Patent Publication Number: US-2022223102-A1

Title: Apparatus, methods, and articles of manufacture for a micro-led display

Description:
FIELD OF THE DISCLOSURE 
     This disclosure relates generally to micro-LEDs and, more particularly, to apparatus, methods, and articles of manufacture for a micro-LED display. 
     BACKGROUND 
     In recent years, micro-LED (micro-light emitting diode) display technology has been the focus of considerable research and development. Among other advantages, micro-LED displays show promise of consuming three to five times less power than OLED (organic LED) displays. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a known micro-LED display including an array of known pixel devices. 
         FIG. 2  is a side view of the known pixel device of  FIG. 1 . 
         FIG. 3A  illustrates a top view of an example micro-LED display in accordance with teachings of this disclosure. 
         FIG. 3B  illustrates a bottom view of the example micro-LED display of  FIG. 3A   
         FIG. 4  illustrates a side view of an example micro-LED assembly that can be implemented in the micro-LED display of  FIGS. 3A and/or 3B . 
         FIG. 5  illustrates an example sacrificial layer coupled to an example glass substrate. 
         FIG. 6  illustrates an example substrate coupled to the example sacrificial layer of  FIG. 5 . 
         FIG. 7  illustrates example bonding material deposited on first example contact pads of  FIG. 6 . 
         FIG. 8  illustrates example micro-LEDs coupled to the example first contact pads of  FIG. 7 . 
         FIG. 9  illustrates an example package resin layer provided on a first surface of the example substrate of  FIG. 8 . 
         FIG. 10  illustrates an example carrier substrate coupled to the example package resin layer of  FIG. 9 . 
         FIG. 11  illustrates the example glass substrate removed from the example substrate of  FIG. 10 . 
         FIG. 12  illustrates removal of the example sacrificial layer from the example substrate of  FIG. 11 . 
         FIG. 13  illustrates example bonding material coupled to a second surface of the example substrate of  FIG. 12 . 
         FIG. 14  illustrates a first example matrix driver coupled to the example bonding material of  FIG. 13 . 
         FIG. 15  illustrates the example micro-LED assembly of  FIG. 3  including an example cover glass coupled thereto. 
         FIG. 16  illustrates a second example micro-LED assembly that can be implemented in an example micro-LED display in addition to or instead of the example micro-LED assembly of  FIG. 3 . 
         FIG. 17  illustrates a third example micro-LED assembly that can be implemented in an example micro-LED display in addition to or instead of the micro-LED assembly of  FIG. 3  and/or the second micro-LED assembly of  FIG. 16 . 
         FIG. 18  is a flowchart representative of an example method of manufacturing the example micro-LED assembly of  FIGS. 3 and/or 15 , the second example micro-LED assembly of  FIG. 16 , and/or the third example micro-LED assembly of  FIG. 17 . 
         FIG. 19  is a flowchart representative of a first example method of electrically coupling one or more driver circuits to the example micro-LEDs in connection with block  1816  of  FIG. 18 . 
         FIG. 20  is a flowchart representative of a second example method of electrically coupling one or more driver circuits to the example micro-LEDs in connection with block  1816  of  FIG. 18 . 
     
    
    
     In general, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts. The figures are not necessarily to scale. Instead, the thickness of the layers or regions may be enlarged in the drawings. Although the figures show layers and regions with clean lines and boundaries, some or all of these lines and/or boundaries may be idealized. In reality, the boundaries and/or lines may be unobservable, blended, and/or irregular. 
     As used herein, unless otherwise stated, the term “above” describes the relationship of two parts relative to Earth. A first part is above a second part, if the second part has at least one part between Earth and the first part. Likewise, as used herein, a first part is “below” a second part when the first part is closer to the Earth than the second part. As noted above, a first part can be above or below a second part with one or more of: other parts therebetween, without other parts therebetween, with the first and second parts touching, or without the first and second parts being in direct contact with one another. 
     Notwithstanding the foregoing, in the case of a semiconductor device, “above” is not with reference to Earth, but instead is with reference to a bulk region of a base semiconductor substrate (e.g., a semiconductor wafer) on which components of an integrated circuit are formed. Specifically, as used herein, a first component of an integrated circuit is “above” a second component when the first component is farther away from the bulk region of the semiconductor substrate than the second component. 
     As used in this patent, stating that any part (e.g., a layer, film, area, region, or plate) is in any way on (e.g., positioned on, located on, disposed on, or formed on, etc.) another part, indicates that the referenced part is either in contact with the other part, or that the referenced part is above the other part with one or more intermediate part(s) located therebetween. 
     As used herein, connection references (e.g., attached, coupled, connected, and joined) may include intermediate members between the elements referenced by the connection reference and/or relative movement between those elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and/or in fixed relation to each other. As used herein, stating that any part is in “contact” with another part is defined to mean that there is no intermediate part between the two parts. 
     Unless specifically stated otherwise, descriptors such as “first,” “second,” “third,” etc., are used herein without imputing or otherwise indicating any meaning of priority, physical order, arrangement in a list, and/or ordering in any way, but are merely used as labels and/or arbitrary names to distinguish elements for ease of understanding the disclosed examples. In some examples, the descriptor “first” may be used to refer to an element in the detailed description, while the same element may be referred to in a claim with a different descriptor such as “second” or “third.” In such instances, it should be understood that such descriptors are used merely for identifying those elements distinctly that might, for example, otherwise share a same name. 
     As used herein, “approximately” and “about” refer to dimensions that may not be exact due to manufacturing tolerances and/or other real world imperfections. As used herein “substantially real time” refers to occurrence in a near instantaneous manner recognizing there may be real world delays for computing time, transmission, etc. Thus, unless otherwise specified, “substantially real time” refers to real time+/−1 second. 
     DETAILED DESCRIPTION 
     Micro-LED displays produce light in response to current flowing through individual micro-LEDs of the display. Micro-LEDs include inorganic structures with typical “on” voltage drops ranging from 1.9 volts (V) to 3 V depending on a color displayed. In some instances, micro-LEDs are arranged in a two-dimensional array (e.g., matrix) of elements to provide a display. Unlike organic LEDs (OLEDs), micro-LEDs utilize inorganic compounds (e.g., gallium nitride) that are illuminated when supplied with current as opposed to organic compounds used in OLED displays. As used herein, the term “micro-LED” is not limited to a specific LED dimension. However, in some examples, the micro-LEDs have a dimension (e.g., a length and/or a width) that is less than 100 micrometers. For example, a size of the micro-LEDs can be less than or equal to 100 micrometers by 100 micrometers. In some examples, the size of the micro-LEDs can be less than or equal to 30 micrometers by 30 micrometers. 
