Patent Publication Number: US-2021184084-A1

Title: Phosphor deposition system for leds

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation application of U.S. patent application Ser. No. 15/857,153 filed on Dec. 28, 2017, which is a national stage entry of International Application No. PCT/EP2016/064987 filed on Jun. 28, 2016, which claims the benefit of priority from U.S. Provisional Application No. 62/188,009 filed on Jul. 2, 2015. Each of the above applications are incorporated herein by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure relates to color changing light-emitting device packages. 
     BACKGROUND 
     Addressable Color Changeable LED Structure 
     There are several ways to construct a color changing light-emitting device package. A number of individual light-emitting diodes (LEDs) of different colors can be placed under a single primary optic. However, this presents difficulties in mixing the colors. If there is no mixing, some primary optics will project the different colors into different directions. When mixing is added, it makes the effective source size larger or compromises the design of the primary optics. The result is that either the beam control is worsened or a larger primary optic is required. These affect the overall performance, form factor, and price of the package. 
     Alternatively, a number of individual LEDs of different colors can be each placed under its own primary optic. In this case, the beams may not completely overlap, especially at close distances. This can create a color artifact near the border of shadows. Also, this introduces a limitation on the optical design. More than one primary optic is needed and this may not be preferred aesthetically. This is the current solution for color-changing flash modules. 
     A LED light source based on LED pixels has been discussed for displays, such as a low power addressable LED arrays for color changeable displays. U.S. Pat. No. 9,041,025 discloses LED pixels arranged in groups of four pixels, with the LEDs emitting a single color of light for all pixels. A mold positioned over the LED pixels accepts phosphors for the individual LED pixels in each group. The phosphors in the mold transmit at least three (3) primary colors for respective ones of the LED pixels in each group. A fourth LED pixel in the group can transmit white light. 
     High Power Addressable LED Structure 
     A LED light source based on addressable individual or groups of LED pixels that can be turned on or off has been discussed. 
     A number of individual LEDs can be placed near each other in an array, each under their own primary optic. However, this requires a large number of LEDs and primary optics, and will take a lot of space. 
     Osram&#39;s Micro Advanced Forward-lighting System (μAFS) concept discloses a multi pixel flip chip LED array directly mounted to an active driver integrated circuit (IC). A total of 1024 pixels can be individually addressed through a serial data bus. Several of these units can be integrated in a prototype headlamp to enable advanced light distribution patterns in an evaluation vehicle. 
     Vehicle manufacturers have realized the advantages of selectively addressable LED arrays for headlights. For example, U.S. Pat. No. 8,314,558 discloses a vehicle headlamp having a plurality of LEDs positioned into an array. The array has at least one row and at least two columns with each LED positioned at an intersection of a row and a column. A LED is illuminated by selectively applying a signal to the row and a signal to the column corresponding to the position of the LED. 
     High Tuneability LEDs with Phosphors Deposited on Wafer 
     It is difficult to coat different types of phosphors on LED pixels on the same wafer or tile when the LED pixels are in close proximity to each other. Phosphors for one LED pixel may spill over and mix with phosphors of a neighboring LED pixel. Furthermore, light crosstalk between phosphors of neighboring LED pixels varies the color endpoints between packages and reduces the range of color tuneability between the color endpoints. 
     Improved Phosphor Deposition System for LEDs 
     The use of multi-chip LED fixtures to improve color intermixing has been discussed. For example, Acclaim Lighting describes a color mixing application using a single lens to produce a homogenized beam with blended color and minimal color halos or shadowing. Such multi-chip packages are available from Cree, Osram, Prolight Opto Technology, and Opto Tech Corp. 
     SUMMARY 
     Addressable Color Changeable LED Structure 
     Some examples of the present disclosure provide a color changing light-emitting device package. Since there is only one LED die in the package, only one optic is needed. 
     The LED die is made of a number of segments, each emitting a different color of light. The amount of light emitted from each segment can be changed. The result is a change in the average color of the whole LED die. The segments are placed close together to enable efficient color mixing in the optic outside of the LED die. This means that better optical control can be achieved with a smaller optic, which reduces cost and form factor. 
     The segments can consist of a single junction or multiple junctions. In a simple example, a LED die is divided into two segments of different colors, each consisting of an individually controlled junction. In a more complicated example, a LED die is divided into two segments of different color, each consisting of nine (9) junctions in parallel or in series. 
     The multiple junctions in a single segment can be continuous or discontinuous. For example, in the case of two different color segments each consisting of nine (9) individual junctions, the junctions of different segments (colors) may be interspersed (placed among each other) randomly or in a regular pattern. A regular pattern may be a checkerboard pattern with alternating color junctions, serpentine segments that spiral outward and encircle each other, or concentric circular segments of different (alternating) color junctions. 
     The segments define the borders of the color tuneable region of the LED die. If there are two segments of different colors, then the average color can be tuned to either of these endpoint colors or any color on a straight line between the endpoint colors. If there are three segments of different colors, the color gamut is defined by a triangle with corners having the colors of the individual segments. More segments will result in more shapes in the color space. In some examples, each segment may have a different spectral content. This means that all segments may have the same color but some might have different color rendition index (CRI) or R9 (red) values. 
     The junctions of each color should be small and preferably interspersed randomly or in a regular pattern. From an application&#39;s viewpoint, it is better to have the colors interspersed like a checkerboard, rather than have a few large junctions of all one color. The size of a single junction of a color segment should be small. From an application&#39;s viewpoint, it is better to have the LED die divided into a 50×50 checkerboard grid of two colors than a 2×2 grid of two colors. On the other hand, the grid with fewer, larger elements is easier to manufacture. In some examples, an LED die includes individual colored junctions of about 50 to 200 micrometers (μm) in width/height and has a grid size on the order of 4 to 20 elements×4 to 20 elements. In other examples, an LED die includes individual colored junctions of about 50 to 500 μm in width/height. The size or number of individual junctions does not need to be uniform. 
     The electrodes of the LED die are routed to the perimeter, where they can be accessed by one or more drivers. There are a number of ways to wire this. 
     The junctions may share a common cathode. The anode of each junction is individually routed to the perimeter. The cathode connection can be made on the LED level (when the junctions are not physically separated) or on the package level. 
     The junctions may share a common anode. The cathode of each junction is individually routed to the perimeter. The anode connection can be made on the LED level (when the pixels are not physically separated) or on the package level. 
     All the junctions may be connected in series. The traces that connect each pair of junctions are also routed to the perimeter, as well as the two unpaired connections. In this way, any junction can be shorted out, turning it off. Dimming can still be achieved with a pulse width modulation scheme. 
     One group of junctions may be connected using any of the above methods, and other groups are separately connected using any of the above methods. For example, the first row of junctions can be connected in series, and the second row of junctions can also be connected in series but in a different string. 
     All of the above routing may apply to the LED die as a whole, or may apply to the junctions of a certain segment (color). For instance, all of the junctions of one color may be in a series string, and all of the segments of a different color may be in a separate series string. 
     All LED junctions of a certain segment (color) may be connected in parallel. For instance, all of the junctions of color 1 can be in a single parallel string, and the junctions of color 2 can be a separate parallel string. 
     All traces are routed to the perimeter. This offers ultimate driver flexibility, since any of the above configurations can be made outside of the package. 
