Patent Publication Number: US-2023148008-A1

Title: Light-emitting device with metal inlay and top contacts

Description:
CROSS REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of U.S. patent application Ser. No. 16/934,917, filed Jul. 21, 2020, which is incorporated by reference as if fully set forth. 
    
    
     BACKGROUND 
     Precision control lighting applications may require production and manufacturing of small addressable light-emitting diode (LED) lighting systems. The smaller size of such systems may require unconventional components and manufacturing processes. 
     SUMMARY 
     Light-emitting devices are described herein. A device includes a hybridized device having a top surface and a bottom surface and a packaging substrate comprising a metal inlay in an opening on a top surface of the packaging substrate. The metal inlay is thermally coupled to the bottom surface of the hybridized device. The device also includes conductive contacts on the top surface of the packaging substrate and conductive connectors electrically coupled between the top surface of the hybridized device and the top surface of the packaging 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 drawings wherein: 
         FIG.  1    is a top view of an example LED array; 
         FIG.  2 A  is a cross-sectional view of an example hybridized device; 
         FIG.  2 B  is a cross-sectional view of an example LED lighting system incorporating the example hybridized device of  FIG.  2 A ; 
         FIG.  3 A  is a cross-sectional view of an example application system that incorporates the LED lighting system of  FIG.  2 B ; 
         FIG.  3 B  is a cross-sectional view of another example application system that incorporates the LED lighting system of  FIG.  2 B ; 
         FIG.  4 A  is a top view of the example LED lighting system of  FIG.  2 B ; 
         FIG.  4 B  is a top view of the example application systems of  FIGS.  3 A and  3 B ; 
         FIG.  5    is a diagram of an example vehicle headlamp system that may incorporate the LED lighting system of  FIG.  2 B ; 
         FIG.  6    is a diagram of another example vehicle headlamp system; and 
         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 B . 
     
    
    
     DETAILED DESCRIPTION 
     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. 
     LEDs may be arranged into arrays for some applications. For example, LED arrays may support applications that benefit from fine-grained intensity, spatial, and temporal control of light distribution. This may include, but is not 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. 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 electronics and optics may be distinct at an emitter, emitter block or device level. 
     LED arrays may be formed from one, two or three dimensional arrays of LEDs, VCSELs, OLEDs, or other controllable light emitting systems. LED arrays may be formed as emitter arrays on a monolithic substrate, formed by partial or complete segmentation of a substrate, formed using photolithographic, additive, or subtractive processing, or formed through assembly using pick and place or other suitable mechanical placement. LED arrays may be uniformly laid out in a grid pattern, or, alternatively, may be positioned to define geometric structures, curves, random, or irregular layouts. 
       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 . 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., 40 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). In some embodiments, the width w 2  may be as small as 1 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., 45 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 200×100 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 applicable format to implement the embodiments described herein. 
     As mentioned above, LED arrays, such as the LED array  102 , may include up to 20,000 or more emitters. Such arrays may have a surface area of 90 mm 2  or greater and may require significant power to power them, such as 60 watts or more. An LED array such as this may be referred to as a micro LED array or simply a micro LED. In some embodiments, micro LEDs may include hundreds, thousands or even millions of LEDs or emitters positioned together on centimeter scale area substrates or smaller. A micro LED may include an array of individual emitters provided on a substrate or may be a single silicon wafer or die partially or fully divided into segments that form the emitters. 
     A controller may be coupled to selectively power subgroups of emitters in an LED array to provide different light beam patterns. At least some of the emitters in the LED array may be individually controlled through connected electrical traces. In other embodiments, groups or subgroups of emitters may be controlled together. In some embodiments, the emitters may have distinct non-white colors. For example, at least four of the emitters may be RGBY groupings of emitters. 
     LED array luminaires may include light fixtures, which may be programmed to project different lighting patterns based on selective emitter activation and intensity control. Such luminaires may deliver multiple controllable beam patterns from a single lighting device using no moving parts. Typically, this is done by adjusting the brightness of individual LEDs in a 1D or 2D array. Optics, whether shared or individual, may optionally direct the light onto specific target areas. In some embodiments, the height of the LEDs, their supporting substrate and electrical traces, and associated micro-optics may be less than 5 millimeters. 
     LED arrays, including LED or μLED arrays, may be used to selectively and adaptively illuminate buildings or areas for improved visual display or to reduce lighting costs. In addition, such LED arrays may be used to project media facades for decorative motion or video effects. In conjunction with tracking sensors and/or cameras, selective illumination of areas around pedestrians may be possible. Spectrally distinct emitters may be used to adjust the color temperature of lighting, as well as support wavelength specific horticultural illumination. 