     Active-matrix micro-LED displays provide high-resolution color graphics with a high refresh rate. In some examples, the display includes at least M×N pixel devices in a matrix having M rows and N columns, including at least one of the M×N pixel devices positioned at each matrix junction where a row intersects a column. Each of the M×N pixel devices includes one or more LEDs and a pixel driver circuit to control the one or more LEDs. In some examples, each of the M×N pixel devices corresponds to an individual element (e.g., a pixel) on a substrate of the display. 
     Typically, at least one row driver and at least one column driver are used to control individual ones of the pixel devices located at the matrix junctions. For example, the column drivers drive the columns (connected to device anodes) and the row drivers drive the rows (connected to device cathodes). In some examples, the row drivers sequentially scan the rows with a driver switch to a known voltage such as a ground. In operation, information is transferred to the display by scanning each row in sequence. During each row scan period, the column drivers also drive each column in the current row that is connected to an element intended to emit light. 
     Typical pixel devices conduct current and luminesce (e.g., emit light) when voltage of one polarity is imposed across the pixel devices, and block current when voltage of an opposite polarity is applied. To produce the perception of a grayscale or a full-color image using a micro-LED display at optimal power efficiency, it is necessary to rapidly modulate micro-LEDs of pixel devices of the display between on and off states such that the average of their modulated brightness waveforms correspond to a desired ‘analog’ brightness for each pixel. This technique is generally referred to as pulse-width modulation (PWM). Above a particular modulation frequency, the human eye and brain integrate a pixel&#39;s rapidly varying brightness (and color, in a field-sequential color display) and perceive a brightness (and color) determined by the pixel&#39;s average illumination over a period of time (e.g., over a display of a video frame). 
     PWM operation of micro-LEDs provides improvements in power efficiency when compared to analog driving. However, driving micro-LEDs using pulses of a PWM signal sent from column drivers across display lengths can cause undesired high power consumption and pulse distortion. To address some drawbacks of PWM signals, some micro-LED devices include PWM circuits to control each pixel device. Such PWM circuits may be implemented in a silicon (Si) complementary metal-oxide-semiconductor (CMOS) and transferred to a backplane on the same surface as the micro-LEDs. While this technique may work for large displays that include large pixels (e.g., televisions), as pixel size decreases, such techniques become infeasible to make small enough for products such as laptops and smartphones due to a transistor count of the circuits when implemented with thin-film transistor (TFT) technology. Furthermore, by implementing the PWM circuits on the same surface as the micro-LEDs, known micro-LED devices limit a resolution of a micro-LED display by limiting pixel pitch reduction of the micro-LED display. In particular, the surfaces of the micro-LED devices are sized to accommodate at least the micro-LEDs and the corresponding PWM circuits thereupon, such that a distance between adjacent pixels (e.g., the pixel pitch) is unable to be reduced less than a threshold distance. Additionally, by requiring a large number of the PWM circuits (e.g., one of the PWM circuits per pixel), known micro-LED displays have high manufacturing complexity and parts costs. 
     As used herein, “pixels” refer to discrete controllable elements of a micro-LED display, where each pixel includes a corresponding cluster of micro-LEDs (e.g., a red micro-LED, a green micro-LED, and a blue micro-LED). As used herein, “pixel pitch” refers to the distance between adjacent pixels in a micro-LED display. As used herein, a “pixel density” and/or “resolution” of the micro-LED display increases when the pixel pitch decreases, and the pixel density and/or the resolution decreases when the pixel pitch increases. 
     Examples disclosed herein enable a reduction in pixel pitch (e.g., an increase in pixel density) of a micro-LED display by providing a micro-LED array (e.g., matrix) of micro-LEDs on a first side of a substrate (e.g., a polyimide substrate) and corresponding drivers (e.g., matrix driver circuits and/or assist driver circuits) on a second side of the substrate opposite the first side. In examples disclosed herein, conductive paths in the substrate electrically couple the micro-LEDs of the micro-LED array to the corresponding drivers. In some examples, etching, laser removal, and/or polishing of the second side of the substrate is used to expose the conductive paths, thus exposing contact pads on the second side. In some examples, each of the matrix driver circuits is to control multiple ones of the micro-LEDs. Advantageously, examples disclosed herein reduce a number of drivers to be implemented in a micro-LED display, thus reducing parts costs for the display. Additionally, examples disclosed herein enable an increase in pixels per inch (PPI) of the display by reducing the pitch between the individual pixels, thus improving a resolution of the display. 
       FIG. 1  illustrates a known micro-LED display  100  including a micro-LED array  102 . In some instances, the known micro-LED display  100  can be implemented on an electronic device such as a laptop, a tablet, a smartphone, a smartwatch, a television, a computer monitor, etc. In  FIG. 1 , the micro-LED array  102  includes known pixel devices  104  arranged in a two-dimensional matrix on an active area  106  of a panel (e.g., a micro-LED panel)  108 . In  FIG. 1 , each of the known pixel devices  104  corresponds to an individual pixel of the known micro-LED display  100 . While reference is made to one of the known pixel devices  104 , description and/or illustration associated with the one of the known pixel devices  104  can be considered to apply equally to each of the known pixel devices  104  of  FIG. 1 . 
     In  FIG. 1 , each of the known pixel devices  104  includes one or more micro-LEDs  110 . For instance, the known known pixel device  104  in  FIG. 1  includes a first micro-LED  110 A, a second micro-LED  110 B, and a third micro-LED  110 C on a surface of the known pixel device  104 . In some instances, the different micro-LEDs  110  on the known pixel device  104  correspond to different colored lights. For instance, the first, second, and third micro-LEDs  110 A,  110 B,  110 C of  FIG. 1  correspond to red, green, and blue colored lights, respectively. As illustrated in  FIG. 1 , each of the known pixel devices  104  further includes a known pixel driver  116  on the same surface of the known pixel devices  104  as the micro-LEDs  110 . The known pixel driver  116  is electrically coupled to each of the micro-LEDs  110  to control operation thereof. For instance, the known pixel driver  116  can control a signal (e.g., a current) provided to ones of the micro-LEDs  110 , where the signal can be used to turn on the ones of the micro-LEDs  110  and/or vary a brightness thereof. As represented in  FIG. 1 , each known pixel device  104  has a separate known pixel driver  116  to control the micro-LEDs  110  on each corresponding known pixel device  104 . In some instances, the known pixel driver  116  corresponds to a self-contained integrated circuit (IC) chip mounted to the surface of the known pixel device  104 . 