     High Power Addressable LED Structure 
     Some examples of the present disclosure provide a light-emitting device package with a single LED die having addressable junctions. Each junction can be addressed either individually or in groups (segments). The junctions can be independently turned on, turned off, or “dimmed” to an intermediate value. This enables beam steering, spot reduction, highlighting and dynamic effect features. 
     When the source package is imaged through a secondary imaging optic, the beam pattern is changed. The changing beam pattern can be used in a number of ways. The beam can be steered from one location to another. Parts of the beam can be turned up to highlight a location. Parts of the beam can be turned down or off to reduce or eliminate light in a place where it is not wanted. For instance, parts of the beam can be turned down or off to reduce glare. It can also save energy by only generating the light that is needed. A dynamic effect can be created. This may highlight something, illuminate a moving object, or may be used for artistic effect. 
     The junctions may be completely isolated from each other, or they can share a common cathode or common anode. 
     The junctions are arranged as closes as possible while still enabling phosphor deposition with an acceptable amount of phosphor spill-over from adjacent junctions and light crosstalk. For example, the active regions of two adjacent junctions are 1 to 100 μm apart, such as 37.9 μm apart in one direction and 25.9 μm apart in an orthogonal direction. This may be accomplished by attaching the junctions at once, as a monolithic array, still all joined together. The junctions may be separated after the attach process, such as through a laser-liftoff of their growth substrate. 
     The array may be used as-is or a wavelength converting layer can be applied. This may be used to make an array of white pixels. 
     Traces to the junctions are routed to the perimeter, where they may be accessed by one or more drivers. 
     As described above, some examples of the present disclosure enable low cost beam steering without requiring large separate packages with individual optical elements. The light-emitting device package allows the use of a ceramic substrate, which provides more freedom in choosing the cost, thermal expansion coefficient (influencing integration into a system), thermal resistance, and mechanical robustness. 
     Some examples of the present disclosure use smaller numbers of LEDs to achieve a pixilated light source. For instance, if one desires 18 pixels, the discrete LED case will require 18 LEDs. If each LED must be 0.5 mm 2 , then the total LED area is 9 mm 2 . Compare this to a single multi junction LED of only 2 mm 2 . 
     Some examples of the present disclosure use fewer optics, fewer attach steps, and fewer optic alignment steps. There is one LED die attach and one optic, compared to many LEDs to attach and many optics. This also results in a lower cost for the light-emitting device package, especially in cases where large numbers of LED dies would result in under-driving the LEDs. 
     The size of the optics and source is also smaller. In the discrete LED case, a large array of optics is required whereas the light-emitting device package uses only one optic. The size of the optic may be larger than what is required for a single standard LED but it is not as large as the array of optics. In some applications, there is not enough space for a large array of optics. In some applications, there is an aesthetic value in reducing the size of the combined optics. 
     High Tuneability LEDs with Phosphors Deposited on Wafer 
     Some examples of the present disclosure provide discrete strings, lines, or blocks of a transparent conductor such as antimony tin oxide (ATO), indium tin oxide (ITO), or silver nanowires capable of being deposited on a growth substrate of an LED die with multiple junctions. Each grouping of transparent conductor can be deposited in separate, distinct lines or blocks. Complex curved, circular, or winding layouts are possible. 
     With application of a voltage to a particular transparent conductor string, phosphors may be electrophoretically deposited only on the transparent conductor. Varying voltage duration will correspondingly vary amount and thickness of deposited phosphors. 
     Separation of phosphor lines may be adjusted by increasing or decreasing width of underlying transparent conductor string. 
     Some examples of the present disclosure provide for low cost wafer level deposition of phosphors on sapphire. Multiple types and thicknesses of phosphors can be used. When singulating the wafer into LED dies, variation due to phosphor crosstalk is minimized to improve color tuneability. 
     Improved Phosphor Deposition System for LEDs 
     In some examples of the present disclosure, phosphors are applied by electrophoretic deposition (EPD) to specific junctions. A voltage can be applied to specific groups of electrically connected junctions. Discrete strings, lines, blocks, complex curves, circular, winding, or checkerboard layouts are possible. Varying the voltage during the deposition or the duration of the deposition may correspondingly vary amount and thickness of deposited phosphors. 
     To reduce risk of electrical sparking between closely spaced junctions during EPD, adjacent junctions can be held at a non-zero voltage. For example, a first string of junctions can be held at 800 volts during EPD while adjacent junctions are held at 400 volts rather than 0 volts. 
     If a sharp transition in amount, type, or thickness of phosphor is desired between closely spaced junctions, adjacent junctions can also be held at opposite voltage during EPD. For example, a first string of junctions can be held at 800 volts during EPD while adjacent junctions are held at −400 volts rather than 0 volts. 
     In some examples, antishock or insulating layers can be deposited between junctions prior to high voltage EPD. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1-1  is a top view of a light-emitting diode (LED) die in some examples of the present disclosure. 
         FIG. 1-2  is a cross-sectional view of the LED die of  FIG. 1  in some examples of the present disclosure. 
         FIGS. 2 and 3  illustrate the assembly of a light-emitting device package in some examples of the present disclosure. 
         FIG. 4  is a top view of a metalized substrate in some examples of the present disclosure. 
         FIG. 5  illustrates in phantom the placement of junctions in the LED die of  FIG. 1-2  on pads of the metalized substrate of  FIG. 4  in some examples of the present disclosure. 
         FIG. 6  is a top view of a metalized substrate in some examples of the present disclosure. 
         FIG. 7  illustrates in phantom the placement of junctions in the LED die of  FIG. 1-2  on pads of the metalized substrate of  FIG. 6  in some examples of the present disclosure. 
         FIG. 8  is a top view of a metalized substrate in some example of the present disclosure. 
         FIG. 9  illustrates in phantom the placement of junctions in the LED die of  FIG. 1-2  on pads of the metalized substrate of  FIG. 8  in some examples of the present disclosure. 
         FIG. 10  is a cross-sectional view of a LED die in some examples of the present disclosure. 
         FIG. 11  is a cross-sectional view of a LED die in some examples of the present disclosure. 
         FIG. 12  illustrates in phantom the placement of junctions in the LED die of  FIG. 10 or 11  on the pads of the metalized substrate of  FIG. 4  in some examples of the present disclosure. 
         FIG. 13  illustrates in phantom the placement of junctions in the LED die of  FIG. 10  or  FIG. 11  on the pads of the metalized substrate of  FIG. 6  in some examples of the present disclosure. 
         FIG. 14  illustrates a pattern of transparent conductors on a growth substrate for forming wavelength converters using electrophoretic deposition (EPD) in some examples of the present disclosure. 
         FIG. 15-1  illustrates another pattern of transparent conductors on a growth substrate for forming wavelength converters using EPD in some examples of the present disclosure. 
         FIG. 15-2  illustrates wavelength converters having smaller footprint than the underlying junctions in some examples of the present disclosure. 
         FIG. 15-3  illustrates wavelength converters of different colors abutting each other in some examples of the present disclosure. 
         FIG. 16  is an International Commission on Illumination (CIE)  1976  color chart illustrating a hypothetical color tuning range of the LED die of  FIG. 1-2  having cool-white and warm-white phosphor layers in some examples of the present disclosure. 
         FIGS. 17 and 18  are top and bottom views, respectively, of a metalized substrate in some example of the present disclosure. 
         FIGS. 19-1 and 19-2  illustrate the placement of junctions in the LED die of  FIG. 1-2  on the metalized substrate of  FIG. 17  in some examples of the present disclosure. 
