PATENT DOCUMENT

Publication Number: US-11119616-B2
Application Number: US-201916661847-A
Country: US
Kind Code: B2

Title: Trace transfer techniques for touch sensor panels with flex circuits

Abstract:
Trace transfer techniques can be used to couple touch electrodes to touch sensing circuitry with a reduced border region around a touch sensor panel. Touch electrodes on a first side of the substrate can be routed to a bond pad region on the second side of the substrate via a trace transfer technique to enable single-sided bonding of a double-sided touch sensor panel. Trace transfer techniques can also be used to couple conductive traces on a first side of the substrate to a flex circuit oriented perpendicular to or otherwise not parallel to the first side of the substrate. Orienting the flex circuit in this way can allow the flex circuit to connect to touch circuitry with reduced bending as compared with the amount of bending of the flex circuit when oriented substantially parallel to the substrate.

Claims:
The invention claimed is: 
     
       1. A touch sensor panel, comprising:
 a substrate; 
 touch electrodes disposed on a first surface of the substrate; and 
 a flex circuit coupled to the substrate via bonding to a second surface of the substrate that is positioned at a non-parallel angle with respect to the first surface of the substrate, wherein a first side of the flex circuit is bonded to the second surface with an adhesive, wherein the flex circuit includes conductive traces coupled to the touch electrodes, and wherein the conductive traces of the flex circuit are disposed on a second side of the flex circuit opposite the first side of the flex circuit. 
 
     
     
       2. The touch sensor panel of  claim 1 , further comprising:
 bond pads formed on the first surface of the substrate and coupled to the touch electrodes; 
 wherein the conductive traces of the flex circuit are coupled to the touch electrodes via the bond pads. 
 
     
     
       3. The touch sensor panel of  claim 2 , further comprising:
 conductive traces configured to couple the bond pads to the conductive traces of the flex circuit. 
 
     
     
       4. The touch sensor panel of  claim 3 , wherein the conductive traces configured to couple the bond pads to the conductive traces of the flex circuit are formed from a metallic paste. 
     
     
       5. The touch sensor panel of  claim 4 , wherein the metallic paste is a silver paste. 
     
     
       6. The touch sensor panel of  claim 4 , wherein the metallic paste is a copper paste. 
     
     
       7. The touch sensor panel of  claim 3 , wherein the conductive traces configured to couple the bond pads to the conductive traces of the flex circuit wrap around from the first surface of the substrate to the flex circuit oriented perpendicular to the first surface of the substrate. 
     
     
       8. The touch sensor panel of  claim 3 , further comprising:
 potting including a first section disposed parallel to a plane of the first surface of the substrate and a second section disposed perpendicular to the first surface of the substrate, wherein, at least part of the conductive traces configured to couple the bond pads to the conductive traces of the flex circuit are disposed between the flex circuit and the potting. 
 
     
     
       9. The touch sensor panel of  claim 3 , wherein a first thickness of at least one conductive trace of the conductive traces configured to couple the bond pads to the conductive traces of the flex circuit at a first distance from a first edge of the substrate is greater than a second thickness of the at least one of the conductive trace at a second distance from the first edge, the second distance greater than the first distance. 
     
     
       10. The touch sensor panel of  claim 9 , wherein a first width of the at least one conductive trace at the first distance from the first edge is greater than a second width of the at least one of the conductive trace at the second distance from the first edge. 
     
     
       11. The touch sensor panel of  claim 9 , wherein a thickness of the at least one conductive trace overlapping at least one bond pad of the bond pads is less than 20 microns. 
     
     
       12. The touch sensor panel of  claim 1 , further comprising:
 an optical polarizer, the optical polarizer coupled to a third surface of the substrate opposite the first surface of the substrate, wherein 
 the flex circuit is bonded to the second surface of the substrate and bonded to the optical polarizer with the adhesive. 
 
     
     
       13. The touch sensor panel of  claim 12 , wherein the flex circuit is bonded to the polarizer with a second adhesive different than the adhesive bonding the flex circuit to the substrate and to the optical polarizer. 
     
     
       14. The touch sensor panel of  claim 12 , further comprising a strain relief coupled to the flex circuit and coupled to the optical polarizer. 
     
     
       15. The touch sensor panel of  claim 1 , wherein the touch electrodes are formed from indium tin oxide (ITO). 
     
     
       16. The touch sensor panel of  claim 1 , wherein the second surface of the substrate is perpendicular to the first surface of the substrate. 
     
     
       17. The touch sensor panel of  claim 1 , further comprising a strain relief coupled to the flex circuit and coupled to the substrate. 
     
     
       18. The touch sensor panel of  claim 1 , wherein the adhesive is non-conductive such that the bond between the second surface of the substrate and the flex circuit is non-conductive. 
     
     
       19. The touch sensor panel of  claim 1 , further comprising:
 conductive traces configured to couple the touch electrodes to the conductive traces of the flex circuit, wrapping around from the first surface of the substrate to the conductive traces of the flex circuit on the second side of the flex circuit. 
 
     
     
       20. A touch sensor panel, comprising:
 a substrate; 
 touch electrodes disposed on a first surface of the substrate; 
 bond pads formed on the first surface of the substrate and coupled to the touch electrodes; 
 a flex circuit coupled to the substrate via bonding to a surface that is positioned at a non-parallel angle with respect to the first surface of the substrate, the flex circuit including conductive traces coupled to the touch electrodes; and 
 conductive traces configured to couple the bond pads to the conductive traces of the flex circuit; 
 wherein the conductive traces of the flex circuit are coupled to the touch electrodes via the bond pads and the conductive traces configured to couple the bond pads to the conductive traces of the flex circuit; and 
 wherein a first thickness of at least one conductive trace of the conductive traces configured to couple the bond pads to the conductive traces of the flex circuit at a first distance from a first edge of the substrate is greater than a second thickness of the at least one of the conductive trace at a second distance from the first edge, the second distance greater than the first distance. 
 
     
     
       21. A touch sensor panel, comprising:
 a substrate; 
 touch electrodes disposed on a first surface of the substrate; 
 bond pads formed on the first surface of the substrate and coupled to the touch electrodes; 
 a flex circuit coupled to the substrate via bonding to a surface that is positioned at a non-parallel angle with respect to the first surface of the substrate, the flex circuit including conductive traces coupled to the touch electrodes; and 
 conductive traces configured to couple the bond pads to the conductive traces of the flex circuit; 
 wherein the conductive traces of the flex circuit are coupled to the touch electrodes via the bond pads and the conductive traces configured to couple the bond pads to the conductive traces of the flex circuit; and 
 wherein a first width of at least one conductive trace of the conductive traces configured to couple the bond pads to the conductive traces of the flex circuit at a first distance from a first edge of the substrate is greater than a second width of the at least one of the conductive trace at a second distance from the first edge, the second distance greater than the first distance.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. 119(e) of U.S. Provisional Patent Application No. 62/754,558, filed Nov. 1, 2018, U.S. Provisional Patent Application No. 62/812,172, filed Feb. 28, 2019, U.S. Provisional Patent Application No. 62/872,054, filed Jul. 9, 2019, the contents of which are incorporated herein by reference in their entirety for all purposes. 
    