     As shown in  FIG. 1 , the known micro-LED display  100  includes row drivers (e.g., row driver circuits)  118  and column drivers (e.g., column driver circuits)  120  on the panel  108  outside of the active area  106 . In some instances, the known pixel drivers  116  are driven by the column drivers  120  and the row drivers  118 . For instance, the column drivers  120  supply a low frequency signal (e.g., a sawtooth wave signal, a triangular/triangle wave signal, etc.) while the row drivers  118  supply a scan signal to selectively pass a data signal representative of an image to be displayed to activate the micro-LEDs  110  of the known pixel devices  104  of a particular row of the known micro-LED display  100 . The data signal may be supplied to the known micro-LED display  100  from a digital-to-analog converter (DAC) to drive the known micro-LED display  100  to display an image initially represented in digital data. The known pixel drivers  116  convert the low frequency signal into a higher frequency PWM signal having a pulse that is based on the DC voltage of the input data signal. In some instances, the amplitude of the PWM signal is fixed at a level that drives the micro-LEDs  110  at efficient operating current while the pulse width of the PWM signal controls the brightness and/or color of the micro-LEDs  110 . While four of the row drivers  118  and four of the column drivers  120  are shown in the illustrated example of  FIG. 1 , a different number of the row drivers  118  and/or the column drivers  120  may be used instead. 
       FIG. 2  is a side view of the known pixel device  104  of  FIG. 1 . As shown in  FIG. 2 , the known pixel driver  116  and the micro-LED(s)  110  are coupled to a top surface  202  of an example substrate  204  of the known pixel device  104 . In some instances, a surface area of the top surface  202  is sized to accommodate placement of the known pixel driver  116  and the micro-LED(s)  110  thereupon. In some instances, increasing a resolution (e.g., pixel count) of the known micro-LED display  100  of  FIG. 1  requires a reduction in size of the known pixel devices  104 . However, such reduction in size may not be feasible when the known pixel driver  116  and the micro-LED(s)  110  are implemented on the top surface  202  as shown in  FIGS. 1 and 2 . 
       FIGS. 3A and 3B  illustrate a top view and a bottom view, respectively, of an example micro-LED display  300  constructed in accordance with teachings disclosed herein. Unlike the known micro-LED display  100  of  FIG. 1 , the example micro-LED display  300  of  FIG. 3A  implements example pixel devices  302  in an M×N array in an example active area  304  of an example panel  306  of the micro-LED display  300 . In the illustrated example of  FIG. 3A , similar to the known pixel devices  104  of  FIG. 1 , each of the pixel devices  302  of  FIG. 3A  corresponds to an individual pixel of the micro-LED display  300  of  FIG. 3 . Furthermore, each of the pixel device  302  of  FIG. 3A  includes three of micro-LEDs  110 , including a first micro-LED  110 A corresponding to a red colored light, a second micro-LED  110 B corresponding to a green colored light, and a third micro-LED  110 C corresponding to a blue colored light. However, in contrast to the known pixel devices  104  of the micro-LED display  100  of  FIG. 1 , the example pixel devices  302  of  FIG. 3  do not include the known pixel drivers  116  on a top surface of the pixel devices  302  (e.g., adjacent the micro-LEDs  110 ). 
     Instead, as shown in the illustrated example of  FIG. 3B , example matrix drivers (e.g., matrix driver circuits, IC chips)  320  are on a bottom surface of the pixel devices  302  opposite the top surface on which the micro-LEDs  110  are positioned. In this example, each of the matrix drivers  320  is electrically and/or operatively coupled to corresponding ones of the pixel devices  302 . For example, each of the matrix drivers  320  is to control an m×n submatrix of the pixel devices  302 , where, in this example, m is less than M total rows of the pixel devices  302  and n is less than N total columns of the pixel devices  302 . In the illustrated example of  FIG. 3B , each of the matrix drivers  320  controls a sixteen of the pixel devices (e.g., a corresponding 4×4 submatrix of the pixel devices  302 ). In other examples, the matrix drivers  320  can control a different number of the pixel devices  302  (e.g., 100, 1,000, etc.) in corresponding regions of the micro-LED display  300 . In particular, each of the matrix drivers  320  can control up to 100,000 of the pixel devices  302 . In this example, a size of one of the matrix drivers  320  is greater than a size of one of the pixel devices  302  (e.g., more than twice the size of the one of the pixel devices  302 ). 
     In contrast to each of the known pixel drivers  116  of  FIG. 1  controlling a corresponding one of the known pixel devices  104  of  FIG. 1 , the matrix drivers  320  of  FIG. 3B  control multiple ones of the pixel devices  302  of  FIGS. 3A and/or 3B  by providing electrical signals thereto. In this example, by enabling the matrix drivers  320  to control and/or otherwise drive multiple ones of the micro-LEDs  110  of the pixel devices  302 , a number of drivers in the micro-LED display  300  can be reduced, thus reducing parts costs associated therewith. Furthermore, by implementing the matrix drivers  320  on the bottom surface of the pixel devices  302 , a surface area of the pixel devices  302  can be reduced compared to a surface area of the known pixel devices  104  of  FIG. 1 . This, in turn, enables different pixel devices  302  to be positioned closer together, thereby increasing the resolution or pixel density (e.g., the PPI) that can be achieved when compared to the known micro-LED display  100  of  FIG. 1 . 
     In the illustrated example of  FIG. 3B , the micro-LED display  300  includes example assist driver circuits  330  coupled to the panel  306  outside the active area  304  of the micro-LED display  300 . In this example, each of the assist driver circuits  330  is electrically and/or operatively coupled to one or more of the matrix drivers  320  to send control signals thereto. In  FIG. 3B , a combination of the assist driver circuits  330  and the corresponding matrix drivers  320  are used to control the micro-LEDs  110  instead of the row drivers  118 , the column drivers  120 , and the known pixel drivers  116  of  FIG. 1 . In particular, each of the assist driver circuits  330  can control multiple rows and/or columns of the pixel devices  302 , such that the micro-LED display  300  of  FIGS. 3A and/or 3B  does not require separate drivers to control the individual rows and columns of the pixel devices  302 . 