         FIG. 20  illustrates electrically connected strings of a metalized substrate that is a variation of the metalized substrate of  FIG. 17  in some examples of the present disclosure. 
         FIG. 21  is a flowchart of a method for making a light-emitting device package in examples of the present disclosure. 
         FIG. 22  is a flowchart of a method for making a LED die in examples of the present disclosure. 
         FIG. 23  illustrates applications of the light-emitting device package of  FIG. 3  in examples of the present disclosure. 
     
    
    
     Use of the same reference numbers in different figures indicates similar or identical elements. 
     DETAILED DESCRIPTION 
       FIG. 1-1  is a top view of a light-emitting diode (LED) die  100  in some examples of the present disclosure. LED die  100  may be a segmented or multi junction LED die. LED die  100  includes an array of junctions  102 - 1 ,  102 - 2 , . . . , and  102 - n  (collectively as “junctions  102 ” or individually as a generic “junction  102 ”) formed on a growth substrate  104 . The array of junctions  102  in LED die  100  is not limited to any size or shape. Trenches  106  down to growth substrate  104  surround junctions  102  to completely electrically insulate them from each other. Trenches  106  may be formed by wet etch, dry etch, mechanical saw, laser scribe, or another suitable technique. 
       FIG. 1-2  is a cross-sectional view of LED die  100  in some examples of the present disclosure. Each junction  102  has a semiconductor structure including an active region  108  between an n-type semiconductor layer  110  and a p-type semiconductor layer  112 . Each junction  102  has a cathode  114  coupled to its n-type semiconductor layer  110  by an ohmic p-contact through an opening in an insulator (dielectric) layer, and each junction  102  has an anode  116  coupled to its p-type semiconductor layer  112  by an ohmic n-contact through an opening in the insulator layer. Surface treatment may be performed on growth substrate  104 , such as photoelectrochemical (PEC) etching or mechanical roughening, or a thin film of anti-reflective coating may be applied. In some examples, growth substrate  104  is removed from LED die  100  after LED die  100  is mounted on another mechanical support. 
     LED dies  100  are formed on a growth wafer. The layers for the semiconductor structure of LED dies  100  are grown on the growth wafer, followed by the ohmic contacts and then the cathodes and the anodes. Trenches  106  are formed in these layers down to the growth wafer to create junctions  102  in each LED die  100 . Individual LED dies  100  are singulated from the resulting device wafer. 
     LED die  100  includes individual wavelength converters  118 . Wavelength converters may be phosphor layers or ceramic phosphor plates. Each wavelength converter  118  is located over a different junction  102 . Wavelength converters  118  are formed on growth substrate  104  or directly on junctions  102  when growth substrate  104  has been removed from LED die  100  after LED die  100  is mounted on another mechanical support. Wavelength converters  118  are made of a number of different materials to generate different colors of light, such as whites of different correlated color temperatures (CCTs) or primary colors of red, green, and blue. Instead of individual wavelength converters  118 , a single continuous wavelength converter of the same material may be used to generate a single color of light. Wavelength converters  118  may also be omitted so junctions  102  emit their native color(s) of light based on their bandgap energies. 
     Wavelength converters  118  may be formed on the growth wafer before LED dies  100  are singulated from the device wafer, or on growth substrates  104  after LED dies  100  are singulated from the device wafer. Alternatively, wavelength converters  118  are formed directly on junctions  102  in LED dies  100  after growth substrates  104  have been removed from LED dies  100  after LED dies  100  are mounted on other mechanical supports. 
       FIGS. 2 and 3  illustrate the assembly of a monochromatic or color changing light-emitting device package  300  in some examples of the present disclosure. Package  300  includes a LED die  100 , a metalized substrate  202 , and a primary optic  204 . LED die  100  is mounted on metalized substrate  202 , and primary optic  204  is mounted over LED die  100  on metalized substrate  202 . Instead of mounting LED die  100  on metalized substrate  202 , individual junctions  102  singulated from a device wafer maybe picked and placed on metalized substrate  202 . 
     Metalized substrate  202  is a single-layer or multi-layer tile, which may be made of aluminum nitride ceramic, aluminum oxide ceramic, or another suitable material. Metalized substrate  202  has a top surface  206 , top pads  208  on top surface  206 , top traces  210  on top surface  206 , and a bottom surface  212 . Top pads  208  are arranged about the center of top surface  206  to receive the electrodes (cathodes  114  and anodes  116 ) of junctions  102  in LED die  100 . Cathodes  114  and anodes  116  are attached to top pads  208  by gold-gold interconnect, large-area gold-gold interconnect, solder, or another suitable interconnect. Top traces  210  connect to top pads  208  and fan out to the perimeter of metalized substrate  202  where top traces  210  can be connected to external driving circuitry. Top traces  210  may connect certain top pad  208  from different junctions  102  in series, in parallel, or a combination thereof. 
     When metalized substrate  202  is a multi-layer tile, it may include bottom pads  214  on bottom surface  212  and vias  216  that connect top pads  208  to bottom pads  214 . Metalized substrate  202  may also include lower level (buried) traces  218  and vias  220  that connect top pads  208  to traces  218 . Traces  218  may connect certain top pad  208  from different junctions  102  in series, in parallel, or a combination thereof. Traces  218  may also fan out to the perimeter of metalized substrate  202  where they can be connected to external driving circuitry. 
     Primary optic  204  is a silicone hemispheric lens or flat window molded over LED die  100  on metalized substrate  202 . Alternatively, primary optic  204  is a preformed silicone or glass hemispheric lens or flat window mounted over LED die  100  on metalized substrate  202 . Primary optic  204  may include scattering particles. Although shown mounted on metalized substrate  202 , primary optic  204  may be spaced apart from metalized substrate. Typically, the primary optic is used to tune light extraction efficiency and radiation pattern of an LED. For a color changing light-emitting device package, the primary optic may also be used to tune the color saturation and color cross-talk of the package. For example, while a hemispheric lens may extract more light from LED die  100 , a flat window may create a more saturated color by recycling more of the pump (e.g., blue) light from LED die  100  through wavelength converters  118 . Primary optic  204  may be shaped to increase color saturation and reduce cross-talk between wavelength converters  118  of different materials. In some examples, primary optic  204  may be a beam homogenizer, such as a microlens array. 
       FIG. 4  is a top view of a metalized substrate  400  in some examples of the present disclosure. Metalized substrate  400  may be metalized substrate  202  in package  300  ( FIG. 3 ). Metalized substrate  400  is a single-layer tile. Metalized substrate  400  includes a 6 by 7 array of top pads  402  (only four are labeled), and top traces  404  connected to top pads  402 . Top traces  404  fan out to the perimeter of the metalized substrate  400 . To help understand the layout of top pads  402  and top traces  404 , a specific pad is identified by its row and column numbers, and a specific trace is identified by its pad&#39;s row and column numbers. For example, the first (leftmost) pad in the first (top) row is identified as  402 ( 1 , 1 ), and the trace to pad  402 ( 1 , 1 ) is identified as  404 ( 1 , 1 ). Cardinal directions are also used to describe the paths of top traces  404 . 
     In the first row of pads  402 , traces  404 ( 1 , 1 ) and  404 ( 1 , 7 ) fan out to the west and the east, respectively, toward the perimeter of metalized substrate  400 . Traces  404 ( 1 , 2 ) to  404 ( 1 , 6 ) fan out to the north toward the perimeter of metalized substrate  400 . 