    
     FIELD OF THE DISCLOSURE 
     This relates generally to touch sensitive devices and, more specifically, to touch sensitive devices including flex circuits that use trace transfer techniques. 
     BACKGROUND OF THE DISCLOSURE 
     Many types of input devices are presently available for performing operations in a computing system, such as buttons or keys, mice, trackballs, joysticks, touch sensor panels, touch screens and the like. Touch screens, in particular, are popular because of their ease and versatility of operation as well as their declining price. Touch screens can include a touch sensor panel, which can be a clear panel with a touch-sensitive surface, and a display device such as a liquid crystal display (LCD), light emitting diode (LED) display or organic light emitting diode (OLED) display that can be positioned partially or fully behind the panel so that the touch-sensitive surface can cover at least a portion of the viewable area of the display device. Touch screens can allow a user to perform various functions by touching the touch sensor panel using a finger, stylus or other object at a location often dictated by a user interface (UI) being displayed by the display device. In general, touch screens can recognize a touch and the position of the touch on the touch sensor panel, and the computing system can then interpret the touch in accordance with the display appearing at the time of the touch, and thereafter can perform one or more actions based on the touch. In the case of some touch sensing systems, a physical touch on the display is not needed to detect a touch. For example, in some capacitive-type touch sensing systems, fringing electrical fields used to detect touch can extend beyond the surface of the display, and objects approaching near the surface may be detected near the surface without actually touching the surface. 
     Capacitive touch sensor panels can be formed by a matrix of partially or fully transparent or non-transparent conductive plates (e.g., touch electrodes) made of materials such as Indium Tin Oxide (ITO). In some examples, the conductive plates can be formed from other materials including conductive polymers, metal mesh, graphene, nanowires (e.g., silver nanowires) or nanotubes (e.g., carbon nanotubes). It is due in part to their substantial transparency that some capacitive touch sensor panels can be overlaid on a display to form a touch screen, as described above. Some touch screens can be formed by at least partially integrating touch sensing circuitry into a display pixel stack-up (i.e., the stacked material layers forming the display pixels). 
     BRIEF SUMMARY OF THE DISCLOSURE 
     This relates generally to touch sensitive devices and, more specifically, to touch sensitive devices including flex circuits that use trace transfer techniques. One or more touch electrodes on a first side of the substrate can be routed to a bond pad region on the second side of the substrate via a trace transfer technique. For example, one or more conductive traces can wrap around one or more edges of the substrate from the first side to the second side. One or more touch electrodes on the second side of the substrate can also be routed to the bond pad region on the second side of the substrate. The touch sensor panel can further include a flex circuit that couples to the bond pad region to connect the touch electrodes on the first side of the substrate and the touch electrodes on the second side of the substrate to touch circuitry (e.g., on a separate printed circuit board (PCB)). 
     In some examples, trace transfer techniques can be used to connect conductive traces (e.g., conductive traces coupled to one or more touch sensor electrodes of a touch sensor panel) to a flex circuit oriented perpendicular to or otherwise not parallel to the touch surface of the touch sensor panel. Orienting the flex circuit in this way can enable the flex circuit to connect to touch circuitry with reduced bending as compared with the amount of bending of the flex circuit when oriented substantially parallel to the substrate (e.g., bending 90 degrees as opposed to 180 degrees). 
     In some examples, one or more of the bond pads described herein can include a conductive material (e.g., copper) separated from an edge of the substrate by threshold distance. In some examples, one or more of the bond pads described herein can including a conductive material (e.g., copper) including a tail portion that extends to the edge of the substrate. The width of the tail portion can be narrower than remaining portion of the bond pad. In some examples, the thickness and/or width of the conductive traces can be increased near edges of the substrate to provide increased structural stability. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1E  illustrate example systems that can use trace transfer techniques according to examples of the disclosure. 
         FIG. 2  illustrates an example computing system including a touch screen that can use trace transfer techniques according to examples of the disclosure. 
         FIG. 3A  illustrates an exemplary touch sensor circuit corresponding to a self-capacitance measurement of a touch node electrode and sensing circuit according to examples of the disclosure. 
         FIG. 3B  illustrates an exemplary touch sensor circuit corresponding to a mutual-capacitance drive line and sense line and sensing circuit according to examples of the disclosure. 
         FIG. 4A  illustrates touch screen with touch electrodes arranged in rows and columns according to examples of the disclosure. 
         FIG. 4B  illustrates touch screen with touch node electrodes arranged in a pixelated touch node electrode configuration according to examples of the disclosure. 
         FIG. 5  illustrates a cross-section of a touch sensor panel implemented as a double-sided touch sensor panel according to examples of the disclosure. 
         FIGS. 6A-6D  illustrate an exemplary touch sensor panel including bond pads and flex circuit connections on both sides of a substrate according to some examples of the disclosure. 
         FIGS. 7A-7H  illustrate an exemplary touch sensor panel including a flex circuit connection on one side of a substrate according to some examples of the disclosure. 
         FIG. 8A  illustrates an exemplary touch sensor panel including perpendicular bonding of the flex circuit according to some examples of the disclosure. 
         FIG. 8B  illustrates an exemplary touch sensor panel including perpendicular bonding of the flex circuit according to some examples of the disclosure. 
         FIG. 8C  illustrates an exemplary touch sensor panel including perpendicular bonding of the flex circuit according to some examples of the disclosure. 
         FIGS. 9A-10C  illustrate exemplary bond pads formed on a substrate according to examples of the disclosure. 
         FIGS. 11A-11D  illustrate exemplary touch sensor panels including conductive traces with variable thickness according to examples of the disclosure 
         FIG. 12  illustrates exemplary conductive traces with variable width according to examples of the disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     In the following description of examples, reference is made to the accompanying drawings which form a part hereof, and in which it is shown by way of illustration specific examples that can be practiced. It is to be understood that other examples can be used and structural changes can be made without departing from the scope of the disclosed examples. 
     This relates to touch sensor panels with a single-side bonding to couple touch electrodes on each side of a substrate of the touch sensor panel to touch sensing circuitry. In some examples, a double-sided touch sensor panel can include touch electrodes on two sides of the substrate. One or more touch electrodes on a first side of the substrate can be routed to a bond pad region on the second side of the substrate via a trace transfer technique. For example, one or more conductive traces can wrap around one or more edges of the substrate from the first side to the second side. One or more touch electrodes on the second side of the substrate can also be routed to the bond pad region on the second side of the substrate. The touch sensor panel can further include a flex circuit that couples to the bond pad region to connect the touch electrodes on the first side of the substrate and the touch electrodes on the second side of the substrate to touch circuitry (e.g., on a separate printed circuit board (PCB)). In some examples, the trace transfer techniques can be used for a single-sided touch sensor panel to route touch electrodes on a first side of the substrate to a bond pad on the second side of the substrate. 
     In some examples, trace transfer techniques can be used to connect conductive traces (e.g., conductive traces coupled to one or more touch sensor electrodes of a touch sensor panel) to a flex circuit oriented perpendicular to or otherwise not parallel to the touch surface of the touch sensor panel. Orienting the flex circuit in this way can enable the flex circuit to connect to touch circuitry with reduced bending as compared with the amount of bending of the flex circuit when oriented substantially parallel to the substrate (e.g., bending 90 degrees as opposed to 180 degrees). 
     In some examples, one or more of the bond pads described herein can include a conductive material (e.g., copper) separated from an edge of the substrate by threshold distance. In some examples, one or more of the bond pads described herein can including a conductive material (e.g., copper) including a tail portion that extends to the edge of the substrate. The width of the tail portion can be narrower than remaining portion of the bond pad. In some examples, the thickness and/or width of the conductive traces can be increased near edges of the substrate to provide increased structural stability. 