     Street lighting is an important application that may greatly benefit from use of LED arrays. A single type of LED array may be used to mimic various street light types, allowing, for example, switching between a Type I linear street light and a Type IV semicircular street light by appropriate activation or deactivation of selected emitters. In addition, street lighting costs may be lowered by adjusting light beam intensity or distribution according to environmental conditions or time of use. For example, light intensity and area of distribution may be reduced when pedestrians are not present. If emitters are spectrally distinct, the color temperature of the light may be adjusted according to respective daylight, twilight, or night conditions. 
     LED arrays are also well suited for supporting applications requiring direct or projected displays. For example, warning, emergency, or informational signs may all be displayed or projected using LED arrays. This allows, for example, color changing or flashing exit signs to be projected. If an LED array includes a large number of emitters, textual or numerical information may be presented. Directional arrows or similar indicators may also be provided. 
     Vehicle headlamps are an LED array application that may require a large number of pixels and a high data refresh rate. Automotive headlights that actively illuminate only selected sections of a roadway may be used to reduce problems associated with glare or dazzling of oncoming drivers. Using infrared cameras as sensors, LED arrays may activate only those emitters needed to illuminate the roadway while deactivating emitters that may dazzle pedestrians or drivers of oncoming vehicles. In addition, off-road pedestrians, animals, or signs may be selectively illuminated to improve driver environmental awareness. If emitters are spectrally distinct, the color temperature of the light may be adjusted according to respective daylight, twilight, or night conditions. Some emitters may be used for optical wireless vehicle to vehicle communication. 
     To individually drive or control the individual LEDs or emitters in the array, a silicon backplane may be provided in close proximity to the LED array. In some embodiments, the silicon backplane may include circuitry to receive power from one or more sources to power various portions of the silicon backplane, circuitry to receive image input from one or more sources for displaying an image via the LED array, circuitry for communications between the silicon backplane and external controllers (e.g., vehicle headlamp controls, general lighting controls, etc.), circuitry for generating a signal, such as a pulse width modulated (PWM) signal, for controlling operation of the individual LEDs or emitters in the array based on, for example, received image input and communications received from external sources and a number of LED drivers for individually driving the LEDs or emitters in the array based on the generated signal. In embodiments, the silicon backplane may be a complementary metal-oxide-semiconductor (CMOS) backplane, which may include the same number of drivers as LEDs or emitters in a corresponding LED array. In some embodiments, the silicon backplane may be an application specific integrated circuit (ASIC). In some embodiments, one driver may be provided for each group of some number of LEDs or emitters and control may be of groups of LEDs or emitters rather than individual. Each driver may be electrically coupled individually to the corresponding LED or emitter or groups of LEDs or emitters. While the silicon backplane is described above with respect to particular circuitry, one of ordinary skill in the art will understand that a silicon backplane used for driving an LED array, such as described herein, may include more, less or different components that potentially carry out different functions without departing from the embodiments described herein. 
     As mentioned above, the individual drivers in the silicon backplane may be electrically coupled to individual LEDs or emitters or groups of LEDs or emitters in the LED array. As such, the LED array must be placed in close proximity to the silicon backplane. In embodiments, this may be accomplished by individually coupling copper pillar bumps or other connectors in an array of copper pillar bumps or connectors on a surface of the LED array to corresponding connectors on an opposing surface of the silicon backplane. A silicon backplane, such as described above, may become extremely hot during operation, particularly given its close proximity to the LED array. Accordingly, heat dissipation can be challenging for such devices. While some solutions are known for heat dissipation for semiconductor devices, such solutions often include structures that dissipate heat through the top of the device. Due to light-emission from the LED arrays, however, heat dissipation through the top of the device may not be practical or possible. Embodiments described herein provide for structures that may enable effective and efficient heat dissipation through the bottom surface of the device. 
     Additionally, an LED array, such as the LED array  102 , and the associated silicon backplane, may require a number of passive elements, such as resistors, capacitors, and crystals, to be placed on a circuit board in close proximity to the silicon backplane. In addition to providing heat dissipation through the bottom surface of the device, embodiments described herein may also provide for an LED package that enables placement of a large number of passive components (e.g., 27 or more) on a top surface of the circuit board and in close proximity to the backplane and LED array. Further, embodiments described herein may provide for a low profile LED array package that may accommodate one or more passive elements and enable dissipation of heat generated by the silicon backplane and the LED array. 