     In the second row of pads  402 , traces  404 ( 2 , 1 ) and  404 ( 2 , 7 ) fan out to the west and the east, respectively, toward the perimeter of metalized substrate  400 . Trace  404 ( 2 , 2 ) fans out diagonally to the northwest and then to the west to pass between pads  402 ( 1 , 1 ) and  402 ( 2 , 1 ). Trace  404 ( 2 , 3 ) fans out to the north, then diagonally to the northwest, and finally to the north to pass between pads  402 ( 1 , 2 ) and  402 ( 1 , 3 ). Trace  404 ( 2 , 4 ) fans out to the north, then diagonally to the northwest, and finally to the north to pass between pads  402 ( 1 , 3 ) and  402 ( 1 , 4 ). Trace  404 ( 2 , 5 ) fans out to the north, then diagonally to the northeast, and finally to the north to pass between pads  402 ( 1 , 5 ) and  402 ( 1 , 6 ). Trace  404 ( 2 , 6 ) fans out diagonally to the northeast and then to the east to pass between pads  402 ( 1 , 7 ) and  402 ( 2 , 7 ). 
     In the third row of pads  402 , traces  404 ( 3 , 1 ) and  404 ( 3 , 7 ) fan out to the west and the east, respectively, toward the perimeter of metalized substrate  400 . Trace  404 ( 3 , 2 ) fans out diagonally to the northwest and then to the west to pass between pads  402 ( 2 , 1 ) and  402 ( 3 , 1 ). Trace  404 ( 3 , 3 ) fans out diagonally to the northwest and then to the north to pass between pads  402 ( 2 , 2 ) and  402 ( 2 , 3 ). Trace  404 ( 3 , 3 ) continues diagonally to the northwest, to the west to pass between pads  402 ( 1 , 2 ) and  402 ( 2 , 2 ), diagonally to the northwest, and finally to the north to pass between pads  402 ( 1 , 1 ) and  402 ( 1 , 2 ). Trace  404 ( 3 , 4 ) fans out diagonally to the northeast, to the north to pass between pads  402 ( 2 , 4 ) and  402 ( 2 , 5 ), and continues to the north to pass between pads  402 ( 1 , 4 ) and  402 ( 1 , 5 ). Trace  404 ( 3 , 5 ) fans out diagonally to the northeast and then to the north to pass between pads  402 ( 2 , 5 ) and  402 ( 2 , 6 ). Trace  404 ( 3 , 5 ) continues diagonally to the northeast, to the east to pass between pads  402 ( 1 , 6 ) and  402 ( 2 , 6 ), diagonally to the northeast, and finally to the north to pass between pads  402 ( 1 , 6 ) and  402 ( 1 , 7 ). Trace  404 ( 3 , 6 ) fans out diagonally to the northeast and then to the east to pass between pads  402 ( 2 , 7 ) and  402 ( 3 , 7 ). 
     Traces  404  for pads  402  in the fourth, the fifth, and the sixth rows mirror the configuration of traces  404  in the third, the second, and the first rows. 
       FIG. 5  illustrates in phantom the placement of junctions  102  (only six are labeled for clarity) in LED die  100  on pads  402  (only one is labeled) of metalized substrate  400  in some examples of the present disclosure. In this configuration, each junction  102  connects to a different pair of pads  402 . A dashed line indicates junctions  102  with a first type of wavelength converters  118  that emits a first color of light, and a dashed-double dotted line indicates junctions  102  with a second type of wavelength converters  118  that emits a second color of light. One or more junctions  102  that have the same type of wavelength converters  118  form a segment in LED die  100 . Junctions  102  from different segments (colors) intersperse with each other in a regular pattern, such as in a checkerboard pattern (as shown), serpentine segments that spiral outward and encircle each other, or concentric circular segments. Junctions  102  from different segments may also intersperse randomly. 
       FIG. 6  is a top view of a metalized substrate  600  in some examples of the present disclosure. Metalized substrate  600  may be metalized substrate  202  in package  300  ( FIG. 3 ). Metalized substrate  600  is a single-layer tile. Metalized substrate  600  includes a 4 by 10 array of top pads  602  (only six are labeled), and top traces  604  (only six are labeled) connected to pads  602 . Top traces  604  fan out to the perimeter of the metalized substrate  600 . To help understand the layout of top pads  602  and top traces  604 , a specific pad is identified by its row and column numbers, and a specific trace is identified by its pad&#39;s row and column numbers. Cardinal directions are also used to describe the paths of the top traces  604 . 
     In the first row of pads  602 , traces  604 ( 1 , 1 ) to  604 ( 1 , 10 ) fan out to the north toward the perimeter of metalized substrate  600 . 
     In the second row of pads  602 , traces  604 ( 2 , 1 ) to  604 ( 2 , 10 ) fan out diagonally to the northwest and then to the north toward the perimeter of metalized substrate  600 . In particular, trace  604 ( 2 , 2 ) passes between pads  602 ( 1 , 1 ) and  602 ( 1 , 2 ), trace  604 ( 2 , 3 ) passes between pads  602 ( 1 , 2 ) and  602 ( 1 , 3 ), . . . , and trace  604 ( 2 , 10 ) passes between pads  602 ( 1 , 9 ) and  602 ( 1 , 10 ). 
     Traces  604  for pads  602  in the third and the fourth rows mirror the configuration of traces  604  for pads  602  in the second and the first rows. 
       FIG. 7  illustrates in phantom the placement of junctions  102  (only eight are labeled) in LED die  100  on pads  602  (only one is labeled) of metalized substrate  600  in some examples of the present disclosure. In this configuration, each junction  102  connects to a different pair of pads  602 . A dashed line indicates junctions  102  with a first type of wavelength converters  118  that emits a first color of light, and a dashed-double dotted line indicates junctions  102  with a second type of wavelength converters  118  that emits a second color of light. One or more junctions  102  that have the same type of wavelength converters  118  form a segment in LED die  100 . Junctions  102  from different segments (colors) intersperse with each other in a regular pattern, such as in a checkerboard pattern (as shown), serpentine segments that spiral outward and encircle each other, or concentric circular segments. Junctions  102  from different segments may also intersperse randomly. 
       FIG. 8  is a top view of a metalized substrate  800  in some example of the present disclosure. Metalized substrate  800  may be metalized substrate  202  in package  300  ( FIG. 3 ). Metalized substrate  800  is a multi-layer tile. Metalized substrate  800  includes a 2 by 6 array of top pads  802  and traces  804 - 1 ,  804 - 2 , . . . , and  804 - 8  (collectively “traces  804 ”) connected to top pads  802 . Traces  804  fan out to the perimeter of the metalized substrate. To help understand the layout of metalized substrate  800 , a specific pad is identified by its row and column numbers. Cardinal directions are also used to describe the paths of the top traces  804 . 
     In the first row of pads  802 , a top trace  804 - 1  fans out from pad  802 ( 1 , 1 ) and travels to the north toward the perimeter of metalized substrate  800 . A top trace  804 - 2  has a diagonal portion that connects pads  802 ( 1 , 2 ) and  802 ( 2 , 3 ), and a straight portion extending from the diagonal portion to the north toward the perimeter of metalized substrate  800 . A top trace  804 - 3  has a diagonal portion that connects pads  802 ( 2 , 4 ) and  802 ( 1 , 5 ), and a straight portion extending from the diagonal portion to the north toward the perimeter of metalized substrate  800 . A top trace  804 - 4  fans out from pad  802 ( 1 , 6 ) and travels to the north toward the perimeter of metalized substrate  800 . 