       FIG. 4  illustrates an example micro-LED assembly  400  in accordance with teachings of this disclosure. In some examples, the micro-LED assembly  400  is used to construct the micro-LED display  300  of FIGS.  3 A and/or  3 B. For example, the micro-LED assembly  400  electrically couples ones of the micro-LEDs  110 , the matrix drivers  320 , and/or the assist driver circuits  330  via example conductive paths  402  in an example substrate  404 . In some examples, the conductive paths  402  include multiple layers of conductive material (e.g., metal) that define planes or traces of the conductive material that are separated by layers of dielectric material. The conductive material in the separate layers are electrically connected by metal vias extending through the dielectric layers in the substrate  404 . In this example, the dielectric material of the substrate  404  includes a polyimide material. In other examples, one or more different materials may be used for the substrate  404  instead. In some examples, a thickness of the substrate  404  is greater than or equal to 2 micrometers (μm) and less than or equal to 50 μm. In this example, the conductive paths  402  extend between a first side  408  and a second side  410  of the substrate  404  to enable flow of electrical signals between the first and second sides  408 ,  410 . For example, the conductive paths  402  include cross-linking paths (e.g., cross-metal signal links) that extend in X and Y directions of a plane of the substrate  404  to electrically couple different locations of the substrate  404  (e.g., to deliver control signals to select ones of the micro-LEDs  110 ). Additionally or alternatively, the conductive paths  402  can include one or more internal contact paths to couple locations internal to the substrate  404 , and/or one or more power metal mesh layers through which power can be supplied to one or more components of the micro-LED assembly  400 . In this example, the conductive paths  402  are electrically coupled with first contact pads (e.g., raised contact pads)  412  on a first surface (e.g., a top surface)  414  of the substrate  404 . The micro-LEDs  110  are electrically and mechanically coupled to the first contact pads  412  via example bonding material  416  (e.g., solder) deposited on the first contact pads  412 . In some examples, an example package resin layer  418  is provided on the first side  408  of the substrate  404  to envelop the micro-LEDs  110  and/or provide protection of the micro-LEDs  110  from external forces and/or damage. In such examples, the package resin layer  418  is a transparent material that passes light therethrough from the micro-LEDs  110 . In some examples, a refractive index of the package resin layer  418  provides a refractive index that enables a dispersion of light from the micro-LEDs  110  in multiple directions, thus improving efficiency of light emission from the micro-LEDs  110 . 
     In the illustrated example of  FIG. 3 , the micro-LED assembly  400  includes the example matrix drivers (e.g., matrix driver circuits, active matrix drivers)  320  on the second side  410  of the substrate  404 . In this example, the matrix drivers  320  include a first example matrix driver  320 A and a second example matrix driver  320 B electrically coupled to example second contact pads  424  on an example second surface (e.g., a bottom surface)  426  on the second side  310  of the substrate  404 . For example, the matrix drivers  320  are electrically coupled to the second contacts pads  424  via an example bonding material  428  coupled to the second surface  426 . In some examples, the bonding material  428  is an anisotropic conductive film. Additionally or alternatively, in some examples, the matrix drivers  320  are electrically and mechanically coupled directly to the second contact pads  424  via solder. In other examples, one or more different bonding methods to couple the matrix drivers  320  to the second contact pads  424  may be used instead. In some examples, the second contact pads  424  are electrically coupled to the first contact pads  412  and, thus, the micro-LEDs  110 , via the conductive paths  402 . As such, the conductive paths  402  electrically couple the matrix drivers  320  to corresponding ones of the micro-LEDs  110 . 
     In the illustrated example, one of the example assist driver circuits  330  on the second side  410  of the substrate  404  is electrically coupled to ones of the second contact pads  424  via the bonding material  428 . In other examples, the assist driver circuit  330  is electrically and mechanically coupled directly to ones of the second contact pads  424  via a bonding material (e.g., solder). In some examples, ones of the conductive paths  402  are further electrically coupled between different ones of the second contact pads  424  to enable transmission of signals between the assist driver circuit  330  and the matrix drivers  320 . For example, first conductive paths (e.g., a first portion of the conductive paths  402 ) are used to electrically couple the second contact pads  424  to the first contact pads  412 , and second conductive paths (e.g., a second portion of the conductive paths  402 ) are used to electrically couple different ones of the second contact pads  424  to one another. In particular, the second conductive paths of the conductive paths  402  electrically couple first ones of the second contact pads  424  to second ones of the second contact pads  424 , where the first ones of the second contact pads  424  are coupled to the matrix drivers  320 , and the second ones of the second contact pads  424  are coupled to the assist driver circuit  330 . In such examples, first signals (e.g., first electrical signals) may be provided from the matrix drivers  320  to corresponding ones of the micro-LEDs  110  via the first conductive paths to control a frequency and/or intensity of light emitted by the micro-LEDs  110 . Furthermore, second signals (e.g., second electrical signals) may be provided from the assist driver circuit  330  to the matrix drivers  320  to selectively activate or deactivate ones of the micro-LEDs  110 . 
     A process of manufacturing the micro-LED assembly  400  of  FIG. 4  is described in connection with  FIGS. 5-14  below. In particular,  FIGS. 5-14  illustrate various stages in the process of manufacturing the micro-LED assembly  400  of  FIG. 4 . 
       FIG. 5  illustrates an example sacrificial layer  502  coupled to an example glass substrate  504 . For example, to manufacture the micro-LED assembly  400  of  FIG. 4 , the sacrificial layer  502  is deposited on the glass substrate  504 . In some such examples, the sacrificial layer  502  is removably coupled to the glass substrate  504 . In some examples, the sacrificial layer  502  is a polyimide material. However, one or more different materials may be used for the sacrificial layer  502  instead. 
       FIG. 6  illustrates the example substrate  404  coupled to the sacrificial layer  502  of  FIG. 5 . For example, the example substrate  404  is deposited on the sacrificial layer  502  by depositing subsequent layers of polyimide material on the sacrificial layer  502 . That is, in some examples, the polyimide substrate  404  is an extension of the polyimide sacrificial layer  502 . In this example, during production of the substrate  404 , the example conductive paths  402  are provided within the substrate  404 . For example, conductive material is deposited with the layers of polyimide material to provide the conductive paths  402 . In some examples, the conductive paths  402  can extend in an example horizontal direction  602  and/or an example vertical direction  604  through the substrate  404 . For example, a first portion of the conductive paths  402  (e.g., first conductive paths) extend in the vertical direction  604  to the first surface  414  of the substrate  404 . In this example, the first portion of the conductive paths  402  extend to the first surface  414  and are electrically coupled to the first contact pads  412 . In some examples, the first contact pads  412  are integrally provided as part of the conductive paths  402 . In this example, the first contact pads  412  protrude from the first surface  414 . In other examples, the conductive paths  402  do not protrude from the first surface  414 , such that the first contact pads  412  are approximately level with the first surface  414  and/or below the first surface  414 . In some examples, a second portion of the conductive paths  402  (e.g., second conductive paths) extend at least partially in the horizontal direction  602  to electrically couple two or more points within the substrate  404 . 
       FIG. 7  illustrates example bonding material  416  (e.g., solder) deposited on the first contact pads  412  of  FIG. 6 . For example, to enable coupling of the micro-LEDs  110  of  FIGS. 3A and/or 4  to the first contact pads  412 , the bonding material  416  is deposited on the first contact pads  412 . In some examples, the bonding material  416  can be a conductive material (e.g., solder). 