       FIG.  2 A  is a cross-sectional view of an example hybridized device  200 . In the example illustrated in  FIG.  2 A , the hybridized device  200  includes a silicon backplane  204 . A first surface  203  of an LED array  202 , such as a μLED, may be mounted on a first surface  205  of the silicon backplane  204 . The first surface  205  of the silicon backplane  204  may also be referred to herein as a top surface, and the first surface  203  of the LED array  202  may also be referred to herein as a bottom surface, for simplicity of description. However, one of ordinary skill in the art will understand that the first surface  205  may be a bottom surface if the hybridized device  200  is turned upside down, a side surface if the hybridized device  200  is turned sideways, etc. Similarly, the first surface  203  may be become a top surface if the hybridized device is turned upside down, a side surface if the hybridized device is  200  is turned sideways, etc. As mentioned above, an array of connectors (not shown) on the first surface  205  of the silicon backplane  204  may be soldered, reflowed or otherwise electrically and mechanically coupled to an array of connectors on the bottom surface of the LED array  202 . The array of connectors may be any array of connectors, such as an array of copper pillar bumps. The LED array  202  may have a depth D 1 . In embodiments, the depth D 1  may be, for example, between 5 and 250 μm. The silicon backplane  204  may have a depth D 2 . In embodiments, the depth D 2  may be, for example, between 100 μm and 1 mm. The hybridized device  200  may also be referred to as a hybridized die. 
       FIG.  2 B  is a cross-sectional view of an example LED lighting system  250  incorporating the example hybridized device  200  of  FIG.  2 A . In the example illustrated in  FIG.  2 B , the hybridized device  200  is packaged in a packaging substrate  208 . 
     In the example illustrated in  FIG.  2 B , a second surface  207  of the silicon backplane  204  is mounted on a first surface  209  of a metal inlay  210 . The second surface  207  of the silicon backplane  204  may also be referred to herein as a bottom surface, and the first surface  209  of the metal inlay  210  may also be referred to herein as a top surface. However, one of ordinary skill in the art will understand that the second surface  207  may be a top surface if the hybridized device  200  is turned upside down, a side surface if the hybridized device  200  is turned sideways, etc. Similarly, the first surface  209  may be become a bottom surface if the hybridized device is turned upside down, a side surface if the hybridized device is  200  is turned sideways, etc. In the example illustrated in  FIG.  2 B , the second surface  207  of the silicon backplane  204  and the first surface  209  of the metal inlay  210  are joined by a metal layer  206 . The metal layer  206  may be any metal with good thermal properties that enables heat transfer between the silicon backplane  204  and the metal inlay  210 . In embodiments, the metal layer  206  may be silver. The metal layer  206  thermally couples the silicon backplane  204  to the metal inlay  210 . 
     The metal inlay  210  may be any one piece or multiple layers of one or more types of metal with good thermal properties. In embodiments, the metal inlay  210  is a single piece of metal, such as copper or aluminum member or body. The metal inlay  210  may have a second surface  211  that may contact another circuit board, heat sink or other metal inlay or piece of metal, examples of which are described below, to facilitate heat transfer from the LED array  202  and the silicon backplane  204  to the circuit board, heat sink or other inlay or piece of metal via the metal inlay  210 . The second surface  211  of the metal inlay  210  may also be referred to herein as a bottom surface. However, one of ordinary skill in the art will understand that the second surface  211  may be a top surface if the hybridized device  200  is turned upside side, a side surface if the hybridized device  200  is turned sideways, etc. The metal inlay  210  may also include side surfaces. Depending on the shape, the metal inlay  210  may have any number of side surfaces or a single side surface, which may be a top surface, bottom surface, etc. depending on orientation of the hybridized device  200 . While not shown in  FIG.  2 B , one or more of a conductive pad may be a part of or coupled to the first and/or second surface  209 / 211  of the metal inlay  210  and may cover part of the first and/or second surface  209 / 211 , all of the first and/or second surface  209 / 211  or extend beyond the first and/or second surface  209 / 211 . 
     In the illustrated embodiment, the metal inlay  210  is embedded in the substrate  208  such that the metal layer  206 , the silicon backplane  204  and the LED array  202  protrude and extend above a first surface  213  of the substrate  208 . The first surface  213  may also be referred to herein as a top surface, but may be a side surface or bottom surface depending on orientation of the LED lighting system  250 . In some embodiments, all or portions of the metal layer  206  and/or silicon backplane  204  may be embedded in the substrate  208 . The substrate  208  may have an opening that exposes inner surfaces  217   a ,  217   b  of the substrate  208 . The opening may extend completely through an entire thickness, T, of the substrate  208 . Depending on the shape, the opening may have any number of inner surfaces or a single inner surface  217 , which may be a top surface, bottom surface, etc. depending on orientation of the LED lighting system  250 . In the example illustrated in  FIG.  2 B , the hybridized device  200  is placed with at least the metal inlay  210  in the opening and the side surfaces of the metal inlay  210  contacting the inner surfaces  217   a ,  217   b  of the substrate  208 . In such embodiments, the hybridized device  200  may be secured to the inner surfaces  217   a ,  217   b  of the substrate  208  via a suitable adhesive. In other embodiments, the substrate  208  may be molded around the hybridized device  200  such that the side surfaces of at least the metal inlay  210  are in direct contact with the inner surfaces  217   a ,  217   b  of the substrate  208 . In other embodiments, the opening may be wider than the hybridized device  200  and may leave a space between the inner surfaces  217   a ,  217   b  and the side surfaces of at least the metal inlay  210 . 