     In the second row of pads  802 , a top trace  804 - 5  fans out from pad  802 ( 2 , 1 ) and travels to the south toward the perimeter of metalized substrate  800 . A lower level trace  804 - 6  has a diagonal portion that connects pads  802 ( 2 , 2 ) and  802 ( 1 , 3 ), and a straight portion extending from the diagonal portion to the south toward the perimeter of metalized substrate  800 . A lower level trace  804 - 7  has a diagonal portion that connects pads  802 ( 1 , 4 ) and  802 ( 2 , 5 ), and a straight portion extending from the diagonal portion to the south toward the perimeter of metalized substrate  800 . A top trace  804 - 8  fans out from pad  802 ( 2 , 6 ) and travels to the south toward the perimeter of metalized substrate  800 . 
       FIG. 9  illustrates in phantom the placement of junctions  102 - 1 ,  102 - 2 , . . . , and  102 - 6  in a LED die  100  on pads  802  (only one is labeled) of metalized substrate  800  in some examples of the present disclosure. In this configuration, each junction  102  connects to a different pair of pads  802 . A dashed line indicates junctions  102 - 1 ,  102 - 3 , and  102 - 5  have a first type of wavelength converters  118  that emits a first color of light, and a dashed-double dotted line indicates junctions  102 - 2 ,  102 - 4 , and  102 - 6  have a second type of wavelength converters  118  that emits a second color of light. Junctions  102 - 1 ,  102 - 3 , and  102 - 5  form a first segment in LED die  100  where the junctions connect in series. Junctions  102 - 2 ,  102 - 4 , and  102 - 6  form a second segment in LED die  100  where the junctions connect in series. Junctions  102  from different segments (colors) intersperse with each other in a regular pattern, such as in a checkerboard pattern (as shown), serpentine segments that spiral outward and encircle each other, or concentric circular segments. Junctions  102  from different segments may also intersperse randomly. Any junction  102  mounted on a pair of pads  802  in a segment may be bypassed by shorting the two traces  804  connected to the two pads  802 . For example, when junction  102 - 5  in the first segment is to be bypassed, traces  804 - 2  and  804 - 3  connected to pads  802 ( 2 , 3 ) and  802 ( 2 , 4 ) may be shorted by an external switch (shown in phantom). 
       FIG. 10  is a cross-sectional view of LED die  1000  in some examples of the present disclosure. LED die  1000  is similar to LED die  100  ( FIG. 1-2 ) but its junctions  102  share a common cathode  1014 , which takes the place of one junction  102  in the LED die  1000 . In LED die  1000 , trenches  1006  surround junctions  102 . Trenches  1006  reach down to an n-type semiconductor layer  1010  so junctions  102  are only partially electrically insulated from each other as they share a continuous n-type semiconductor layer  1010 . In this configuration, all junctions  102  are devoid of cathodes  114  ( FIG. 1-2 ). 
       FIG. 11  is a cross-sectional view of LED die  1100  in some examples of the present disclosure. LED die  1100  is similar to LED die  100  ( FIG. 1-2 ) except its junctions  102  share a common anode  1116 , which takes the place of one junction  102  in the LED die  1100 . In LED die  1100 , trenches are formed around each junction&#39;s n-type semiconductor layer  110  and active region  108 . An insulator  1106  fills these trenches before a continuous p-type semiconductor layer  1112  is formed. Junctions  102  are only partially electrically insulated from each other as they share p-type semiconductor layer  1112 . In this configuration, all junctions  102  are devoid of anodes  116  ( FIG. 1-2 ). 
       FIG. 12  illustrates in phantom the placement of junctions  102  (only one is labeled) in a LED die  1000  ( FIG. 10 ) or  1100  ( FIG. 11 ) on pads  402  (only one is labelled) of metalized substrate  400  in some examples of the present disclosure. In this configuration, each junction  102 &#39;s anode  116  or cathode  114  ( FIG. 10 or 11 ) connects to a different pad  402 , and common cathode  1014  or common anode  1116  ( FIG. 10 or 11 ) connects to one pad  402 . A dashed line indicates junctions  102  with a first type of wavelength converters  118  that emits a first color of light, and a dashed-double dotted line indicates junctions  102  with a second type of wavelength converters  118  that emits a second color of light. One or more junctions  102  that have the same type of wavelength converters  118  form a segment in LED die  1000  or  1100 . Junctions  102  from different segments (colors) intersperse with each other in a regular pattern, such as in a checkerboard pattern (as shown), serpentine segments that spiral outward and encircle each other, or concentric circular segments. Junctions  102  from different segments may also intersperse randomly. 
     To help understand the layout of the two serpentine segments, a specific junction  102  is identified by its row and column numbers. Junctions  102  in a first segment (color) may include junctions  102 ( 3 , 4 ), ( 3 , 5 ), ( 4 , 5 ), ( 5 , 5 ), ( 5 , 4 ), ( 5 , 3 ), ( 5 , 2 ), ( 4 , 2 ), ( 3 , 2 ), ( 2 , 2 ), ( 1 , 2 ), ( 1 , 3 ), ( 1 , 4 ), ( 1 , 5 ), ( 1 , 6 ), ( 1 , 7 ), ( 2 , 7 ), ( 3 , 7 ), ( 4 , 7 ), and ( 5 , 7 ). Junctions  102  in a second segment (color) may be made up of the remaining junctions  102 . 
       FIG. 13  illustrates in phantom the placement of junctions  102  (only one is labeled) in a LED die  1000  ( FIG. 10 ) or  1100  ( FIG. 11 ) on pads  602  (only one is labeled) of metalized substrate  600  in some examples of the present disclosure. In this configuration, each junction  102 &#39;s anode  116  or cathode  114  ( FIG. 10 or 11 ) connects to a different pad  602 , and common cathode  1014  or common anode  1116  ( FIG. 10 or 11 ) connects to one pad  602 . A dashed line indicates junctions  102  with a first type of wavelength converters  118  that emits a first color of light, and a dashed-double dotted line indicates junctions  102  with a second type of wavelength converters  118  that emits a second color of light. One or more junctions  102  that have the same type of wavelength converters  118  form a segment in LED die  1000  or  1100 . Junctions  102  from different segments (colors) intersperse with each other in a regular pattern, such as in a checkerboard pattern (as shown), serpentine segments that spiral outward and encircle each other, or concentric circular segments. Junctions  102  from different segments may also intersperse randomly. 
       FIG. 14  illustrates a pattern  1400  of transparent conductors on growth substrate  104 , such as a sapphire substrate, for forming wavelength converters  118  ( FIG. 1-2 ) using electrophoretic deposition (EPD) in some examples of the present disclosure. The transparent conductors may be antimony tin oxide (ATO), indium tin oxide (ITO), or silver nanowire. The transparent conductors include blocks  1402  and diagonal lines  1404 . Each block  1402  is located over a different junction  102  (only two are shown in phantom) in LED die  100 ,  1000 , or  1100  ( FIG. 1-2, 10 , or  11 ). Although shown as squares, blocks  1402  may be other shapes such as rectangles, circles, and ovals. Each block  1402  is separated from its neighboring blocks  1402  by a gap  1406  in the horizontal direction and a gap  1408  in the vertical direction. Lines  1404  connect blocks  1402  to form strings of serially connected blocks  1402 , such as diagonal strings in pattern  1400 . Anti-shock or insulating layers may be deposited between junctions  102  prior to high voltage EPD. 
