depend on the specific application for which the LED array panel is being implemented. Relative to the panel  200  of  FIG.  2   , the substrate  802 , along with at least portions of the dielectric material  814 , may form the substrate  212  of  FIG.  2    in which the backplane  220  is embedded. In other words, one method of embedding the backplane  220  in the substrate  212  may include forming a cavity in a substrate, such as the substrate  802 , and then forming one or more layers of dielectric over the substrate and the backplane such that the backplane is embedded in the substrate along with the at least one layer of dielectric material. 
     Referring back to  FIG.  7   , a cavity may be formed in the at least one layer of dielectric material, exposing at least a portion of a surface of the backplane ( 708 ). A heat conductive material is placed in the at least one layer of dielectric material ( 710 ). Referring back to  FIG.  8 F , a cavity is formed in the dielectric material  814 , and the heat conductive material  818  is placed in the cavity. 
       FIG.  8 G  is a cross-sectional view  800 G of the panel. In  FIG.  8 G , the entire assembly of  FIG.  8 F  has been flipped, and vias have been formed in what is now the top surface of the dielectric material  814  and exposing a surface of the backplane  812 . The vias may be filled or lined with a conductive material, and conductive pads  816  may be formed on an outer surface of the dielectric material  814 . The vias (and optionally the pads) with the conductive material may form the first conductive structures  226  of  FIG.  2   , for example. Other vias and optionally conductive pads  816  may be formed in what is now the bottom surface of the dielectric material  814 . These may be electrically coupled to the metallization  804  and may be part of the second conductive structures  228 ,  229  of  FIG.  2   , which extend to the bottom surface of the substrate  212 . Although not shown in  FIG.  8 G , these portions of the vias/pads  816  formed in the bottom surface of the dielectric material  814  and the metallization  804  may be electrically coupled to the vias/pads  816  formed in the top surface of the dielectric material  814  by traces and/or vias in or on the backplane  812  or by other portions of the metallization  804  or conductive materials lining or filling the vias, as explained above with respect to  FIG.  2   . This may provide an electrical coupling between the first conductive structures  226  and the second conductive structures  228 ,  229 , as described above. While only three vias/pads  816  are shown extending from the top surface of the backplane  812  in  FIG.  8 G , there may be an array of closely spaced vias/pads, which may be electrically coupled to individual LED or emitters in the LED array. 
       FIGS.  8 H,  8 I,  8 J, and  8 K  are diagrams of examples  800 H,  800 I,  800 J and  800 K of the panel at various additional stages in the method. In  FIG.  8 H , a solder mask or other passivation material  820  may be formed on certain portions of top and bottom surfaces of the dielectric material  814 . In  FIG.  8 I , conductive pillars  822 , such as copper pillars, may be formed on the conductive pads  816  of  FIG.  8 G . In  FIG.  8 J , solder material  824 , such a solder bumps or balls, may be formed on the conductive pillars  822 . In  FIG.  8 K , an LED array  826  may be placed or otherwise disposed over the solder material  822 . The entire assembly  800 K may be heated, and the solder material  822  may reflow, thus electrically and mechanically coupling the LED array  826  to the pillars  822 . The pillars  822  may be coupled to individual LEDs or emitters in the LED array  826 . Although not shown, subsequent processing steps may be performed, including forming the underfill, forming the wavelength converting structure over the LED array  826  (e.g., phosphor integration), substrate thinning or laser liftoff (e.g., thinning or removal of any growth or other temporary substrate of the LED array  826 ) and/or dicing the panel into multiple LED lighting systems, such as the LED lighting system  300  of  FIG.  3   . 
     In embodiments, the wavelength converting structure may be formed by electrophoretically depositing a material containing at least one phosphor material with application of a voltage. Varying an applied voltage duration may correspondingly vary an amount and thickness of the deposited material. Alternatively, the LED may be coated with the phosphor-containing material, for example using an organic binder to adhere phosphor particles to the LED array. Phosphor-containing materials may be dispensed, screen printed, sprayed, molded or laminated. Alternatively, for certain applications. Glass containing at least one phosphor material and/or a pre-formed sintered ceramic containing a phosphor material may be coupled to the LED array. 
     While the Figures described above show the thermally conductive material, the LED array and the backplane having certain relative sizes, one of ordinary skill in the art will recognize that the sizes of these elements may vary. For example, the backplane may be larger or smaller than the corresponding LED array, and the thermally conductive material may be larger or smaller than the backplane. The sizes of each of these elements may depend, for example, on performance and cost optimization. 
     Having described the embodiments in detail, those skilled in the art will appreciate that, given the present description, modifications may be made to the embodiments described herein without departing from the spirit of the inventive concept. Therefore, it is not intended that the scope of the invention be limited to the specific embodiments illustrated and described.