     The illustrated LED lighting system  250  may also include a metal pad  218  thermally coupled to the second surface  211  of the metal inlay  210 , which may be a part of or separate and attached to the metal inlay  210 . The metal pad  218  may facilitate connection between the metal inlay  210  and another circuit board, another metal inlay and/or a heat sink. In embodiments, the metal pad  218  may not be included, and the metal inlay  210  may be placed in direct contact with another circuit board, another metal inlay and/or a heat sink. In the illustrated embodiment, the metal pad  218  completely covers the second surface  211  of the metal inlay  210  and overlaps a portion of a second surface  215  of the substrate  208 . The second surface  211  may also be referred to as a bottom surface, but may be a top surface, side surface, etc. depending on orientation of the LED lighting system  250 . One of ordinary skill in the art will understand that the metal pad  218  may only partially cover the second surface  211  of the metal inlay  210 , may completely cover the second surface  211  of the metal inlay  210  without overlapping the second surface  215  of the substrate or may extend further to cover a larger area of the second surface  215  of the substrate  208 . 
     Passive components  216  may be mounted on the first surface  213  of the substrate  208 . In the example illustrated in  FIG.  2 B , the passive components  216  are mounted on first metal pads (not shown) on the first surface  213 . Second metal pads or contacts  220  may also be provided on the first surface  213  of the substrate  208 . The silicon backplane  204  may also be electrically coupled to the passive components  216  and the second metal pads or contacts  220  via conductive connectors  212 . Although not shown in  FIG.  2 B , additional metallizations on the first surface  213  of the substrate  208  may complete the electrical connection between the silicon backplane  204 , the conductive connectors  212  and respective passive components  216 . Examples of the metallizations are shown and described below with respect to  FIGS.  4 A and  4 B . The second metal pads or contacts  220  may make an electrical connection between the silicon backplane  204  and power sources and/or other electronic components on a second substrate or circuit board (example of which are shown in  FIGS.  3 A and  3 B ). 
     Although only two conductive connectors  212  are shown in  FIG.  2 B , any number of conductive connectors  212  may be included. For example, the LED lighting system  250  may include 27 or more passive components  216  and an equal or greater number of conductive connectors  212 . In the illustrated embodiment, the conductive connectors  212  are wires, such as ribbon wires. However, the conductive connectors  212  may be any suitable type of conductive connector, such as flexible circuit. The conductive connectors may be completely covered by an encapsulant material  214 . The encapsulant material  214  may protect the conductive connectors  212  and, in embodiments, may also serve the function of providing contrast, for example for an image displayed via the LED array  202 . In embodiments, the encapsulant may be an epoxy or silicone material that has a carbon filler that may create a dark or black appearance. The encapsulant material may also be referred to herein as a light-blocking encapsulant. 
       FIG.  3 A  is a cross-sectional view of an application system  300 A that incorporates the LED lighting system  250  of  FIG.  2 B . The application system  300 A may include a circuit board  222  that has a number of metal pads  233  on a first surface  301 . The circuit board  222  may house control and/or other circuitry and may also be referred to herein as a control board. The metal pads  233  may be in locations that enable electrical coupling with the first metal pads or contacts  220  (not shown in  FIG.  3 A ) on the first surface  213  of the substrate  208 . As illustrated in  FIG.  3 A , the circuit board  222  defines an opening, and the LED lighting system  250  is disposed in the opening with a gap between outer edges of the substrate  222  and inner surfaces of the circuit board  222  exposed by the opening. In embodiments, however, the gap may be smaller, larger, or non-existent. 
     In the example illustrated in  FIG.  3 A , both the substrate  208  and the circuit board  222  are on top of a heat sink  232  and thermally coupled to the heat sink  232  via a thermal interface material (TIM)  228 . The metal pads or contacts  220  may be electrically coupled to the metal pads  233  on the first surface  301  of the circuit board  222  via conductive connectors  224 . In the illustrated embodiment, the conductive connectors  224  are wires, such as ribbon wires. However, the conductive connectors  224  may be any suitable type of conductive connector, such as flexible circuit. The conductive connectors  224  may be completely covered by an encapsulant material  226 . The encapsulant material  214  may protect the conductive connectors  212  and, in embodiments, may also serve the function of providing contrast, for example for an image displayed via the LED array  202 . In embodiments, the encapsulant may be an epoxy or silicone material that has a carbon filler that may create a dark or black appearance. The encapsulant material may also be referred to herein as a light-blocking encapsulant. 