       FIG. 8  illustrates the example micro-LEDs  110  coupled to the first contact pads  412 . In some examples, the micro-LEDs  110  are aligned with corresponding ones of the first contact pads  412 , and pressure and/or heat can be applied to the bonding material  416  to enable bonding of the micro-LEDs  110  to the first contact pads  412 . In this example, the bonding material  416  allows flow of electrical signals (e.g., current) therethrough. As such, the bonding material  416  electrically couples the micro-LEDs  110  to the first contact pads  412  and, thus, the conductive paths  402 . In this example, each of the micro-LEDs  110  is coupled to at least two of the first contact pads  412 . In such examples, a first one of the at least two of the first contact pads  412  is coupled to a cathode of a corresponding one of the micro-LEDs  110 , and a second one of the at least two of the first contact pads  412  is coupled to an anode of the corresponding one of the micro-LEDS  110 . In some examples, the micro-LEDs  110  are mass transferred onto the substrate  404  and/or the first contact pads  412 . For example, multiple ones of the micro-LEDs  110  are constructed together and transferred to the substrate  404  and/or the first contact pads  412  at substantially the same time (e.g., during a single operation) to improve speed and/or efficiency of manufacture of the micro-LED assembly  400 . 
       FIG. 9  illustrates an example package resin layer  418  provided on the first surface  412  of the example substrate  404 . For example, the package resin layer  418  can include an epoxy resin and/or silicone material. In this example, the package resin layer  418  surrounds and/or otherwise envelops the micro-LEDs  110  to protect the micro-LEDs  110  from contaminants and/or damage. In some examples, the package resin layer  418  is a transparent material that enables light emitted by the micro-LEDs  110  to pass through the package resin layer  418 . Furthermore,  FIG. 10  illustrates an example carrier substrate  1002  coupled to the package resin layer  418 . For example, the carrier substrate  1002  is removably coupled to the package resin layer  418  via an adhesive. In some examples, the carrier substrate  1002  protects the package resin layer  418  during transportation and/or installation of the micro-LED assembly  400 . In some examples, the carrier substrate  1002  is glass. 
     Turning to  FIG. 11 , the example glass substrate  504  is removed from the substrate  404 . For example, the glass substrate  504  is lifted off of and/or otherwise removed from the substrate  404  to expose the sacrificial layer  502  of the substrate  404 . Furthermore,  FIG. 12  illustrates removal of the sacrificial layer  502  from the example substrate  404 . In some examples, the sacrificial layer  502  can be removed by etching, polishing, and/or lasering of the sacrificial layer  502  until ends of the conductive paths  402  in the substrate  404  are exposed. In such examples, the exposed ends of the conductive paths  402  provide the second contact pads  424  on the second surface  426  of the substrate  404 . In some examples, the second contacts pads  424  are approximately level with the second surface  426 . Furthermore, ones of the second contact pads  424  are electrically coupled to the first contact pads  412  via the conductive paths  402  in the substrate  404 . 
       FIG. 13  illustrates the example bonding material  428  coupled to the second surface  426  of the substrate  404 . For example, the bonding material  428  is coupled to the second surface  426  and electrically coupled to each of the second contact pads  424  thereupon. In some examples, the bonding material  428  includes an anisotropic conductive film for coupling one or more drivers (e.g., the matrix drivers  320  of  FIG. 4 ) thereto. In some examples, the bonding material  428  provides a substantially smooth and/or flat surface to enable coupling of drivers (e.g., the matrix drivers  320  and/or the assist driver circuits  330 ) thereto. For example, the bonding material  428  can account for irregularities and/or non-flat surface features of the second surface  426  created during etching, polishing, and/or lasering of the substrate  404 . 
       FIG. 14  illustrates the example first matrix driver  320  coupled to the example bonding material  428 . In such examples, the matrix driver  320  is electrically coupled to ones of the second contacts pads  424  via the bonding material  428 . Accordingly, the matrix driver  320  is further electrically coupled to the conductive paths  402 , the first contact pads  412 , and, thus, the micro-LEDs  110 . In some examples, the matrix driver  320  can independently control the micro-LEDs  110  by providing electrical signals thereto via corresponding ones of the conductive paths  402 . In this example, the matrix driver  320  is a standalone IC chip that is separately fabricated using any suitable semiconductor fabrication processes before being transferred to the substrate  404  as shown in  FIG. 14 . In examples disclosed herein, multiple ones of the matrix drivers  320  can be transferred to the substrate  404  via the bonding material  428  at substantially the same time (e.g., during a single operation) to improve a speed and/or efficiency of manufacturing the micro-LED assembly  400 . 
       FIG. 15  illustrates the example micro-LED assembly  400  of  FIG. 4  including an example cover glass  1502  coupled thereto. In some examples, the cover glass  1502  corresponds to the carrier substrate  1002  of  FIG. 10 . In other examples, the carrier substrate  1002  is removed during installation of the micro-LED assembly  400  in the panel  306  of  FIGS. 3A and/or 3B , and the cover glass  1502  is coupled to the package resin layer  418  via an example adhesive layer  1504 . In some examples, the cover glass  1502  protects the package resin layer  418  and/or the micro-LEDs  110  from damage during construction, installation, and/or use of the micro-LED display  100  of  FIG. 1 . 
       FIG. 16  illustrates a second example micro-LED assembly  1600  that can be implemented in the micro-LED display  300  of  FIGS. 3A and/or 3B  in addition to or instead of the micro-LED assembly  400  of  FIG. 4 . In the illustrated example of  FIG. 16 , a first example micro-LED matrix tile  1601 A is electrically coupled to the first matrix driver  320 A, and a second example micro-LED matrix tile  1601 B is electrically coupled to the second matrix driver  322 . In this example, the first micro-LED matrix tile  1601 A includes a first example substrate  404 A and a first portion of the micro-LEDs  110 , and the second micro-LED matrix tile  1601 B includes the second substrate  404 B and a second portion of the micro-LEDs  110 . In this example, the first micro-LED matrix tile  1601 A is separate from the second micro-LED matrix tile  1601 B. In some examples, the separate micro-LED matrix tiles  1601 A,  1602 B are discrete unitary assemblies that are separately manufactured before being combined or assembled with the other components of the second micro-LED assembly  1600 . However, in other examples, the first and second substrates  304 A,  304 B can be a unitary substrate (e.g., the substrate  404  of  FIG. 4 ). 