       FIGS. 1A-1E  illustrate example systems that can use trace transfer techniques according to examples of the disclosure.  FIG. 1A  illustrates an example mobile telephone  136  that includes a touch screen  124  that can use trace transfer techniques according to examples of the disclosure.  FIG. 1B  illustrates an example digital media player  140  that includes a touch screen  126  that can use trace transfer techniques according to examples of the disclosure.  FIG. 1C  illustrates an example personal computer  144  that includes a touch screen  128  that can use trace transfer techniques according to examples of the disclosure.  FIG. 1D  illustrates an example tablet computing device  148  that includes a touch screen  130  that can use trace transfer techniques according to examples of the disclosure.  FIG. 1E  illustrates an example wearable device  150  that includes a touch screen  132  and can be attached to a user using a strap  152  and that can use trace transfer techniques according to examples of the disclosure. It is understood that a touch screen and trace transfer techniques can be implemented in other devices as well. Additionally it should be understood that although the disclosure herein primarily focuses on touch screens, the disclosure of trace transfer techniques can be implemented for devices including touch sensor panels (and displays) that may not be implemented as a touch screen. 
     In some examples, touch screens  124 ,  126 ,  128 ,  130  and  132  can be can be based on self-capacitance. A self-capacitance based touch system can include a matrix of small, individual plates of conductive material or groups of individual plates of conductive material forming larger conductive regions that can be referred to as touch electrodes or as touch node electrodes (as described below with reference to  FIG. 4B ). For example, a touch screen can include a plurality of individual touch electrodes, each touch electrode identifying or representing a unique location (e.g., a touch node) on the touch screen at which touch or proximity is to be sensed, and each touch node electrode being electrically isolated from the other touch node electrodes in the touch screen/panel. Such a touch screen can be referred to as a pixelated self-capacitance touch screen, though it is understood that in some examples, the touch node electrodes on the touch screen can be used to perform scans other than self-capacitance scans on the touch screen (e.g., mutual capacitance scans). During operation, a touch node electrode can be stimulated with an alternating current (AC) waveform, and the self-capacitance to ground of the touch node electrode can be measured. As an object approaches the touch node electrode, the self-capacitance to ground of the touch node electrode can change (e.g., increase). This change in the self-capacitance of the touch node electrode can be detected and measured by the touch sensing system to determine the positions of multiple objects when they touch, or come in proximity to, the touch screen. In some examples, the touch node electrodes of a self-capacitance based touch system can be formed from rows and columns of conductive material, and changes in the self-capacitance to ground of the rows and columns can be detected, similar to above. In some examples, a touch screen can be multi-touch, single touch, projection scan, full-imaging multi-touch, capacitive touch, etc. 
     In some examples, touch screens  124 ,  126 ,  128 ,  130  and  132  can be based on mutual capacitance. A mutual capacitance based touch system can include electrodes arranged as drive and sense lines that may cross over each other on different layers (in a double-sided configuration), or may be adjacent to each other on the same layer (e.g., as described below with reference to FIG.  4 A). The crossing or adjacent locations can form touch nodes. During operation, the drive line can be stimulated with an AC waveform and the mutual capacitance of the touch node can be measured. As an object approaches the touch node, the mutual capacitance of the touch node can change (e.g., increase). This change in the mutual capacitance of the touch node can be detected and measured by the touch sensing system to determine the positions of multiple objects when they touch, or come in proximity to, the touch screen. As described herein, in some examples, a mutual capacitance based touch system can form touch nodes from a matrix of small, individual plates of conductive material. 
     In some examples, touch screens  124 ,  126 ,  128 ,  130  and  132  can be based on mutual capacitance and/or self-capacitance. The electrodes can be arrange as a matrix of small, individual plates of conductive material (e.g., as in touch node electrodes  408  in touch screen  402  in  FIG. 4B ) or as drive lines and sense lines (e.g., as in row touch electrodes  404  and column touch electrodes  406  in touch screen  400  in  FIG. 4A ), or in another pattern. The electrodes can be configurable for mutual capacitance or self-capacitance sensing or a combination of mutual and self-capacitance sensing. For example, in one mode of operation electrodes can be configured to sense mutual capacitance between electrodes and in a different mode of operation electrodes can be configured to sense self-capacitance of electrodes. In some examples, some of the electrodes can be configured to sense mutual capacitance therebetween and some of the electrodes can be configured to sense self-capacitance thereof. 
       FIG. 2  illustrates an example computing system including a touch screen that can use trace transfer techniques according to examples of the disclosure. Computing system  200  can be included in, for example, a mobile phone, tablet, touchpad, portable or desktop computer, portable media player, wearable device or any mobile or non-mobile computing device that includes a touch screen or touch sensor panel. Computing system  200  can include a touch sensing system including one or more touch processors  202 , peripherals  204 , a touch controller  206 , and touch sensing circuitry (described in more detail below). Peripherals  204  can include, but are not limited to, random access memory (RAM) or other types of memory or storage, watchdog timers and the like. Touch controller  206  can include, but is not limited to, one or more sense channels  208 , channel scan logic  210  and driver logic  214 . Channel scan logic  210  can access RAM  212 , autonomously read data from the sense channels and provide control for the sense channels. In addition, channel scan logic  210  can control driver logic  214  to generate stimulation signals  216  at various frequencies and/or phases that can be selectively applied to drive regions of the touch sensing circuitry of touch screen  220 , as described in more detail below. In some examples, touch controller  206 , touch processor  202  and peripherals  204  can be integrated into a single application specific integrated circuit (ASIC), and in some examples can be integrated with touch screen  220  itself. 
     It should be apparent that the architecture shown in  FIG. 2  is only one example architecture of computing system  200 , and that the system could have more or fewer components than shown, or a different configuration of components. The various components shown in  FIG. 2  can be implemented in hardware, software, firmware or any combination thereof, including one or more signal processing and/or application specific integrated circuits. 
     Computing system  200  can include a host processor  228  for receiving outputs from touch processor  202  and performing actions based on the outputs. For example, host processor  228  can be connected to program storage  232  and a display controller/driver  234  (e.g., a Liquid-Crystal Display (LCD) driver). It is understood that although some examples of the disclosure may described with reference to LCD displays, the scope of the disclosure is not so limited and can extend to other types of displays, such as Light-Emitting Diode (LED) displays, including Organic LED (OLED), Active-Matrix Organic LED (AMOLED) and Passive-Matrix Organic LED (PMOLED) displays. Display driver  234  can provide voltages on select (e.g., gate) lines to each pixel transistor and can provide data signals along data lines to these same transistors to control the pixel display image. 
     Host processor  228  can use display driver  234  to generate a display image on touch screen  220 , such as a display image of a user interface (UI), and can use touch processor  202  and touch controller  206  to detect a touch on or near touch screen  220 , such as a touch input to the displayed UI. The touch input can be used by computer programs stored in program storage  232  to perform actions that can include, but are not limited to, moving an object such as a cursor or pointer, scrolling or panning, adjusting control settings, opening a file or document, viewing a menu, making a selection, executing instructions, operating a peripheral device connected to the host device, answering a telephone call, placing a telephone call, terminating a telephone call, changing the volume or audio settings, storing information related to telephone communications such as addresses, frequently dialed numbers, received calls, missed calls, logging onto a computer or a computer network, permitting authorized individuals access to restricted areas of the computer or computer network, loading a user profile associated with a user&#39;s preferred arrangement of the computer desktop, permitting access to web content, launching a particular program, encrypting or decoding a message, and/or the like. Host processor  228  can also perform additional functions that may not be related to touch processing. 
     Note that one or more of the functions described herein, including the configuration of switches, can be performed by firmware stored in memory (e.g., one of the peripherals  204  in  FIG. 2 ) and executed by touch processor  202 , or stored in program storage  232  and executed by host processor  228 . The firmware can also be stored and/or transported within any non-transitory computer-readable storage medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “non-transitory computer-readable storage medium” can be any medium (excluding signals) that can contain or store the program for use by or in connection with the instruction execution system, apparatus, or device. In some examples, RAM  212  or program storage  232  (or both) can be a non-transitory computer readable storage medium. One or both of RAM  212  and program storage  232  can have stored therein instructions, which when executed by touch processor  202  or host processor  228  or both, can cause the device including computing system  200  to perform one or more functions and methods of one or more examples of this disclosure. The computer-readable storage medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, a portable computer diskette (magnetic), a random access memory (RAM) (magnetic), a read-only memory (ROM) (magnetic), an erasable programmable read-only memory (EPROM) (magnetic), a portable optical disc such a CD, CD-R, CD-RW, DVD, DVD-R, or DVD-RW, or flash memory such as compact flash cards, secured digital cards, USB memory devices, memory sticks, and the like. 