     The heat sink  232  may also include a metal inlay  230 , which may include a metal pad located to correspond with the metal pad  218  of the LED lighting system  250 . The placement of the metal inlay  210  of the LED lighting system  250  in close proximity to and in thermal coupling with the heat sink  232 , and in particular in close proximity to and thermal coupling with a metal inlay  230  in the heat sink  232 , where included, may enable good heat transfer from the hybridized device  200  to the heat sink  232  via the second or bottom surfaces  203 ,  207  and  211  of the LED array  202 , the silicon backplane  204  and the metal inlay  210 . 
     Additionally, the electrical coupling between the metal contacts or pads  220  and corresponding metal pads  233  on the circuit board  222  may enable electrical coupling between the passive components  216 , the silicon backplane  204  and the circuit board  222 . The circuit board  222  may be part of a larger system used in specific applications, such as vehicle lighting or flash applications (example vehicle lighting systems are described below with respect to  FIGS.  5  and  6   ). The circuit board  222  may include other circuit elements required for the larger system in addition to the heat sink  232 . In embodiments, the metal inlay  230  may be located in the heat sink  232  in any of the ways mentioned above with respect to the metal inlay  210  of the LED lighting system  250 . 
       FIG.  3 B  is a cross-sectional view of another application system  300 B that incorporates the LED lighting system  250  of  FIG.  2 B . As in the application system  300   a , the application system  300 B may include a circuit board  222  that has a number of metal pads  233  on a first surface  301  (not labeled in  FIG.  3 B ). The metal pads  233  may be in locations that enable electrical coupling with the metal pads or contacts  220  on the first surface  213  of the substrate  208 . As opposed to  FIG.  3 A , however, in which the LED lighting system  250  is disposed in an opening in the circuit board  222 , in the application system illustrated in  FIG.  3 B , the LED lighting system  250  is mounted on top of the circuit board  222 . In the example illustrated in FIG.  3 B, the LED lighting system  250  is disposed over the circuit board  222  and thermally coupled thereto via a thermal interface material (TIM)  228 . 
     In some embodiments, the circuit board  222  defines an opening, and a second metal inlay  230  is embedded in the opening. In embodiments, the second metal inlay  230  may be located in the circuit board  222  in any of the ways mentioned above with respect to the metal inlay  210  of the LED lighting system  250 . The LED lighting system  250  is mounted on the circuit board  222  with the metal inlays  210  and  230  aligned. The placement of the metal inlay  210  of the LED lighting system  250  in close proximity to and in thermal coupling with the circuit board  222 , and in particular in close proximity to and thermal coupling with a metal inlay  230  in the circuit board  222 , where included, may enable good heat transfer from the hybridized device  200  to the circuit board  222  via the second or bottom surfaces  203 ,  207  and  211  of the LED array  202 , the silicon backplane  204  and the metal inlay  210 . 
     In the example illustrated in  FIG.  3 B , the circuit board  222  is further mounted on top of a heat sink  232 . The metal pads or contacts  220  may be electrically coupled to the metal pads  233  on the first surface  301  of the circuit board  222  via conductive connectors  224 . In the illustrated embodiment, the conductive connectors  224  are wires, such as ribbon wires. However, the conductive connectors  224  may be any suitable type of conductive connector, such as flexible circuit. The conductive connectors  224  may be completely covered by an encapsulant material  226 . The encapsulant material  226  may protect the conductive connectors  224  and, in embodiments, may also serve the function of providing contrast, for example for an image displayed via the LED array  202 . In embodiments, the encapsulant may be an epoxy or silicone material that has a carbon filler that may create a dark or black appearance. The encapsulant material may also be referred to herein as a light-blocking encapsulant. 
     Additionally, the electrical coupling between the metal contacts or pads  220  and corresponding metal pads on the circuit board  222  may enable electrical coupling between the passive components  216 , the silicon backplane  204  and the circuit board  222 . The circuit board  222  may be part of a larger system used in specific applications, such as vehicle lighting or flash applications (example vehicle lighting systems are described below with respect to  FIGS.  5  and  6   ). The circuit board  222  may include other circuit elements required for the larger system in addition to the heat sink  232 . 
     In the embodiments in both of  FIGS.  3 A and  3 B , top surface contacts are used to make the electrical connection between the LED lighting system  250  and the circuit board  222 . This may be an inexpensive way of making the connection and may also enable use of a larger board to house the passive electronic components, surface metallizations, conductive connectors and any other required or desired elements.  FIGS.  3 A and  3 B  are not shown to scale and the arrows in  FIG.  3 B  denote that the circuit board  222  is drawn smaller than it may actually be and may be much larger than shown in the illustration. 