     In the illustrated example of  FIG. 16 , the second micro-LED assembly  1600  includes an example printed circuit board (PCB)  1602  coupled between the micro-LED matrix tiles  1601 A,  1601 B and the corresponding matrix drivers  320 A,  320 B. In this example, the micro-LED matrix tiles  1601 A,  1601 B are coupled to a first example side  1604  of the PCB  1602  and the matrix drivers  320 ,  322  and the assist driver circuit  330  are coupled to a second example side  1606  of the PCB  1602 . For example, the PCB  1602  includes third example contact pads  1610  on the first side  1604  of the PCB  1602 , where the third contact pads  1610  are coupled to corresponding ones of the second contact pads  424  on the substrates  404 A,  404 B. Furthermore, the PCB  1602  includes fourth example contact pads  1612  on the second side  1606  of the PCB  1602 , where the fourth contact pads  1612  are coupled to corresponding ones of the matrix drivers  320  and/or the assist driver circuit  330 . 
     In this example, ones of the fourth contact pads  1612  are electrically coupled to the third contact pads  1610  and/or to one another via conductive traces and/or interconnects in the PCB  1602  to allow transmission of signals therebetween. As such, the PCB  1602  electrically couples the matrix drivers  320  to corresponding ones of the micro-LED matrix tiles  1601 A,  1601 B, and further electrically couples the matrix drivers  320  to the assist driver circuit  330 . In some examples, the micro-LED matrix tiles  1601 A,  1601 B are independently manufactured and mounted to the PCB  1602  (e.g., separately from the matrix drivers  320  and/or the assist driver circuits  330 ). As such, the micro-LED matrix tiles  1601 A,  1601 B can be mounted to the PCB  1602  prior to or after the mounting of the matrix drivers  320  and/or the assist driver circuits  330 . Furthermore, while two of the micro-LED matrix tiles  1601 A,  1601 B are shown in this example, a different number and/or arrangement of the micro-LED matrix tiles  1601 A,  1601 B may be used instead. 
       FIG. 17  illustrates a third example micro-LED assembly  1700  that can be implemented in the micro-LED display  300  of  FIGS. 3A and/or 3B  in addition to or instead of the micro-LED assembly  400  of  FIG. 3  and/or the second micro-LED assembly  1600  of  FIG. 16 . In the illustrated example of  FIG. 17 , a structure of the third micro-LED assembly  1700  is similar to a structure of the second micro-LED assembly  1600  of  FIG. 16 . However, unlike the second micro-LED assembly  1600  of  FIG. 16 , the third micro-LED assembly  1700  of  FIG. 17  does not include the second matrix driver  320 B. Instead, the third example micro-LED assembly  1700  of  FIG. 17  includes an example timing controller  1702  coupled to ones of the fourth contact pads  1612  of the PCB  1602 . In this example, the timing controller  1702  is electrically and/or operatively coupled to the first matrix driver  320 A and/or the assist driver circuit  330  to control a timing and/or frequency of signals transmitted to and/or from the first matrix driver  320 A and/or the assist driver circuit  330 . In this example, the first matrix driver  320 A is electrically coupled to each of the micro-LED matrix tiles  1601 A,  1601 B to independently control the micro-LEDs  110  thereof. In the illustrated example of  FIG. 17 , an example connector (e.g., a system connector)  1704  is coupled to one of the fourth contact pads  1612 . In some examples, the connector  1704  is electrically couplable to a power source of the micro-LED display  300  of  FIGS. 3A and/or 3B . 
       FIG. 18  is a flowchart representative of an example method  1800  of manufacturing the example micro-LED assembly  400  of  FIGS. 3 and/or 15 , the second example micro-LED assembly  1600  of  FIG. 16 , and/or the third example micro-LED assembly  1700  of  FIG. 17 . In some examples, some or all of the operations outlined in the example method  1800  are performed automatically by fabrication equipment that is programmed to perform the operations. Although the example method of manufacturing is described with reference to the flowchart illustrated in  FIG. 18 , many other methods may alternatively be used. For example, the order of execution of the blocks may be changed, and/or some of the blocks described may be combined, divided, re-arranged, omitted, eliminated, and/or implemented in any other way. 
     The example method  1800  of  FIG. 18  begins at block  1802  by depositing the example sacrificial layer  502  on the example glass substrate  504  of  FIG. 5 . For example, the sacrificial layer  502  is fabricated on the glass substrate  504  by depositing subsequent layers of polyimide material thereupon. 
     At block  1804 , the example method  1800  includes depositing the example substrate  404  including the conductive paths  402  on the sacrificial layer  502 . For example, the substrate  404  and the conductive paths  402  are fabricated by depositing layers of polyimide material and/or conductive material on the sacrificial layer  502 , where the conductive material corresponds to the conductive paths  402  in the substrate  404 . In some examples, additional conductive material is deposited on ends of the conductive paths  402  such that the conductive material protrudes from the first surface  312  of the substrate  404  to provide the first contact pads  412 . 
     At block  1806 , the example method  1800  includes transferring the micro-LEDs  110  to the first contact pads  412  of the first side  308  of the substrate  404 . For example, the bonding material  416  is deposited and/or fabricated on the first contact pads  412 , and the micro-LEDs  110  are positioned on corresponding ones of the first contact pads  412 . In some examples, pressure and/or heat is applied to the micro-LEDs  110  and/or the bonding material  416  to bond and/or otherwise electrically couple the micro-LEDs  110  to the first contact pads  412 . In some examples, multiple ones of the micro-LEDs  110  are transferred (e.g., mass transferred) to the first side  308  of the substrate  404  at substantially the same time. 
     At block  1808 , the example method  1800  includes depositing the package resin layer  418  on the first side  308  of the substrate  404 . For example, the package resin layer  418  is deposited on the first surface  312  of the substrate  404  to surround and/or otherwise envelop the micro-LEDs  110 . In some examples, the package resin layer  418  is a transparent material, including an epoxy and/or a silicone material. 
     At block  1810 , the example method  1800  includes coupling the carrier substrate  1002  to the package resin layer  418 . For example, the carrier substrate  1002  is coupled, via an adhesive, to the package resin layer  418  to protect and/or provide support to the micro-LED assembly  400 , the second micro-LED assembly  1600 , and/or the third micro-LED assembly  1700  during transportation and/or installation thereof. 
     At block  1812 , the example method  1800  includes removing the glass substrate  504  from the sacrificial layer  502 . For example, the glass substrate  504  is lifted off of and/or otherwise removed from the sacrificial layer  502  to expose a surface of the sacrificial layer  502 . 
     At block  1814 , the example method  1800  includes removing the sacrificial layer  502  from the substrate  404  to expose the second contact pads  424  on the second side  310  of the substrate  404 . For example, the sacrificial layer  502  is removed by etching, polishing, and/or lasering layers of the polyimide material of the sacrificial layer  502  until the second contact pads  424  are exposed. 