     The firmware can also be propagated within any transport medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “transport medium” can be any medium that can communicate, propagate or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The transport medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic or infrared wired or wireless propagation medium. 
     Touch screen  220  can be used to derive touch information at multiple discrete locations of the touch screen, referred to herein as touch nodes. Touch screen  220  can include touch sensing circuitry that can include a capacitive sensing medium having a plurality of drive lines  222  and a plurality of sense lines  223 . It should be noted that the term “lines” is sometimes used herein to mean simply conductive pathways, as one skilled in the art will readily understand, and is not limited to elements that are strictly linear, but includes pathways that change direction, and includes pathways of different size, shape, materials, etc. Drive lines  222  can be driven by stimulation signals  216  from driver logic  214  through a drive interface  224 , and resulting sense signals  217  generated in sense lines  223  can be transmitted through a sense interface  225  to sense channels  208  in touch controller  206 . In this way, drive lines and sense lines can be part of the touch sensing circuitry that can interact to form capacitive sensing nodes, which can be thought of as touch picture elements (touch pixels) and referred to herein as touch nodes, such as touch nodes  226  and  227 . This way of understanding can be particularly useful when touch screen  220  is viewed as capturing an “image” of touch (“touch image”). In other words, after touch controller  206  has determined whether a touch has been detected at each touch nodes in the touch screen, the pattern of touch nodes in the touch screen at which a touch occurred can be thought of as an “image” of touch (e.g., a pattern of fingers touching the touch screen). As used herein, an electrical component “coupled to” or “connected to” another electrical component encompasses a direct or indirect connection providing electrical path for communication or operation between the coupled components. Thus, for example, drive lines  222  may be directly connected to driver logic  214  or indirectly connected to drive logic  214  via drive interface  224  and sense lines  223  may be directly connected to sense channels  208  or indirectly connected to sense channels  208  via sense interface  225 . In either case an electrical path for driving and/or sensing the touch nodes can be provided. 
       FIG. 3A  illustrates an exemplary touch sensor circuit  300  corresponding to a self-capacitance measurement of a touch node electrode  302  and sensing circuit  314  according to examples of the disclosure. Touch node electrode  302  can correspond to a touch electrode  404  or  406  of touch screen  400  or a touch node electrode  408  of touch screen  402 . Touch node electrode  302  can have an inherent self-capacitance to ground associated with it, and also an additional self-capacitance to ground that is formed when an object, such as finger  305 , is in proximity to or touching the electrode. The total self-capacitance to ground of touch node electrode  302  can be illustrated as capacitance  304 . Touch node electrode  302  can be coupled to sensing circuit  314 . Sensing circuit  314  can include an operational amplifier  308 , feedback resistor  312  and feedback capacitor  310 , although other configurations can be employed. For example, feedback resistor  312  can be replaced by a switched capacitor resistor in order to minimize a parasitic capacitance effect that can be caused by a variable feedback resistor. Touch node electrode  302  can be coupled to the inverting input (−) of operational amplifier  308 . An AC voltage source  306  (Vac) can be coupled to the non-inverting input (+) of operational amplifier  308 . Touch sensor circuit  300  can be configured to sense changes (e.g., increases) in the total self-capacitance  304  of the touch node electrode  302  induced by a finger or object either touching or in proximity to the touch sensor panel. Output  320  can be used by a processor to determine the presence of a proximity or touch event, or the output can be inputted into a discrete logic network to determine the presence of a proximity or touch event. 
       FIG. 3B  illustrates an exemplary touch sensor circuit  350  corresponding to a mutual-capacitance drive line  322  and sense line  326  and sensing circuit  314  according to examples of the disclosure. Drive line  322  can be stimulated by stimulation signal  306  (e.g., an AC voltage signal). Stimulation signal  306  can be capacitively coupled to sense line  326  through mutual capacitance  324  between drive line  322  and the sense line. When a finger or object  305  approaches the touch node created by the intersection of drive line  322  and sense line  326 , mutual capacitance  324  can change (e.g., decrease). This change in mutual capacitance  324  can be detected to indicate a touch or proximity event at the touch node, as described herein. The sense signal coupled onto sense line  326  can be received by sensing circuit  314 . Sensing circuit  314  can include operational amplifier  308  and at least one of a feedback resistor  312  and a feedback capacitor  310 .  FIG. 3B  illustrates a general case in which both resistive and capacitive feedback elements are utilized. The sense signal (referred to as V in ) can be inputted into the inverting input of operational amplifier  308 , and the non-inverting input of the operational amplifier can be coupled to a reference voltage V ref . Operational amplifier  308  can drive its output to voltage V o  to keep V in  substantially equal to V ref , and can therefore maintain V in  constant or virtually grounded. A person of skill in the art would understand that in this context, equal can include deviations of up to 15%. Therefore, the gain of sensing circuit  314  can be mostly a function of the ratio of mutual capacitance  324  and the feedback impedance, comprised of resistor  312  and/or capacitor  310 . The output of sensing circuit  314  Vo can be filtered and heterodyned or homodyned by being fed into multiplier  328 , where Vo can be multiplied with local oscillator  330  to produce V detect . V detect  can be inputted into filter  332 . One skilled in the art will recognize that the placement of filter  332  can be varied; thus, the filter can be placed after multiplier  328 , as illustrated, or two filters can be employed: one before the multiplier and one after the multiplier. In some examples, there can be no filter at all. The direct current (DC) portion of V detect  can be used to determine if a touch or proximity event has occurred. 
     Referring back to  FIG. 2 , in some examples, touch screen  220  can be an integrated touch screen in which touch sensing circuit elements of the touch sensing system can be integrated into the display pixel stack-ups of a display. The circuit elements in touch screen  220  can include, for example, elements that can exist in LCD or other displays (LED display, OLED display, etc.), such as one or more pixel transistors (e.g., thin film transistors (TFTs)), gate lines, data lines, pixel electrodes and common electrodes. In a given display pixel, a voltage between a pixel electrode and a common electrode can control a luminance of the display pixel. The voltage on the pixel electrode can be supplied by a data line through a pixel transistor, which can be controlled by a gate line. It is noted that circuit elements are not limited to whole circuit components, such as a whole capacitor, a whole transistor, etc., but can include portions of circuitry, such as only one of the two plates of a parallel plate capacitor. 
       FIG. 4A  illustrates touch screen  400  with touch electrodes  404  and  406  arranged in rows and columns according to examples of the disclosure. Specifically, touch screen  400  can include a plurality of touch electrodes  404  disposed as rows, and a plurality of touch electrodes  406  disposed as columns. Touch electrodes  404  and touch electrodes  406  can be on the same or different material layers on touch screen  400 , and can intersect with each other, as illustrated in  FIG. 4A . In some examples, the electrodes can be formed on opposite sides of a transparent (partially or fully) substrate and from a transparent (partially or fully) semiconductor material, such as ITO, though other materials are possible. Electrodes displayed on layers on different sides of the substrate can be referred to herein as a double-sided sensor. In some examples, touch screen  400  can sense the self-capacitance of touch electrodes  404  and  406  to detect touch and/or proximity activity on touch screen  400 , and in some examples, touch screen  400  can sense the mutual capacitance between touch electrodes  404  and  406  to detect touch and/or proximity activity on touch screen  400 . 
       FIG. 4B  illustrates touch screen  402  with touch node electrodes  408  arranged in a pixelated touch node electrode configuration according to examples of the disclosure. Specifically, touch screen  402  can include a plurality of individual touch node electrodes  408 , each touch node electrode identifying or representing a unique location on the touch screen at which touch or proximity (i.e., a touch or proximity event) is to be sensed, and each touch node electrode being electrically isolated from the other touch node electrodes in the touch screen/panel, as previously described. Touch node electrodes  408  can be on the same or different material layers on touch screen  402 . In some examples, touch screen  402  can sense the self-capacitance of touch node electrodes  408  to detect touch and/or proximity activity on touch screen  402 , and in some examples, touch screen  402  can sense the mutual capacitance between touch node electrodes  408  to detect touch and/or proximity activity on touch screen  402 . 