       FIG.  4 A  is a top view showing a top surface  400  of the LED lighting system  250  of  FIG.  2 B . The top view shows a first or top surface of the LED array  202 , a portion of the first or top surface  205  of the silicon backplane  204  that is not covered by the LED array  202 , the encapsulant  214  covering the conductive connectors  212 , the passive components  216 , the contacts or pads  220 , metallizations  234  that electrically couple the conductive connectors  212  to respective ones of the passive components  216  or the contacts or pads  220 , and portions of the first or top surface  213  of the substrate  208  that are not covered by the silicon backplane  204 , the encapsulant  214 , the metallizations  234 , the passive components  216  or the contacts or pads  220 . The metallizations  234  may be layers of metal that are patterned or etched to form electrical connections between contacts, pins or pads to which the conductive connectors (not shown) are attached and the passive components  216  or metal contacts or pads  220 . 
     As shown in  FIG.  4 A , the LED lighting system  250  has a length l 1  and a width w 1 . In embodiments, the length l 1  may be approximately 20 mm to 40 mm and the width w 1  may be approximately 20 mm to 40 mm. The silicon backplane  204  may have a length l 2  and a width w 2  (not labeled for clarity). In embodiments, the length l 2  may be approximately 15.5 mm and the width w 2  may be approximately 6.5 mm. The LED array  202  may have a length l 3  and a width w 3 . In embodiments, the length l 3  may be approximately 11 mm and the width w 3  may be approximately 4.4 mm. 
     Given these example dimensions, an LED array package may be provided that has a large surface area (400 mm 2  to 1600 mm 2  in the above example) with a large amount of the surface area not taken up by the LED array (which has a surface area of approximately 100 mm 2  in the above example). Accordingly, this design provides ample space for attachment of the passive electronic components on the LED array package. 
       FIG.  4 B  is a top view showing a top surface  450  of the application system  300   a  or  300   b  of  FIGS.  3 A and  3 B . In the example illustrated in  FIG.  4 B , the LED lighting system  250  is mounted on a top surface of the circuit board  222 . The encapsulant material  226  covering the conductive connectors  224  is also shown. The contacts or pads  233  are electrically coupled to the conductive connectors  224  via metallizations  242 . 
     While top contacts, pads, passive components, and metallizations are shown in specific locations on particular sides of the substrate  208  and circuit board  222  in  FIGS.  4 A and  4 B , one of ordinary skill in the art will recognize that more or less of these elements may be included and may be on all sides, less sides or in different locations than shown. 
     As mentioned above, the silicon backplane may include circuitry to receive power from one or more sources to power various portions of the silicon backplane, circuitry to receive image input from one or more sources for displaying an image via the LED array, circuitry for communications between the silicon backplane and external controllers (e.g., vehicle headlamp controls, general lighting controls, etc.), circuitry for generating a signal, such as a pulse width modulated (PWM) signal, for controlling operation of the individual LEDs or emitters in the array based on, for example, received image input and communications received from external sources and a number of LED drivers for individually driving the LEDs or emitters in the array based on the generated signal. For the communications, the silicon backplane may have a large number of digital interfaces and, thus, may require a large number (e.g., one hundred or more) physical connection pins for connecting to an external board or device. In some embodiments, the external board or device may be a vehicle headlamp, which may be communicatively coupled to various control modules in an automobile to receive control signals. 
     Additionally, the silicon backplane may require up to three or more power supplies, such as a digital power supply, an analog power supply and an LED power supply. Each power supply may require at least one individual de-coupling capacitor, and sometimes five or more de-coupling capacitors. In addition, the silicon backplane may require resistors to precisely set LED current, other non-de-coupling capacitors, and/or a crystal to set a frequency for a universal asynchronous receiver-transmitter (UART). Many or all of these passive components should be placed as closely as possible to the silicon backplane pins. For example, the crystal used to set the frequency for the UART may have a very high frequency, which may be sensitive to noise. Additionally, each of these passive components may need to be electrically coupled to the silicon backplane. 
       FIG.  5    is a diagram of an example vehicle headlamp system  500  that may incorporate the LED lighting system  250  of  FIG.  2 B . The example vehicle headlamp system  500  illustrated in  FIG.  5    includes power lines  502 , a data bus  504 , an input filter and protection module  506 , a bus transceiver  508 , a sensor module  510 , an LED direct current to direct current (DC/DC) module  512 , a logic low-dropout (LDO) module  514 , a micro-controller  516  and an active head lamp  518 . In embodiments, the active head lamp  518  may include an LED lighting system, such as the LED lighting system  250  of  FIG.  2 B . 