       FIG. 15-1  illustrates another pattern  1500  of transparent conductors on growth substrate  104  for forming wavelength converters  118  ( FIG. 1-2 ) using EPD in some examples of the present disclosure. Lines  1404  connect blocks  1402  to form diagonally alternating strings (every-other-junction) in pattern  1500 . 
     For illustrative purposes, assume an LED die  100  includes junctions  102  that emit blue light and wavelength converters  118  are cool-white and warm-white phosphor layers that convert blue light to cool-white and warm-white colors, respectively. In a first EPD process, a first voltage is applied to a first group of strings in pattern  1400  or  1500  and cool-white phosphors are electrophoretically deposited on the first group of strings. During the first EPD process, a second voltage is applied to a second group of strings in pattern  1400  or  1500  so cool-white phosphors are not formed on the second group of strings. To reduce the risk of electrical sparking between neighboring strings, a non-zero second voltage is applied to the second group of strings. For example, the first voltage may be 800 volts while the second voltage may be 400 volts. To create a sharp transition in amount, type, or thickness of phosphor between neighboring strings, a second voltage of the opposite polarity is applied to the second group of strings. For example, the first voltage may be 800 volts while the second voltage may be −400 volts. Alternatively, the second group of strings in pattern  1400  or  1500  is not biased but kept floating. 
     In a second EPD process, a third voltage is applied to the second group of strings and warm-white phosphors are electrophoretically deposited on the second group of strings. During this second EPD process, a fourth voltage is applied to the first group of strings so warm-white phosphors are not formed on the first group of strings. To reduce the risk of electrical sparking between neighboring strings, a non-zero fourth voltage is applied to the first group of strings. To create a sharp transition in amount, type, or thickness of phosphor between neighboring strings, a fourth voltage of the opposite polarity is applied to the first group of strings. The same or different voltages described for the first EPD process may also be used for the second EPD process. Alternatively, the first group of strings in pattern  1400  or  1500  is not biased but kept floating. Note the EPD processes may be applied on a wafer scale to multiple LED dies  100  in a device wafer or individually to discrete LED die  100  singulated from the device wafer. 
     Each phosphor layer (wavelength converter)  118  has sufficient thickness to fully or substantially convert light entering the phosphor layer  118 . The phosphor thickness is controlled by the applied voltage, applied current, or the applied duration in the EPD process. 
     The size of phosphor layers  118  may be adjusted by increasing or decreasing the size of the underlying transparent conductor blocks  1402 . The size of the transparent conductor blocks  1402  may be increased to make the footprint of phosphor layers  118  larger than the underlying junctions  102 , and the size of the transparent conductor blocks  1402  may be decreased to make the footprint of phosphor layers  118  smaller than the underlying junctions  102  as shown in  FIG. 15-2  in some examples of the present disclosure. Separation of phosphor layers  118  can be adjusted by increasing or decreasing gaps  1404  and  1406  between the underlying transparent conductor blocks  1402 . By decreasing gaps  1404  and  1406 , phosphors layers  118  of different colors may abut against each other as shown in  FIG. 15-3  in some examples of the present disclosure. By increasing gaps  1404  and  1406 , phosphors layers  118  of different colors may be separated by gaps between them. 
       FIG. 16  is an International Commission on Illumination (CIE)  1976  color chart illustrating a hypothetical color tuning range of a LED die  100  having cool-white and warm-white phosphor layers in some examples of the present disclosure. The actual color tuning range of LED die  100  may be determined by simulation or experimentation. LED die  100  theoretically produces only a cool-white color at point  1602  when the cool-white segment is turned on and the warm-white segment is turned off. LED die  100  theoretically produces only a warm-white color at point  1604  when the warm-white segment is turned on and the cool-white segment is turned off. LED die  100  produces a color along a line  1606  drawn between color endpoints  1602  and  1604  when a combination of junctions  102  in the cool-white segment and the warm-white segment are turned on. The color of the blue light emitted by the underlying junctions  102  is indicated as point  1608 . 
     It may be desired to change color endpoints  1602  and  1604  to more desirable colors by allowing blue light to leak from junctions  102  in the cool-white and the warm-white segments. To allow blue light to leak from junctions  102  in the cool-white segment, each cool-white phosphor layer  118  is made with a smaller footprint than its underlying junction  102 . The ratio of the converted area to the unconverted area, and any blue light that escapes through the cool-white phosphor layer  118  itself, determines the blue light leakage for the cool-white phosphor layer  118  and sets a new cool-white color with leaked blue light at point  1610 . Similarly, each warm-white phosphor layer  118  is made with a footprint smaller than its underlying junction  102 . The ratio of the converted area to the unconverted area, and any blue light that escapes through the warm-white phosphor layer  118  itself, determines the blue light leakage for the warm-white phosphor layer  118  and sets a new warm-white color with leaked blue light at point  1612 . 
     The actual color tuning range of LED die  100  is not between new endpoints  1610  and  1612 . This is because the actual color tuning range is reduced by crosstalk between neighboring junctions  102  caused by blue light emitted near the edge of one junction  102  entering another junction&#39;s phosphor layer  118  and converting to a different color. Thus, the actual color turning range  1614  is between a cool-white color with leaked blue light and crosstalk at point  1616  and a warm-white color with leaked blue light and crosstalk at point  1618 . Fortunately, each phosphor layer  118  only partially covers its underlying junction  102  so the phosphor layer  118  is separated from its neighboring phosphor layers  118 . This separation reduces the crosstalk between phosphor layers  118  of neighboring junctions  102  and thereby increases the actual color tuning range  1614  of LED die  100 . 
       FIGS. 17 and 18  are top and bottom views, respectively, of a metalized substrate  1700  in some example of the present disclosure, and  FIG. 19  illustrates in phantom the placement of junctions  102  (only one is labeled) of a LED die  100  ( FIG. 1-2 ) on metalized substrate  1700  in some examples of the present disclosure. Instead of mounting a LED die  100  on metalized substrate  1700 , individual junctions  102  singulated from a device wafer may be picked and placed on metalized substrate  1700 . Metalized substrate  1700  may be metalized substrate  202  in package  300  ( FIG. 3 ). Metalized substrate  1700  is a multi-layer tile. Metalized substrate  1700  is configured to connect junctions  102  of a LED die  100  in two segments, such as a cool-white segment and a warm-white segment. Each segment has its junctions  102  connected in parallel, and junctions  102  from the cool-white segment and the warm-white segment are interspersed with each other in regular pattern, such a checkerboard pattern (as shown in  FIGS. 19-1 and 19-2 ), serpentine segments that spiral outward and encircle each other, or concentric circular segments. Junctions  102  from the cool-white segment and the warm-white segment may also interspersed randomly. In other examples, a segment may be a saturated color or pure blue. For example, the two segments may be a red segment and a green segment. 
     Referring to  FIG. 17 , the top surface of metalized substrate  1700  includes a 6 by 6 array of top pads  1702  (only two are labeled), and top traces  1704 - 1 ,  1704 - 2 ,  1704 - 3 , and  1704 - 4  (collectively as “traces  1704 ”) connected to top pads  1702 . To help understand the layout of top pads  1702 , a specific pad is identified by its row and column numbers. Metalized substrate includes vias  1708 - 1 ,  1708 - 2 ,  1708 - 3 , and  1708 - 4 . Referring to  FIG. 18 , the bottom surface of metalized substrate  1700  includes bottom pads  1706 - 1 ,  1706 - 2 ,  1706 - 3 , and  1706 - 4  connected to vias  1708 - 1 ,  1708 - 2 ,  1708 - 3 , and  1708 - 4 , respectively. 