       FIG. 5  illustrates a cross-section of a touch sensor panel  500  implemented as a double-sided touch sensor panel according to examples of the disclosure. Touch sensor panel  500  can include touch electrodes  508  on a first side of a substrate  502  (e.g., top side) arranged in a column pattern and touch electrodes  510  on a second side of a substrate  502  (opposite the first side) arranged in a row pattern. The arrangement of touch sensor panel  500  can correspond to a double-sided implementation of touch electrodes shown in  FIG. 4A , although other shapes and arrangements of electrodes are possible. Substrate  502  can include a supportive insulating material that is also, in some examples, fully or partially transparent. In some examples, the substrate can be formed from cyclic olefin polymer (COP). In some examples, the substrate  502  can include one or more substrate materials adhered together with an adhesive. In some embodiments, the electrodes can include a fully or partially transparent conductive material, such as indium-tin oxide (ITO). 
     Touch electrodes on a double-sided touch sensor panel, such as touch sensor panel  500 , can be coupled to touch sensing circuitry (e.g., touch controller  206 ), via flex circuits. Flex circuits can formed from a flexible insulating material, such as polyethylene terephthalate (PET), with conductive material (e.g., routing traces) disposed in the flexible insulating material. The flex circuits can be bonded to a substrate of the touch screen (e.g., via a bond pad region).  FIGS. 6A-6D  illustrate an exemplary touch sensor panel  600  including bond pads and flex circuit connections on both sides of a substrate according to some examples of the disclosure.  FIG. 6A  illustrates a view of a double-sided touch sensor panel  600  (e.g., corresponding to touch sensor panel  500 ) including a bond pad region and flex circuit on each of two opposite sides of a substrate according to some examples of the disclosure. The touch sensor panel  600  can include substrate  602  with touch electrodes (e.g., column electrodes  608 ) patterned on a first side (e.g., top side) and touch electrodes (e.g., row electrodes  610 ) patterned on a second side opposite the first side (e.g., bottom side). Additionally, touch sensor panel  600  can include a first bond pad region  614  on the first side of substrate  602  and a second bond pad region  616  on the second side of substrate  602 . Touch electrodes of touch sensor panel  600  can be routed to the bond pad region and coupled to touch sensing circuitry (e.g., touch controller  206 ) including sense circuitry (e.g., corresponding to sense channels  208 ) and drive circuitry (e.g., corresponding to driver logic  214 ) on PCB  612  via flex circuits. For example, a first flex circuit  606  can be coupled to a first bond pad region  614  on a first side of substrate  602  and a second flex circuit  606  can be coupled to a second bond pad region  616  on a second side of substrate  602 . In some examples, the coupling between a bond pad region  614 ,  616  and corresponding flex circuit  606  can be achieved using a conductive adhesive  604 , as described below with reference to  FIGS. 6B-6C , for example. For example, an anisotropic conductive film (ACF) can be deposited on the bond pad region and/or the flex circuit and an electrical connection can be formed by laminating the two together. Although one bond pad region and one flex circuit are illustrated on each side of substrate  602 , it should be understood that one or more bond pad regions and flex circuits could be implemented on each side of substrate  602 . 
       FIGS. 6B-6C  illustrate cross-sectional views of touch sensor panel  600  at a location including the connection between one bond pad region (e.g., corresponding to bond pad region  614  or  616 ) and one flex circuit  606 . The touch sensor panel  600  can include a substrate  602  upon which touch electrodes can be patterned on a first side and a second side (opposite the first side). For simplicity of illustration, the touch electrodes are not shown in  FIGS. 6B-6C . Touch sensor panel  600  can include a conductive adhesive  604  (e.g., an anisotropic conductive film (ACF)), and a flex circuit  606 . Flex circuit  606  can include conductive material  606   a  (e.g., routing traces) surrounded by an insulating material  606   b . The insulating material  606   b  of  FIGS. 6B-6C  is shown on top and bottom of the conductive material  606   a , but it should be understood that insulating material can also separate between the routing traces formed from conductive material  606   a . In some examples, the conductive material can be copper wire or traces and the insulating material can be PET. Flex circuit  606  can be bonded to substrate  602  at a bond pad region via the conductive adhesive, for example. The bond pad region can, in some examples, include one or more bond pads. Each of the one or more bond pads can be coupled to a touch electrode (e.g., via routing traces). In some examples, the bond pad and/or routing traces can be formed of the same material as the touch electrodes (e.g., ITO). In some examples, the bond pad and/or routing traces can be formed of a different material (e.g., copper). The conductive adhesive  604  can be disposed over the bond pads and/or over the conductive material  606   a  of the flex circuit  606  for robust mechanical and electrical connection. As shown in  FIG. 6C , in some examples, flex circuit  606  can be flexible to enable the touch electrodes (e.g., column electrodes  608  or row electrodes  610 ) on both sides of the substrate  602  to be electrically coupled to sensing circuitry in another part of the system. For example, the touch controller (including drive and sense circuitry) may be implemented on a printed circuit board (e.g., PCB  612 ) separately from the double-sided touch sensor panel. In some examples, the printed circuit board (e.g., PCB  612 ) can be disposed beneath the display/touch screen or in a border region so as not to obscure the display and/or interfere with touch sensing. The flex circuit  606  enables bending of the routing traces between the touch sensor panel substrate  602  and the printed circuit board (e.g., PCB  612 ) with the corresponding touch sensing circuitry. 
     Returning back to  FIG. 6A , although first bond pad region  614  and second bond pad region  616  are illustrated in the same region (overlapping one another) but on different sides of the substrate  602 , in some examples, the bond pad regions can be adjacent to each other and/or spaced from one another, as illustrated in  FIG. 6D .  FIG. 6D  illustrates a partial top view of the border region of a touch sensor panel  600  that includes first bond pad region  614  and second bond pad region  616 . An opaque mask  618  can differentiate between the touch and display region  620  of substrate  602  (e.g., an inner region of the electronic device that includes a touch screen) and a border region of substrate  602  (e.g., an outer region of the substrate that does not display an image and/or does not sense touch) that may not be visible outside the housing of a touch-sensitive device. The border region can include bond pad regions  614  and  616 , one on the top side and one on the bottom side, as described with reference to  FIG. 6A . Each bond pad region  614  or  616  can include one or more bond pads that couple one or more touch electrode (e.g., column electrodes  608  or row electrodes  610 ) to a corresponding one of the flex circuits (e.g., one flex circuit  606  on the top of substrate  602  and one flex circuit  606  on the bottom of substrate  602 ). 
     As described above with reference to  FIGS. 6A-6D , bond pad regions  614  and  616  can facilitate the connection of touch electrodes to a PCB  612  (including touch sensing circuitry) via flex circuits  606 . In some examples, however, it can be desirable to connect the touch electrodes of a double-sided touch sensor panel on a single side of the touch sensor panel substrate and to one bond pad region. For example, trace transfer techniques can be used to form and/or connect bond pad regions formed on one side of the substrate (e.g., a second, bottom side of a substrate) by way of a conductive connection wrapping from the first side of the substrate around edges of the substrate to the second side of the substrate (e.g., around a first edge defining a boundary of the first side of the substrate, around a third side of the substrate between the first side and the second side, and around a second edge defining a boundary of the second side). In some examples, the conductive connections can be formed by applying aerosolized conductive material (e.g., silver or other suitable conductive materials), which can be applied at relatively low temperatures, thereby protecting the other components of the touch sensor panel during manufacture. In some examples, trace transfer techniques can enable single-sided bonding of touch electrodes from both sides (top and bottom) of the double-sided touch sensor panel to be coupled to a single flex circuit, as will be described below with reference to  FIGS. 7A-H . A single-sided flex circuit connection can increase manufacturing yield, provide a more robust connection structure (damage-resistant), and shrink the border region (enabling the touch screen to occupy more of the device surface) as compared with the double-sided bonding of multiple flex circuits. 
       FIGS. 7A-7H  illustrate an exemplary touch sensor panel  700  including a flex circuit connection on one side of a substrate according to some examples of the disclosure.  FIG. 7A  illustrates a view of a double-sided touch sensor panel  700  (e.g., corresponding to touch sensor panel  500 ) including a bond pad region  715  and flex circuit  706  on one side of a substrate  702  according to some examples of the disclosure. Touch sensor panel  700  can be similar to touch sensor panel  600  described above (e.g., with reference to  FIG. 6A ), except touch sensor panel  600  includes bond pad regions  614  and  616  on each side of substrate  602  coupled to two flex circuits  606  (one per side of substrate  602 ), whereas touch sensor panel  700  includes bond pad region  715  on one side of substrate  702  coupled to one flex circuit  706 . As will be described below with reference to  FIGS. 7B-H , the bond pad region  715  on one side of substrate  702  includes connections between touch electrodes (e.g., column electrodes  708 ) disposed on a first side (e.g., the top) of the substrate  702  and PCB  712  and connections between touch electrodes (e.g., row electrodes  710 ) disposed on a second side (e.g., the bottom) of the substrate  702  and PCB  712 . 