     The power lines  502  may have inputs that receive power from a vehicle, and the data bus  504  may have inputs/outputs over which data may be exchanged between the vehicle and the vehicle headlamp system  500 . For example, the vehicle headlamp system  500  may receive instructions from other locations in the vehicle, such as instructions to turn on turn signaling or turn on headlamps, and may send feedback to other locations in the vehicle if desired. The sensor module  510  may be communicatively coupled to the data bus  504  and may provide additional data to the vehicle headlamp system  500  or other locations in the vehicle related to, for example, environmental conditions (e.g., time of day, rain, fog, or ambient light levels), vehicle state (e.g., parked, in-motion, speed of motion, or direction of motion), and presence/position of other objects (e.g., vehicles or pedestrians). A headlamp controller that is separate from any vehicle controller communicatively coupled to the vehicle data bus may also be included in the vehicle headlamp system  500 . In  FIG.  5   , the headlamp controller may be a micro-controller, such as micro-controller (pc)  516 . The micro-controller  516  may be communicatively coupled to the data bus  504 . 
     The input filter and protection module  506  may be electrically coupled to the power lines  502  and may, for example, support various filters to reduce conducted emissions and provide power immunity. Additionally, the input filter and protection module  506  may provide electrostatic discharge (ESD) protection, load-dump protection, alternator field decay protection, and/or reverse polarity protection. 
     The LED DC/DC module  512  may be coupled between the filter and protection module  506  and the active headlamp  518  to receive filtered power and provide a drive current to power LEDs in the LED array in the active headlamp  518 . The LED DC/DC module  512  may have an input voltage between 7 and 18 volts with a nominal voltage of approximately 13.2 volts and an output voltage that may be slightly higher (e.g., 0.3 volts) than a maximum voltage for the LED array (e.g., as determined by factor or local calibration and operating condition adjustments due to load, temperature or other factors). 
     The logic LDO module  514  may be coupled to the input filter and protection module  506  to receive the filtered power. The logic LDO module  514  may also be coupled to the micro-controller  516  and the active headlamp  518  to provide power to the micro-controller  516  and/or the silicon backplane (e.g., CMOS logic) in the active headlamp  518 . 
     The bus transceiver  508  may have, for example, a universal asynchronous receiver transmitter (UART) or serial peripheral interface (SPI) and may be coupled to the micro-controller  516 . The micro-controller  516  may translate vehicle input based on, or including, data from the sensor module  510 . The translated vehicle input may include a video signal that is transferrable to an image buffer in the active headlamp module  518 . In addition, the micro-controller  516  may load default image frames and test for open/short pixels during startup. In embodiments, an SPI interface may load an image buffer in CMOS. Image frames may be full frame, differential or partial frames. Other features of micro-controller  516  may include control interface monitoring of CMOS status, including die temperature, as well as logic LDO output. In embodiments, LED DC/DC output may be dynamically controlled to minimize headroom. In addition to providing image frame data, other headlamp functions, such as complementary use in conjunction with side marker or turn signal lights, and/or activation of daytime running lights, may also be controlled. 
       FIG.  6    is a diagram of another example vehicle headlamp system  600 . The example vehicle headlamp system  600  illustrated in  FIG.  6    includes an application platform  602 , two LED lighting systems  606  and  608 , and optics  610  and  612 . The two LED lighting systems  606  and  608  may be LED lighting systems, such as the LED lighting system  250  of  FIG.  2 B , or may include the LED lighting system  250  plus some of all of the other modules in the vehicle headlamp system  500  of  FIG.  5   . In the latter embodiment, the LED lighting systems  606  and  608  may be vehicle headlamp sub-systems. 
     The LED lighting system  608  may emit light beams  614  (shown between arrows  614   a  and  614   b  in  FIG.  6   ). The LED lighting system  606  may emit light beams  616  (shown between arrows  616   a  and  616   b  in  FIG.  6   ). In the embodiment shown in  FIG.  6   , a secondary optic  610  is adjacent the LED lighting system  608 , and the light emitted from the LED lighting system  608  passes through the secondary optic  610 . Similarly, a secondary optic  612  is adjacent the LED lighting system  606 , and the light emitted from the LED lighting system  606  passes through the secondary optic  612 . In alternative embodiments, no secondary optics  610 / 612  are provided in the vehicle headlamp system. 
     Where included, the secondary optics  610 / 612  may be or include one or more light guides. The one or more light guides may be edge lit or may have an interior opening that defines an interior edge of the light guide. LED lighting systems  608  and  606  (or the active headlamp of a vehicle headlamp sub-system) may be inserted in the interior openings of the one or more light guides such that they inject light into the interior edge (interior opening light guide) or exterior edge (edge lit light guide) of the one or more light guides. In embodiments, the one or more light guides may shape the light emitted by the LED lighting systems  608  and  606  in a desired manner, such as, for example, with a gradient, a chamfered distribution, a narrow distribution, a wide distribution, or an angular distribution. 