     At block  1816 , the example method  1800  includes electrically coupling at least one of the matrix drivers  320  to the micro-LEDs  110 . Electrical coupling of the matrix drivers  320  to the micro-LEDs  110  is disclosed further in detail below in connection with  FIGS. 19 and/or 20 . 
     At block  1818 , the example method  1800  includes removing the carrier substrate  1002  from the package resin layer  418 . For example, the carrier substrate  1002  may be lifted off and/or otherwise removed during installation of the micro-LED assembly  400 , the second micro-LED assembly  1600 , and/or the third micro-LED assembly  1700  in the micro-LED display  300  of  FIGS. 3A and/or 3B . 
     At block  1820 , the example method  1800  includes coupling the cover glass  1502  to the package resin layer  418 . For example, the cover glass  1502  is coupled to the package resin layer  418  via the adhesive layer  1504 . In some examples, instead of coupling the cover glass  1502  to the package resin layer  418 , the carrier substrate  1002  is not removed at block  1818  and the carrier substrate  1002  serves to protect and/or provide support to the micro-LED assembly  400 , the second micro-LED assembly  1600 , and/or the third micro-LED assembly  1700  instead of the cover glass  1502 . 
       FIG. 19  is a flowchart representative of a first example method  1900  of electrically coupling at least one of the matrix drivers  320  to the example micro-LEDs  110  in connection with block  1816  of  FIG. 16 . In some examples, the first method  1900  of  FIG. 19  is performed to manufacture the example micro-LED assembly  400  of  FIG. 3 . 
     The first example method  1900  begins at block  1902  by coupling the bonding material  428  to the second surface  426  on the second side  310  of the substrate  404 . For example, the bonding material  428  is coupled to the second surface  426  and electrically coupled to the second contact pads  424  thereupon. In some examples, the bonding material  428  provides a substantially smooth and/or flat surface to enable coupling of drivers (e.g., the matrix drivers  320  and/or the assist driver circuits  330 ) thereto. For example, the bonding material  428  can account for irregularities and/or non-flat surface features of the second surface  426  created during etching, polishing, and/or lasering of the substrate  404 . 
     At block  1904 , the first example method  1900  includes electrically coupling at least one of the matrix drivers  320  to the second contact pads  424  via the bonding material  428 . In such examples, the matrix driver(s)  320  is/are electrically coupled, via the bonding material  428  and the conductive paths  402 , to corresponding ones of the micro-LEDs  110  to control operation thereof. For example, the matrix driver(s)  320  can provide electrical signals to the micro-LEDs  110  to turn the micro-LEDs  110  on or off and/or vary a brightness thereof. In some examples, the micro-LED assembly  400  does not include the bonding material  428 , and the matrix driver(s)  320  is/are instead directly coupled to the second contact pads  424 . 
       FIG. 20  is a flowchart representative of a second example method  2000  of electrically coupling the matrix driver(s)  320  to the example micro-LEDs  110  in connection with block  1816  of  FIG. 16 . In some examples, the method  2000  of  FIG. 20  is performed to manufacture the second example micro-LED assembly  1600  of  FIG. 16  and/or the third example micro-LED assembly  1700  of  FIG. 17 . 
     The second example method  2000  begins at block  2002  by fabricating unitary tiles of the example micro-LEDs  110 . For example, the first micro-LED matrix tile  1601 A of  FIG. 16  is fabricated to include a first portion of the micro-LEDs  110 , and the second micro-LED matrix tiles  1601 B of  FIG. 16  is fabricated to include a second portion of the micro-LEDs  110 . 
     At block  2004 , the second example method  2000  includes mounting the unitary tiles to the first side  1604  of the PCB  1602 . For example, the unitary tiles (e.g., the micro-LED matrix tiles  1601 A,  1601 B) are electrically coupled to the third contact pads  1610  of the PCB  1602 . In such examples, the third contact pads  1610  are further electrically coupled to the second contact pads  424  of the unitary tiles  1601 A,  1601 B to electrically couple the PCB  1602  to the conductive paths  402  and, thus, to the micro-LEDs  110 . 
     At block  2006 , the second example method  2000  includes mounting one or more drivers to the second side  1606  of the PCB  1602 . For example, the matrix driver(s)  320 , the assist driver circuit  330 , and/or the timing controller  1702  is/are electrically coupled to the fourth contact pads  1612  on the second side  1606  of the PCB  1602 . In such examples, the PCB  1602  electrically couples the matrix driver(s)  320  to the micro-LEDs  110 , and/or couples the matrix driver(s)  320  to the assist driver circuit  330  and/or the timing controller  1702 . 
     “Including” and “comprising” (and all forms and tenses thereof) are used herein to be open ended terms. Thus, whenever a claim employs any form of “include” or “comprise” (e.g., comprises, includes, comprising, including, having, etc.) as a preamble or within a claim recitation of any kind, it is to be understood that additional elements, terms, etc., may be present without falling outside the scope of the corresponding claim or recitation. As used herein, when the phrase “at least” is used as the transition term in, for example, a preamble of a claim, it is open-ended in the same manner as the term “comprising” and “including” are open ended. The term “and/or” when used, for example, in a form such as A, B, and/or C refers to any combination or subset of A, B, C such as (1) A alone, (2) B alone, (3) C alone, (4) A with B, (5) A with C, (6) B with C, or (7) A with B and with C. As used herein in the context of describing structures, components, items, objects and/or things, the phrase “at least one of A and B” is intended to refer to implementations including any of (1) at least one A, (2) at least one B, or (3) at least one A and at least one B. Similarly, as used herein in the context of describing structures, components, items, objects and/or things, the phrase “at least one of A or B” is intended to refer to implementations including any of (1) at least one A, (2) at least one B, or (3) at least one A and at least one B. As used herein in the context of describing the performance or execution of processes, instructions, actions, activities and/or steps, the phrase “at least one of A and B” is intended to refer to implementations including any of (1) at least one A, (2) at least one B, or (3) at least one A and at least one B. Similarly, as used herein in the context of describing the performance or execution of processes, instructions, actions, activities and/or steps, the phrase “at least one of A or B” is intended to refer to implementations including any of (1) at least one A, (2) at least one B, or (3) at least one A and at least one B. 
     As used herein, singular references (e.g., “a”, “an”, “first”, “second”, etc.) do not exclude a plurality. The term “a” or “an” object, as used herein, refers to one or more of that object. The terms “a” (or “an”), “one or more”, and “at least one” are used interchangeably herein. Furthermore, although individually listed, a plurality of means, elements or method actions may be implemented by, e.g., the same entity or object. Additionally, although individual features may be included in different examples or claims, these may possibly be combined, and the inclusion in different examples or claims does not imply that a combination of features is not feasible and/or advantageous. 