     In some examples, the coupling between touch electrodes on the first side of the substrate  702  and the bond pad region  715 , which can be on the second side of the substrate  702  can be facilitated by trace transfer with a conductive trace, as will be described in more detail below. For example, a layer of copper, silver, or some other suitable conductive material can be deposited around edges of substrate  702  such that it wraps around the substrate  702  from the first side to the second side to connect the touch electrodes to the bond pad region  715  (e.g., via a third side, illustrated as the right side in  FIG. 7B ). The bond pad region  715  can include electrical connections to the touch sensing circuitry using a flex circuit. Further, in some examples, the coupling between a bond pad region  715  and the flex circuit  706  can be achieved using a conductive adhesive  704  similar to conductive adhesive  604 , for example. For example, an anisotropic conductive film can be deposited on the bond pad region and/or the flex circuit and an electrical connection can be formed by laminating the two together. 
       FIGS. 7B-7C  illustrate cross-sectional views of touch sensor panel  700  at a location including the connection between a bond pad region  715  and a flex circuit  706 . The touch sensor panel  700  can include one or more components that are included in touch sensor panel  600 , such as substrate  702 , flex circuit  706  (including a conductive portion  706   b  and an insulting portion  706   a ), and conductive adhesive  704 . Similar to  FIGS. 6B-6C , the touch electrodes are not shown in  FIGS. 7B-7C  for ease of illustration. 
     Touch sensor panel  700  can further include one or more conductive traces  722  that wrap around substrate  702  to transfer the one or more touch electrodes disposed on the first side of the substrate to the second side of the substrate. As shown in  FIGS. 7B-7C  for conductive traces  722  can wrap around from the first side (e.g., the top side) of the substrate to the second side (e.g., the bottom side) of the substrate via a third side of the substrate (e.g., the right side illustrated in  FIG. 7B  for example). The third side of the substrate can be between the first side of the substrate and the second side of the substrate (e.g., orthogonal to the first and second sides). A first edge (e.g., top edge) of the first side of the substrate can define a first boundary between the first side of the substrate and the third side of the substrate. A second edge (e.g., bottom edge) of the second side of the substrate can define a second boundary between the second side of the substrate and the third side of the substrate. As shown in  FIGS. 7B-7C , flex circuit  706  can be coupled to the second side (e.g., the bottom side) of the substrate  702 . Thus, in some examples, the conductive trace(s)  722  can be used to couple one or more touch electrodes (e.g., column electrodes  708  illustrated in  FIG. 7A ) on the first side of the substrate  702  to the second side of the substrate for single-sided bonding with the flex circuit  706  on the second side of the substrate. 
     The bond pad region  715  of touch sensor panel  700  can include one or more bond pads, for example. Each of the one or more bond pads can be coupled to a touch electrode (e.g., via routing traces on the second side or via trace transfer from the first side). In some examples, bond pad region  715  can include bond pads that couple to touch electrodes on the first side of the substrate  702  and bond pads that couple to touch electrodes on the second side of the substrate  702 . In some examples, the bond pad and/or routing traces can be formed of the same material as the touch electrodes (e.g., ITO). In some examples, the bond pad and/or routing traces can be formed of a different material (e.g., copper). The conductive adhesive  704  can be disposed over the bond pads and/or over the conductive material  706   b  of the flex circuit  706  for robust mechanical and electrical connection to circuitry, such as touch circuitry (e.g., touch controller  206 ) disposed on a printed circuit board  712 . In some examples, the printed circuit board  712  can be disposed beneath the display/touch screen or in a border region so as not to obscure the display and/or interfere with touch sensing. The flex circuit  706  enables bending of the routing traces between the touch sensor panel substrate  702  and the printed circuit board  712  with the corresponding touch sensing circuitry. 
       FIGS. 7D-7F  illustrate various configurations of a touch sensor panel  700  that includes a conductive trace  722  that wraps around substrate  702  to couple touch electrodes on a first side (e.g., the top) of the substrate to a bond pad region (e.g., bond pad region  715 ) on the second side (e.g., a bottom side) of the substrate in accordance with some examples of the disclosure. For ease of illustration and description, a single touch electrode on a first side of substrate  702  and conductive trace  722  wrapping around substrate  702  are shown in  FIGS. 7D-7F , but it is understood that similar structures can be implemented for trace transfer for multiple touch electrodes (e.g., as shown in  FIG. 7H ). Additionally, for ease of illustration and description, flex circuit  706  is not shown in  FIGS. 7D-7F , but it is understood that flex circuit  706  can be coupled to one or more bond pads and/or conductive traces on the second side of substrate  702  (e.g., touch electrodes on the second side and/or touch electrodes transferred from the first side via conductive traces  722 ). 
     As shown in  FIG. 7D , in some examples, the touch sensor panel  700  includes a first bond pad  716   a  on the first side of the substrate  702  and a second bond pad  716   b  on the second side of the substrate  702 . Both the first bond pad  716   a  and the second bond pad  716   b  can correspond to a first-side touch electrode. For example, touch sensor panel  700  can further include a conductive trace  724  which can represent a touch electrode on the first side of substrate  702  or an electrical connection (e.g., routing) on the first side of substrate  702  between a touch electrode and bond pad  716   a  on the first side of substrate  702 . In some examples, the conductive trace  724  on the first side of the substrate  702  can include a conductive material that can be the same as or different than the touch electrode (e.g., ITO, copper, etc.). In some examples, bond pads  716   a  and/or  716   b  can be metal conductors such as copper (or the like). Conductive trace  722  can wrap around the substrate  702  and can electrically couple bond pad  716   a  and bond pad  716   b . Conductive trace  722  can include a conductive material such as silver or copper. In some examples, the conductive material of conductive trace  722  can be a patterned conductive paste (e.g., silver paste, copper paste, etc.). 
       FIG. 7E  illustrates an alternate configuration of the touch sensor panel  700  using one bond pad rather than two bond pads for trace transfer. As shown in  FIG. 7E , in some examples, touch sensor panel  700  includes a bond pad  716   a  on one side of the substrate  702  coupled to a touch electrode (e.g., by conductive trace  724 ). The touch electrode (and/or its routing to bond pad  716   a ) represented by conductive trace  724  can be transferred by way of the bond pad  716   a  to the second side of substrate  702  via conductive trace  722  (e.g., a conductive metallic paste). In some examples, the touch electrode can be ITO, bond pad  716   a  can be copper and conductive trace  722  can be a silver paste. The conductive trace  722  can wrap around from the first side of substrate  702  to the second side of substrate  702 , without the use of a second bond pad on the second side of substrate  702 . The flex circuit (not shown) can be coupled (e.g., via ACF) to conductive trace  722  on the second side of substrate  702 . Although bond pad  716   a  is illustrated in  FIG. 7E  as being on the first side (e.g., the top side) of substrate  702 , in some examples of trace transfer with one bond pad, the bond pad can be on the second side (e.g., the bottom side) of substrate  702 , with a placement similar to bond pad  716   b  in  FIG. 7D . In such an example, the conductive trace  722  can be coupled directly to conductive trace  724  (e.g., touch electrode and/or its routing) on the first side and wrapped around to a bond pad on the second side of substrate  702 . In some examples, the touch electrode and/or conductive trace  724  can be ITO and conductive trace  722  can be a copper paste. 
       FIG. 7F  illustrates another alternate configuration of the touch sensor panel  700  without bond pads for trace transfer. As shown in  FIG. 7F , touch sensor panel can include a conductive trace  724  representing a touch electrode (e.g., ITO) and or its routing disposed on a first side of substrate  702  that can be electrically coupled to another conductive trace  722  that wraps around the substrate from a first side (e.g., the top side) to a second side (e.g., the bottom side) of substrate  702 , without the use of a bond pads on either side of substrate  702 . The flex circuit (not shown) can be coupled (e.g., via ACF) to conductive trace  722  (e.g., on the second side of substrate  702 ). In some examples where the touch electrode and/or conductive trace  724  includes ITO and conductive trace  724  is coupled to conductive trace  722  without bond pads (e.g.,  716   a  or  716   b ), conductive trace  722  can include copper paste, or another conductive material suitable for coupling with the low sheet resistance of ITO touch electrodes. In some examples, other conductive or semi-conductive materials and/or alloys may be used for conductive trace  724  and/or conductive trace  722  (and for bonding pads). 