     The application platform  602  may provide power and/or data to the LED lighting systems  606  and/or  608  via lines  604 , which may include one or more or a portion of the power lines  502  and the data bus  504  of  FIG.  5   . One or more sensors (which may be the sensors in the example vehicle headlamp system  500  or other additional sensors) may be internal or external to the housing of the application platform  602 . Alternatively or in addition, as shown in the example vehicle headlamp system  500  of  FIG.  5   , each LED lighting system  608  and  606  may include its own sensor module, connectivity and control module, power module, and/or LED array. 
     In embodiments, the vehicle headlamp system  600  may represent an automobile with steerable light beams where LEDs may be selectively activated to provide steerable light. For example, an array of LEDs (e.g., the LED array  102 ) may be used to define or project a shape or pattern or illuminate only selected sections of a roadway. In an example embodiment, infrared cameras or detector pixels within LED lighting systems  606  and  608  may be sensors (e.g., similar to sensors in the sensor module  510  of  FIG.  5   ) that identify portions of a scene (e.g., roadway or pedestrian crossing) that require illumination. 
       FIG.  7    is a flow diagram of an example method  700  of manufacturing an LED lighting system, such as the LED lighting system  250  of  FIG.  2 B . 
     In the example method  700  of  FIG.  7   , a thermally conductive inlay may be embedded in a first substrate ( 702 ). In embodiments, this may be done by placing the thermally conductive inlay in an opening in the first substrate. In some embodiments, the thermally conductive inlay may be adhered to exposed inner side surfaces of the substrate using an adhesive or may be pressure fit. In some embodiments, the substrate may be molded around the thermally conductive inlay. Passive components may be surface mounted on the first substrate ( 704 ). In embodiments, the passive components may be mounted, for example by soldering, on at least some of a number of metal contacts on a first or top surface of the first substrate. In embodiments, vias and other surface metallization may already be formed on the first substrate when the thermally conductive inlay is embedded or may be formed after. 
     An LED array, such as a micro-LED array, may be attached to a first or top surface of a silicon backplane ( 706 ). In embodiments, the LED array may include an array of connectors, such as copper pillar bumps, and they may be individually coupled to drivers in the silicon backplane by soldering, reflow or other methods. A thermally conductive material may be dispensed on the first substrate ( 708 ). In embodiments, the thermally conductive material may be dispensed on at least a metal pad attached to or part of the thermally conductive inlay. In other embodiments, the thermally conductive material may be dispensed directly on at least the thermally conductive inlay. In some embodiments, the thermally conductive material may cover an entirety of the first or top surface of the first substrate. In embodiments, the thermally conductive material may be silver. The backplane with the LED array attached may be die attached to the first substrate ( 710 ), for example by placing it on the thermally conductive material and allowing it to cure. 
     The backplane may be wirebond attached to the first substrate ( 712 ). This may be done, for example, using ribbon wire, flexible circuit, or other connector and soldering or otherwise electrically coupling metal contacts, pads or pins on the backplane to metal contacts, pads or pins on the first or top surface of the first substrate. An encapsulant material, such as described in detail above, may be dispensed on or molded around the wirebonds ( 714 ) (e.g., ribbon wires, flexible circuits, or other conductive connectors). In embodiments, this may result in the wirebonds being completely covered by the encapsulant material. 
     A second substrate (e.g., a circuit board) may be attached to a heat sink ( 716 ), for example using a thermally conductive material such as a TIM. In some embodiments, the first substrate may be embedded in the second substrate ( 718   a ). In such embodiments, this may be done by placing the first substrate in an opening in the second substrate, and attaching the first substrate to a first or top surface of the heat sink, using a thermally conductive material, such as a TIM. In embodiments, the second substrate may have an embedded second thermal inlay, which may include or have a separately attached metal pad, and the first and second metal inlays may be soldered together. The second metal inlay may be embedded in the heat sink, for example, by placing it in an opening in the heat sink and either pressure fitting or bonding the second metal inlay to the heat sink. 
     In other embodiments, the first substrate may be surface mounted on a second substrate ( 718   b ). In embodiments, metal pads or contacts on the second or bottom surface of the first substrate may be soldered or otherwise electrically coupled to metal pads or contacts on a first or top surface of the second substrate. Further, in some embodiments, a thermally conductive inlay embedded in the second substrate may be thermally coupled to the thermally conductive inlay embedded in the first substrate, for example by soldering pads on or part of both thermally conductive inlays together or directly soldering the thermally conductive inlays together. 
     The first substrate may be wirebonded to the second substrate ( 720 ). This may be done, for example, using ribbon wire, flexible circuit, or other connector and soldering or otherwise electrically coupling metal contacts, pads or pins on the first substrate to metal contacts, pads or pins on the first or top surface of the second substrate. An encapsulant material, such as described in detail above, may be dispensed on or molded around the wirebonds (e.g., ribbon wires, flexible circuits, or other conductive connectors). In embodiments, this may result in the wirebonds being completely covered by the encapsulant material. 
     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.