     Referring to  FIGS. 19-1 and 19-2 , trace  1704 - 1  connects to bottom pad  1706 - 1  ( FIG. 17 ) through via  1708 - 1 . Trace  1704 - 1  further connects to pads  1702 ( 1 , 1 ), ( 1 , 3 ), ( 1 , 5 ), ( 5 , 1 ), ( 4 , 2 ), ( 5 , 3 ), ( 4 , 4 ), ( 5 , 5 ), ( 4 , 6 ). With junctions  102  of a LED die  100  mounted on metalized substrate  1700 , trace  1704 - 1  connects anodes  116  of junctions  102  in a first segment in parallel to bottom (anode) pad  1706 - 1 . Junctions  102  in the first (e.g., warm-white) segment are indicated by a dashed line and have a first type of wavelength converters  118  that emits a first color of light (e.g., warm-white). 
     Trace  1704 - 3  connects to bottom pad  1706 - 3  ( FIG. 17 ) through via  1708 - 3 . Trace  1704 - 3  further connects to pads  1702 ( 6 , 1 ), ( 6 , 3 ), ( 6 , 5 ), ( 3 , 6 ), ( 3 , 4 ), ( 3 , 2 ), ( 2 , 1 ), ( 2 , 3 ), ( 2 , 5 ). With junctions  102  of a LED die  100  mounted on metalized substrate  1700 , trace  1704 - 3  connects cathodes  114  of junctions  102  in the first segment in parallel to bottom (cathode) pad  1706 - 3 . 
     Trace  1704 - 2  connects to bottom pad  1706 - 2  ( FIG. 17 ) through via  1708 - 2 . Trace  1704 - 2  further connects to pads  1702 ( 1 , 6 ), ( 1 , 4 ), ( 1 , 2 ), ( 4 , 1 ), ( 4 , 3 ), ( 4 , 6 ), ( 5 , 6 ), ( 5 , 4 ), ( 5 , 2 ). With junctions  102  of a LED die  100  mounted on metalized substrate  1700 , trace  1704 - 2  connects cathodes  114  of junctions  102  in a second segment in parallel to bottom (cathode) pad  1706 - 2 . Junctions  102  in the second (e.g., cool-white) segment are indicated by a dashed-double dotted line and have a second type of wavelength converters  118  that emits a second color of light (e.g., cool-white). 
     Trace  1704 - 4  connects to bottom pad  1706 - 4  ( FIG. 17 ) through via  1708 - 4 . Trace  1704 - 4  further connects to pads  1702 ( 6 , 2 ), ( 6 , 4 ), ( 6 , 6 ), ( 2 , 6 ), ( 3 , 5 ), ( 2 , 4 ), ( 3 , 3 ), ( 2 , 2 ), ( 3 , 1 ). With junctions  102  of a LED die  100  mounted on metalized substrate  1700 , trace  1704 - 4  connects anodes  116  of junctions  102  in the second segment in parallel to bottom (anode) pad  1706 - 4 . 
     The top surface of metalized substrate  1700  includes bias lines  1710  and  1712  connected to vias  1708 - 2  and  1708 - 3 , respectively. Bias lines  1710  and  1712  are used to bias (apply voltage to) the two segments during EPD to form wavelength converters  118 . 
     The top surface of metalized substrate  1700  may include secondary paths to bias lines  1710  and  1712  to physically reduce the total length of each string and therefore reduce total parasitic resistance. For example, a trace  1714  (shown in phantom) connects the far end of trace  1704 - 2  to bias line  1710 , and a trace  1716  (shown in phantom) connects the far end of trace  1704 - 3  to bias line  1712 . 
     Metalized substrate  1700  may include a transient-voltage-suppression (TVS) diode to each segment. For example, metalized substrate  1700  includes a TVS diode  1718  connected to bottom (anode) pad  1706 - 1  through trace  1704 - 1 , and a via  1720  that connects TVS diode  1718  to bottom (cathode) pad  1706 - 3 . Metalized substrate  1700  includes a TVS diode  1722  connected to bottom (anode) pad  1706 - 4  through trace  1704 - 4 , and a via  1724  that connects TVS diode  1722  to bottom (cathode) pad  1706 - 2 . 
       FIG. 20  illustrates electrically connected strings of a metalized substrate  2000  that is a variation of metalized substrate  1700  in some example of the present disclosure. Metalized substrate  2000  is similar to metalized substrate  1700  except top traces are changed so that each segment has three sets of junctions  102  connected in parallel. 
     In the first (e.g., warm-white) segment, a trace  2004 - 1  connects via  1708 - 1  to pads  1702 ( 1 , 1 ), ( 1 , 3 ), ( 1 , 5 ). Traces  2004 - 2  connect pad  1702 ( 2 , 1 ) to pad  1702 ( 3 , 6 ), pad  1702 ( 2 , 3 ) to pad  1702 ( 3 , 2 ), and pad  1702 ( 2 , 5 ) to pad ( 3 , 4 ). Traces  2004 - 3  connect pad  1702 ( 4 , 2 ) to pad  1702 ( 5 , 3 ), pad  1702 ( 4 , 4 ) to pad  1702 ( 5 , 5 ), and pad  1702 ( 4 , 6 ) to pad  1702 ( 5 , 1 ). A trace  2004 - 4  connects pads  1702 ( 6 , 1 ), ( 6 , 3 ), and ( 6 , 5 ) to via  1708 - 3 . 
     With junctions  102  in a LED die  100  mounted on metalized substrate  2000 , traces  2004  connect three (3) sets of junctions  102  in parallel between vias  1708 - 1  and  1708 - 3 . The first set includes junctions  102  mounted on a pair of pads  1702 ( 1 , 1 ) and ( 2 , 1 ), a pair of pads  1702 ( 3 , 6 ) and ( 4 , 6 ), and a pair of pads  1702 ( 5 , 1 ) and ( 6 , 1 ). The second set includes junctions  102  mounted on a pair of pads  1702 ( 1 , 3 ) and ( 2 , 3 ), a pair of pads  1702 ( 3 , 2 ) and ( 4 , 2 ), and a pair of pads  1702 ( 5 , 3 ) and ( 6 , 3 ). The third set includes junctions  102  mounted on a pair of pads  1702 ( 1 , 5 ) and ( 2 , 5 ), a pair of pads  1702 ( 3 , 4 ) and ( 4 , 4 ), and a pair of pads  1702 ( 5 , 5 ) and ( 6 , 5 ). 
     In the second (e.g., cool-white) segment, a trace  2006 - 1  connects via  1708 - 4  to pads  1702 ( 6 , 2 ), ( 6 , 4 ), ( 6 , 6 ). Traces  2006 - 2  connect pad  1702 ( 5 , 2 ) to pad  1702 ( 4 , 1 ), pad  1702 ( 5 , 4 ) to pad  1702 ( 4 , 3 ), and pad  1702 ( 5 , 6 ) to pad ( 4 , 5 ). Traces  2006 - 3  connect pad  1702 ( 3 , 1 ) to pad  1702 ( 2 , 2 ), pad  1702 ( 3 , 3 ) to pad  1702 ( 2 , 4 ), and pad  1702 ( 3 , 5 ) to pad  1702 ( 2 , 6 ). A trace  2006 - 4  connects pads  1702 ( 1 , 2 ), ( 1 , 4 ), and ( 1 , 6 ) to via  1708 - 2 . 