     In some examples, conductive traces  722  can connect touch electrodes on a first side of the substrate  702  to a bond pad region  715  on a second side of a substrate  702 , enabling touch sensor panel  700  to include a single bond pad region  715  that includes connections to touch electrodes on both sides of the substrate  702 .  FIGS. 7G-7H  illustrate partial views of the border region of a touch sensor panel  700  that includes a bond pad region  715  for single-sided bonding to a flex circuit on one side of the substrate  702 .  FIGS. 7G-7H  can correspond to trace transfer using two bond pads as described above with respect to  FIG. 7D . The touch sensor panel  700  can include an opaque mask  718  similar to opaque mask  618  differentiating between an active region  720  and a border region of the touch sensor panel  700 . The bond pad region  715  can be included in the border region on a second side of substrate  702 , which can surround an active region that includes touch electrodes and/or display pixels. The bond pad region  715  can include a plurality of bond pads  716   b  connected (via trace transfer techniques) to touch electrodes on the first side of the substrate  702  and a plurality of bond pads  714  connected to touch electrodes on the second side of the substrate  702 . The bond pads  716   a  on the first side of the substrate  702  can be connected to bond pads  716   b  in bond pad region  715  on the second side of the substrate  702  via trace transfer (e.g., via conductive traces  722 ). 
     In some examples, touch electrodes on the first side of substrate  702  can be routed to bond pads  716   a  on the first side of substrate  702 . Bond pads  716   a  on the first side of the substrate can be coupled to bond pads  716   b  on the second side of the substrate conductive traces  722  (e.g., conductive paste). The conductive traces  722  can wrap around the substrate  702  from the first side of the substrate to the second side of the substrate. In this way, the touch electrodes disposed on the first side of the substrate  702  can be connected to bond pads  716   b  on the second side of the substrate  702 . Thus, bond pads  716   b  and bond pads  714  can both be disposed on the same side of the substrate, allowing all of the bond pads  716   b  and  714  to be connected to one flex circuit  706  (e.g., single-sided bonding). 
     As described above with reference to  FIGS. 7A-7H , single-sided bonding at bond pad region  715  can facilitate connections of touch electrodes of a double-sided sensor to a PCB  712  via a flex circuit  706  (e.g., one flex circuit). By including conductive traces  722  that wrap around the substrate  702  from one side to an opposite side, the bond pad region  715  can include connections to touch electrodes on both sides of the substrate  702 , although the bond pad region  715  is on one side of the substrate  702 . As stated above, a single-sided bonding to a flex circuit can increase manufacturing yield, provide a more robust connection structure (damage-resistant), reduce the thickness of the stack-up (enabling the touch screen to be thinner) and shrink the border region (enabling the touch screen to occupy more of the device surface) as compared with the double-sided bonding of multiple flex circuits. For example, fewer bonding steps of fewer flex circuits can simplify manufacturing and improve yield (one bonding step for one flex circuit versus multiple bonding steps for multiple flex circuits). For example, a single flex circuit at a single bonding site can provide a more robust connection (e.g., more points of contact in one region) and debugging or repairing damage can be simplified to a single connection point. For example, a touch sensor panel with a flex circuit on one side can be thinner than a touch sensor panel with a flex circuit on both sides. For example, one bond pad region can reduce the number of ground pads and/or fiducials, as ground pads and/or fiducials may be duplicated for each additional flex circuit connection. Additionally, a single flex circuit connection or fewer flex circuit connections can reduce or eliminate the need for interstitial spacing between bond pad regions. 
     Although trace transfer techniques are discussed above primarily in the context of double-sided touch sensor panels, it should be understood that trace transfer techniques can also be used in the context of a single side of a touch sensor panel. For example, touch electrodes on a first (top) surface of a single-sided touch sensor panel substrate can be routed to a second (bottom) side using trace transfer techniques to enable flex circuit bonding on the second side of the substrate rather than the first side of the substrate (or vis versa). In some examples, trace transfer techniques can be used in a single-sided touch sensor panel to minimize border space. For example, the trace transfer technique can be used to route some touch electrodes from a first side (that includes the touch electrodes) to a second side (that may not include touch electrodes) of the substrate for routing purposes. This can reduce the amount of routing in the border region compared to routing all the traces on the same (first) side of the substrate. The routing traces on the second side of the substrate can then be transferred back to the first side to form a single bond pad region. Alternatively, multiple bond pad regions can be used (e.g., one on a first side of the substrate and one on a second side of the substrate, opposite the first side of the substrate). 
     Referring back to  FIG. 7A , in some examples, PCB  712  on which the touch circuitry may be disposed can be disposed beneath the display/touch screen or in a border region so as not to obscure the display and/or interfere with touch sensing. As a result, in some examples, flex circuit  706  may bend 180 degrees. In some examples, it can be advantageous to reduce the amount that a flex circuit bends (e.g., number of degrees) to connect the touch electrodes of a touch sensor panel to touch circuitry. In some examples, the flex circuit can be bonded perpendicular to the touch sensor panel stack-up (e.g., on a third side perpendicular to the first and second sides) such that the amount of bend can be reduced by 90 degrees. Reducing the amount of bend of a flex circuit can reduce the amount of strain the connection between the bond pads and the flex circuit are subjected to, thereby increasing the reliability and durability of the connection between the touch electrodes of the touch sensor panel and the flex circuit and, therefore, of the touch sensor panel overall. It should be understood that reducing the amount of bend of the flex circuit can be used with or independent from the trace transfer techniques described above with respect to  FIGS. 7B-7H . 
       FIGS. 8A-8C  illustrate exemplary touch sensor panels that include perpendicular bonding of the flex circuit according to some examples of the disclosure. Perpendicular bonding can enable the flex circuit to be disposed on a side surface of the touch sensor stack-up (e.g., parallel to the third side of the substrate) that is perpendicular to the surface of the touch sensor stack-up (e.g., perpendicular to the top surface or bottom surface (first side or second side) of the substrate on which the touch electrodes can be disposed). Orienting the flex circuit in this way can enable the flex circuit to connect the touch electrodes to the touch circuitry with less bending than the amount of bending of the flex circuits included in the touch sensor panels described above with reference to  FIGS. 7B-H  (e.g., 90 degrees of bending rather than 180 degrees of bending). 
       FIG. 8A  illustrates an exemplary touch sensor 800 panel including perpendicular bonding of the flex circuit according to some examples of the disclosure. Touch sensor panel  800  can include substrate  802  and flex circuit  818  oriented perpendicular to the top surface of substrate  802 . In some examples, one or more touch electrodes can be disposed on a (top) surface of substrate  802  (first side of the substrate) and can be connected to one or more bonding pads  804 . For ease of illustration, one bond pad  804  corresponding to one touch electrode is shown. However, it should be understood that touch sensor panel  800  can include additional bond pads (e.g., one bond pad per touch electrode). 
     In some examples, rather than coupling the bond pad to a conductive trace of the flex circuit via an ACF bond (e.g., a direct bond), bond pad  804  can be coupled to flex circuit  818  via an interposer. The interposer can reduce the amount of bend of the flex circuit. In some examples, the interposer can be a printed circuit board with an “L” shape as shown by interposer PCB  814 . For example, the “L” shape interposer PCB  814  can include a first portion parallel to the (top) surface of the substrate  802  on which one or more touch electrodes can be disposed and a second portion perpendicular to the (top) surface of substrate  802 . Interposer PCB  814  can be attached to substrate  802 . For example, interposer PCB  814  can be bonded to substrate  802  with an adhesive  816  (e.g., epoxy). In some examples, the interposer PCB  814  can be bonded to substrate  802  in other ways (e.g., solder bonds, etc.). Although adhesive  816  is shown on the top surface of substrate  802  (first side of substrate  802 ), in some examples, adhesive can be disposed on the third side of substrate  802  (perpendicular to the first side) in addition to or instead of on the top of substrate  802 . 