     From the foregoing, it will be appreciated that example systems, methods, apparatus, and articles of manufacture for a micro-LED display are disclosed. Disclosed systems, methods, apparatus, and articles of manufacture provide a micro-LED matrix of micro-LEDs on a first side (e.g., a top surface) of a substrate, and one or more drivers to control the micro-LEDs on a second side (e.g., a bottom surface) of the substrate opposite the first side. The example substrate includes example conductive paths that enable transmission of control signals from the driver(s) to the micro-LEDs, such that the driver(s) can control multiple pixel elements of the micro-LED display. Advantageously, by removing the driver(s) from the top surface of the substrate, disclosed systems, methods, apparatus, and articles of manufacture enable a reduction in pixel pitch of the micro-LED display and, thus, improve a resolution of the micro-LED display. Furthermore, disclosed systems, methods, apparatus, and articles of manufacture reduce manufacturing and/or parts costs by reducing a number of the driver(s) to be implemented on the micro-LED display. The disclosed systems, methods, apparatus, and articles of manufacture are accordingly directed to one or more improvement(s) in the operation of a machine such as a computer or other electronic and/or mechanical device. 
     Example apparatus, methods, and articles of manufacture for a micro-LED display are disclosed herein. Further examples and combinations thereof include the following: 
     Example 1 includes an apparatus for a micro-LED display, the apparatus comprising a substrate, a micro-LED matrix on a first side of the substrate, a driver circuit on a second side of the substrate, the second side opposite the first side, and a conductive path in the substrate to extend between the first side and the second side to electrically couple the micro-LED matrix to the driver circuit. 
     Example 2 includes the apparatus of example 1, wherein the substrate is a polyimide substrate. 
     Example 3 includes the apparatus of example 1, wherein the conductive path is a first conductive path and the driver circuit is a matrix driver circuit, further including at least one of an assist driver circuit or a timing controller on the second side of the substrate, and a second conductive path in the substrate to electrically couple the at least one of the assist driver circuit or the timing controller to the matrix driver circuit. 
     Example 4 includes the apparatus of example 1, wherein the driver circuit is to control a plurality of pixels of the micro-LED display. 
     Example 5 includes the apparatus of example 1, further including a package resin layer to envelop the micro-LED matrix. 
     Example 6 includes the apparatus of example 1, wherein the driver circuit is a first matrix driver circuit to control operation of first LEDs in the micro-LED matrix, further including a second matrix driver circuit on the second side of the substrate, the second matrix driver circuit to control operation of second LEDs in the micro-LED matrix. 
     Example 7 includes the apparatus of example 1, wherein the substrate is a first substrate, further including a second substrate coupled to the second side of the first substrate, the second side of the first substrate facing a third side of the second substrate, the driver circuit coupled to a fourth side of the second substrate opposite the third side, the second substrate to electrically couple the driver circuit to micro-LEDs of the micro-LED matrix. 
     Example 8 includes the apparatus of example 7, wherein the first substrate is a polyimide substrate and the second substrate is a printed circuit board. 
     Example 9 includes the apparatus of example 7, wherein the micro-LED matrix is a first micro-LED matrix, further including a second micro-LED matrix coupled to a third substrate on the third side of the second substrate. 
     Example 10 includes the apparatus of example 9, wherein the driver circuit is a first matrix driver circuit and the micro-LEDs are first micro-LEDs, further including a second matrix driver circuit on the fourth side of the second substrate, the second substrate to electrically couple the second matrix driver circuit to second micro-LEDs of the second micro-LED matrix. 
     Example 11 includes an apparatus, comprising an array of micro-LEDs, an IC chip to drive the micro-LEDs in the array of micro-LEDs, and a substrate disposed between the array of micro-LEDs and the IC chip, the substrate to electrically couple the array of micro-LEDs and the IC chip. 
     Example 12 includes the apparatus of example 11, further including a conductive path in the substrate, the conductive path coupled between a first contact pad on a first side of the substrate and a second contact pad on a second side of the substrate. 
     Example 13 includes the apparatus of example 12, wherein the first contact pad protrudes from a first surface of the substrate and the second contact pad is substantially level with a second surface of the substrate. 
     Example 14 includes the apparatus of example 11, wherein the IC chip is a first IC chip and the array of micro-LEDs is a first array of micro-LEDs, further including a second IC chip to drive micro-LEDs in a second array of micro-LEDs, the substrate disposed between the second array of micro-LEDs and the second IC chip. 
     Example 15 includes the apparatus of example 14, wherein the substrate is a first substrate, further including a second substrate disposed between the first array of micro-LEDs and the first substrate, and a third substrate disposed between the second array of micro-LEDs and the first substrate. 
     Example 16 includes the apparatus of example 15, wherein the first substrate is a printed circuit board and the second and third substrates include a polyimide material. 
     Example 17 includes a method to manufacture a micro-LED display, the method comprising providing a substrate that includes a conductive path, the conductive path electrically coupled between a first contact pad on a first side of the substrate and a second contact pad on a second side of the substrate, the first side opposite the second side, electrically coupling micro-LEDs of a micro-LED matrix to the first contact pads, and electrically coupling a driver circuit to the second contact pad, the conductive path to electrically couple the micro-LEDs to the driver circuit. 
     Example 18 includes the method of example 17, wherein the providing of the substrate includes depositing layers of polyimide material and conductive material on a sacrificial layer of the polyimide material, the conductive material defining the conductive path, and removing the sacrificial layer to expose the second contact pad on the second side of the substrate. 
     Example 19 includes the method of example 18, wherein the removing of the sacrificial layer includes at least one of etching, polishing, or laser removal. 
     Example 20 includes the method of example 18, wherein the providing of the substrate includes depositing the sacrificial layer on a glass substrate, and removing the glass substrate from the sacrificial layer prior to the removing of the sacrificial layer. 
     Example 21 includes the method of example 17, further including coupling a printed circuit board between the substrate and the driver circuit. 
     Example 22 includes the method of example 17, further including depositing a package resin layer on the first side of the substrate, the package resin layer to envelop the micro-LEDs. 
     Example 23 includes the method of example 17, wherein the driver circuit is a matrix driver circuit, further including coupling an assist driver circuit to the second side of the substrate. 
     The following claims are hereby incorporated into this Detailed Description by this reference. Although certain example systems, methods, apparatus, and articles of manufacture have been disclosed herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all systems, methods, apparatus, and articles of manufacture fairly falling within the scope of the claims of this patent.