     With junctions  102  in a LED die  100  mounted on metalized substrate  2000 , traces  2006  connect three (3) sets of junctions  102  in parallel between vias  1708 - 4  and  1708 - 2 . The first set includes junctions  102  mounted on a pair of pads  1702 ( 6 , 2 ) and ( 5 , 2 ), a pair of pads  1702 ( 4 , 1 ) and ( 3 , 1 ), and a pair of pads  1702 ( 2 , 2 ) and ( 1 , 2 ). The second set includes junctions  102  mounted on a pair of pads  1702 ( 6 , 4 ) and ( 5 , 4 ), a pair of pads  1702 ( 4 , 3 ) and ( 3 , 3 ), and a pair of pads  1702 ( 2 , 4 ) and ( 1 , 4 ). The third set includes junctions  102  mounted on a pair of pads  1702 ( 6 , 6 ) and ( 5 , 6 ), a pair of pads  1702 ( 4 , 5 ) and ( 3 , 5 ), and a pair of pads  1702 ( 2 , 6 ) and ( 1 , 6 ). 
     For illustrative purposes, assume growth substrate  104  has been removed from junctions  102  of a LED die  100  mounted on metalized substrate  1700  or  2000 , and cool-white phosphor layers and warm-white phosphor layers are to be formed on junctions  102  using EPD. In a first EPD process, a first voltage is applied to the warm-white segment through via  1708 - 1  and warm-white phosphors are electrophoretically deposited on junctions  102  of the warm-white segment. During the first EPD process, a second voltage is applied to the cool-white segment through via  1708 - 4  so warm-white phosphors are not formed on junctions  102  of the cool-white segment. To reduce the risk of electrical sparking between neighboring strings, a non-zero second voltage is applied to the cool-white segment. For example, the first voltage may be 800 volts while the second voltage may be 400 volts. To create a sharp transition in amount, type, or thickness of phosphor between the two segments, a second voltage of the opposite polarity is applied to the cool-white segment. For example, the first voltage may be 800 volts while the second voltage may be −400 volts. Alternatively, the cool-white segment is not biased but kept floating. 
     In a second EPD process, a third voltage is applied to the cool-white segment through via  1708 - 4  and cool-white phosphors are electrophoretically deposited on junctions  102  of the cool-white segment. During this second EPD process, a fourth voltage is applied to the warm-white segment through via  1708 - 1  so cool-white phosphors are not formed on junctions  102  of the warm-white segment. To reduce the risk of electrical sparking between neighboring strings, a non-zero fourth voltage is applied to the warm-white segment. To create a sharp transition in amount, type, or thickness of phosphor between the two segments, a fourth voltage of the opposite polarity is applied to the warm-white segment. The same voltages described for the first EPD process may also be used for the second EPD process. Alternatively, the warm-white segment is not biased but kept floating. 
       FIG. 21  is a flowchart of a method  2100  for making light-emitting device package  300  in examples of the present disclosure. Method  2100  may begin in block  2102 . 
     In block  2102 , a LED die is provided. The LED die includes junctions. The LED die may be LED die  100 ,  1000 , or  1100  ( FIG. 1-2, 10 , or  11 ). The LED die may include wavelength converters on its growth substrate over its junctions. Block  2102  is followed by block  2104 . 
     In block  2104 , a metalized substrate is provided. The metalized substrate has pads and traces connected to the pads. The metalized substrate may be metalized substrate  400 ,  600 ,  800 ,  1700 , or  2000  ( FIG. 4, 6, 8, 17 , or  20 ). Block  2104  may be followed by block  2106 . 
     In block  2106 , the LED die is mounted on the metalized substrate. For example, the junctions are mounted on the pads of the metalized substrate to create individually addressable segments. Each segment has one or more junctions. If wavelength converters are not present in the LED die, they are formed on the growth substrate of the LED die after the LED die is mounted on the metalized substrate. Alternatively, the growth substrate of the LED die is removed and the wavelength converters are formed on the junctions in the LED die. Block  2106  may be followed by block  2108 . 
     In block  2108 , a primary optic is mounted over the LED die. 
       FIG. 22  is a flowchart of a method  2200  for making a LED die in examples of the present disclosure. Method  2200  may begin in block  2202 . 
     In block  2202 , junctions are formed that are at least partially electrically insulated from each other. Block  2202  may be followed by block  2204 . 
     In block  2204 , wavelength converters are formed. Each wavelength converter is located over a different junction and separated by a gap from neighboring wavelength converters. 
     The devices described above may be used in any suitable application, such as general lighting, backlighting, or specialized lighting applications.  FIG. 23  shows a system  2300  in some examples of the present disclosure. System  2300  includes a package  300  mounted on a printed circuit board (PCB)  2302 . Package  300  has traces to its junctions connected by PCB traces to one or more drivers  2304  and  2306  on the PCB  2302 , which are controlled by a microcontroller  2308 . System  2300  may be part of a headlight assembly  2310  of a motor vehicle  2312  where the headlight assembly  2310  is capable of beam steering, spot reduction, highlighting and dynamic effect features. For a color changing package  300 , system  2300  may be part of a flash  2314  for a camera  2316  in a mobile phone  2318  where the flash  2314  is capable of color adjustment. 
     The devices described above may be light emitting pixel arrays that support applications benefitting 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. The light emitting pixel 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 at a pixel, pixel block, or device level. An example light emitting pixel array may include a device having a commonly controlled central block of high intensity pixels with an associated common optic, whereas edge pixels may have individual optics. Common applications supported by light emitting pixel arrays include camera flashes, automotive headlights, architectural and area illumination, street lighting, and informational displays. 
     A light emitting pixel array may be well suited for camera flash applications for mobile devices. Typically, an intense brief flash of light from a high intensity LED is 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 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 pixels of the light emitting pixel array are spectrally distinct, color temperature of the flash lighting may be dynamically adjusted to provide wanted color tones or warmth. 
     Automotive headlights that actively illuminate only selected sections of a roadway are also supported by light emitting pixel arrays. Using infrared cameras as sensors, light emitting pixel arrays activate only those pixels needed to illuminate the roadway while deactivating pixels 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 pixels of the light emitting pixel array are spectrally distinct, the color temperature of the light may be adjusted according to respective daylight, twilight, or night conditions. Some pixels may be used for optical wireless vehicle to vehicle communication. 
     Architectural and area illumination may also benefit from light emitting pixel arrays. Light emitting pixel arrays may be used to selectively and adaptively illuminate buildings or areas for improved visual display or to reduce lighting costs. In addition, light emitting pixel 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 pixels 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 light emitting pixel arrays. A single type of light emitting 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 pixels. 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 pixels of the light emitting pixel array are spectrally distinct, the color temperature of the light may be adjusted according to respective daylight, twilight, or night conditions. 
     Light emitting 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 light emitting arrays. This allows, for example, color changing or flashing exit signs to be projected. If a light emitting array is composed of a large number of pixels, textual or numerical information may be presented. Directional arrows or similar indicators may also be provided. 
     Various other adaptations and combinations of features of the embodiments disclosed are within the scope of the invention. Numerous embodiments are encompassed by the following claims.