     Interposer PCB  814  can include bond pads and/or other conductive traces  806  on the surface of the interposer PCB  814  and/or internal to interposer PCB  814  to enable connections to bond pad  804  on the first portion of interposer PCB  804  and to enable connections to flex circuit  818  on the second portion of interposer PCB  804 . In some examples, a trace transfer technique can be used to deposit conductive material (e.g., forming conductive traces, such as conductive trace  810 ) to electrically couple the bond pads of one or more touch electrodes (e.g., bond pad  804 ) to the conductive traces  806  of interposer PCB  814 . For example, bond pad  804  (e.g., in a bond pad region of the touch sensor panel  800 ) can be disposed on the top surface of substrate  802  and can be electrically coupled to a touch electrode. Bond pad trace  804  can include a conductive material, such as an opaque conductive material (e.g., copper, gold, silver, etc.) or a transparent or partially transparent conductive material (e.g., ITO, AZO, etc.). Conductive trace  810  can couple bond pad  804  and conductive trace  806  together, facilitating the electrical coupling of the touch electrodes to interposer PCB  814 . In some examples, conductive trace  810  can be deposited using wire bonding techniques. However, wire bonding can require high temperatures that can cause damage to other components of the touch sensor panel  800 , such as bond pad  804 , substrate  802 , touch electrodes, or other components of the touch sensor panel  800 . Therefore, in some examples, conductive trace  810  can be deposited using an aerosolized conductive material, such as silver or other suitable conductive materials. Aerosol techniques can be performed at relatively low temperatures, thereby protecting the other components of the touch sensor panel  800  during assembly. 
     Conductive trace  806  (representative of multiple traces for routing bond pads to the flex circuit) can be disposed on (and/or in) the interposer PCB  814 . Like the interposer PCB  814 , conductive trace  806  can wrap around the touch sensor panel  800  from a (top) surface that is parallel to the surface of the substrate  802  on which the touch electrodes can be disposed to a surface (e.g., the third side or parallel to the third side) that is perpendicular to the surface on which the touch electrodes can be disposed, for example. 
     As described herein, in some examples, flex circuit  818  can be disposed in a plane perpendicular to (or otherwise intersecting) the plane in which the touch electrodes can be disposed on the (top) surface of substrate  802 . Orienting flex circuit  818  in this way can reduce the bend (e.g., reduce the number of degrees of bend) required by the flex circuit  818  to connect the touch electrodes to touch circuitry located elsewhere (e.g., behind the display) in the electronic device incorporating touch sensor panel  800 . For example, in some situations, a flex circuit can bend a number of degrees on the order of 180 degrees (e.g., 170-190 degrees) in order to connect touch electrodes to touch circuitry behind the display. Interposer PCB  814  and flex circuit  818  included in touch sensor panel  800 , however, can connect the touch electrodes to touch circuitry by flex circuit bending on the order of 90 degrees (e.g., 80-100 degrees). Reducing the amount that flex circuit  818  bends can reduce the amount of strain experienced by the flex circuit. 
     Flex circuit  818  can be electrically coupled to the interposer PCB by way of conductive traces  806  of interposer PCB  814  and conductive traces  808  (formed from a conductive material such as copper, gold, silver, or the like) of flex circuit  818 . In some examples, the electrical connection can also be made by conductive bonding  812  (e.g., a conductive adhesive or other form of bonding material). In some examples, conductive bonding  812  can be electrically coupled to conductive trace  806 . Conductive bonding  812  can be implemented with an anisotropic conductive film or surface mount technology (SMT), for example. 
     As discussed above, conductive trace  806  can be disposed on (and/or in) the interposer PCB  814  such that a portion of conductive trace  806  can be included on the first portion of interposer PCB  814  parallel or substantially parallel to the touch electrodes on the top surface of substrate  802  and a portion of conductive trace  806  can be included on the second portion of interposer PCB  814  perpendicular or substantially perpendicular to the touch electrodes on the top surface of substrate  802 . As described above, conductive trace  806  can be electrically coupled to the touch electrodes via bonding pad  804  and conductive trace  810 . Therefore, connecting the flex circuit  818  to conductive trace  806  on the second portion of interposer PCB  814  can connect flex circuit  818  to the touch electrodes with reduced bend. 
     In some examples, touch sensor panel  800  can further include strain relief  822 . Strain relief can be provided by an adhesive or other suitable material with low stiffness (e.g., less than a threshold Young&#39;s modulus) disposed to carry some of the mechanical load of the bending of the flex circuit (thereby relieving stress concentrations). Strain relief  822  can provide structural and/or mechanical support to the flex circuit  818  at the location of the flex circuit that bends to connect to the touch circuitry, to further reduce strain on the connection between flex circuit  818  and the remaining circuitry (e.g., interposer PCB  814 , etc.). Additionally, touch sensor panel  800  can include an adhesive layer  820  disposed over the touch electrodes, bond pads and conductive traces, for example. The adhesive layer  820  can be an optically clear adhesive and can provide electrical isolation, and mechanical and/or environmental protection, for example. 
     As shown in  FIG. 8A , the touch sensor panel  800  can include a flex circuit  818  that can bend on the order of 90 degrees (e.g., 80-100 degrees) to connect one or more touch electrodes of the touch sensor panel to touch circuitry. Arranging the flex circuit  818  such that it bends about 90 degrees can decrease the strain experienced by the flex circuit compared with a bend of about 180 degrees, thus increasing the durability and reliability of touch sensor panel  800 . 
       FIG. 8B  illustrates an exemplary touch sensor 830 panel including perpendicular bonding of the flex circuit according to some examples of the disclosure. Touch sensor panel  830  can include a substrate  832  (e.g., similar to substrate  802 ), bond pad  834  (e.g., similar to bond pad  804 ), conductive traces  836 ,  838 , and  840  (e.g., similar to conductive traces  806 ,  808 , and  810 ), conductive bonding  842  (e.g., similar to conductive bonding  812 ), interposer PCB  844  (e.g., similar to interposer PCB  814 ), adhesive  846  (e.g., similar to adhesive  816 ), flex circuit  848  (e.g., similar to flex circuit  818 ), adhesive layer  850  (e.g., similar to adhesive layer  820 ), and strain relief  852  (e.g., similar to strain relief  822 ). For brevity the similar description of these components is not repeated here. 
     Touch sensor panel  830  can be similar to the touch sensor panel  800  described above with respect to  FIG. 8A , but in  FIG. 8B , interposer PCB  844  can be bonded to substrate  832  on a (bottom) side (second side) of the substrate opposite from the (top) side (first side) of the substrate including bond pads  834  that can be coupled to the one or more touch electrodes of touch sensor panel  830 . Moving the interposer PCB  844  to the second side of substrate  832  can enable a simplified connection between bond pad(s)  834  and the interposer conductive trace(s)  836  via conductive trace(s)  840 . In some examples, conductive trace  840  can be deposited using an aerosolized conductive material, such as silver. However, in some cases, conductive trace  840  can be formed by depositing the conductive material without the need for aerosolizing the conductive material. 
     Adhering interposer PCB  844  to the (bottom) side of substrate  832  opposite from the (top) side of the substrate including the bond pads can provide more surface area (because the bottom side of substrate  832  does not include bond pads  834 ) for adhesive  846  and enable the use of more of adhesive  846  (e.g., epoxy) for attaching the interposer PCB to the substrate relative to touch sensor panel  800 . Touch sensor panel  800 , for example, can include adhesive  816  and bond pads  804  on the same side of substrate  802 , which results in less surface area for the adhesive to avoid adhesive  816  overlapping bond pads  804 . It can be advantageous to avoid overlapping adhesive  816  with bond pads  804  because the non-conductive adhesive overlapping the bond pad can reduce the area of the bond pad available for electrical contact with conductive traces  810 . 
       FIG. 8C  illustrates an exemplary touch sensor panel  860  including perpendicular bonding of the flex circuit according to some examples of the disclosure. Touch sensor panel  860  can include a substrate  862  (e.g., similar to substrate  802  or  832 ), bond pads  864  (e.g., similar to bond pads  804  or  834 ), conductive traces  870  and  872  (e.g., similar to conductive traces  806 ,  808 ,  810 ,  836 ,  838 , and  840 ), flex circuit  878  (e.g., similar to flex circuit  818  or  848 ), adhesive layer  880  (e.g., similar to adhesive layers  820  or  850 ), strain relief  882  (e.g., similar to strain relief  822  or  852 ). For brevity the similar description of these components is not repeated here. 
     Touch sensor panel  860  can be similar to the touch sensor panel  800  and  830  described above with respect to  FIGS. 8A-8B , but touch sensor panel  860  may not include an interposer PCB (e.g., interposer PCB  814  or  844 ) or may also not include conductive bonding similar to conductive bonding  812  or  842 . Instead, the flex circuit can bonded to the side (e.g., third side) of touch sensor panel  860 , as described in more detail below. 
     Touch sensor panel  860  can be included with a display to form a touch screen. Thus, the touch screen including touch sensor panel  860  can also include a polarizer  884  (for the display) that can be bonded to substrate  862  with an adhesive layer  886 . As shown in  FIG. 8C , flex circuit  878  can be bonded to the touch screen including substrate  862  of the touch sensor panel and polarizer  884  with adhesive  876  (e.g., epoxy). The combined thickness of polarizer  884  and substrate  862  can create sufficient stack-up height to provide surface area for adhesive  886  to support flex circuit  878  without the use of an interposer PCB. In some examples, the thickness of the touch sensor panel may be sufficient and flex circuit  878  can be bonded to substrate  862  without also bonding to polarizer  884 . 
     Bond pad(s)  864 , which can be connected to one or more touch electrodes of touch sensor panel  860 , can be coupled to conductive trace(s)  872  of flex circuit  878  via conductive trace  870 . Conductive trace(s)  870  can include a conductive material (e.g., silver) formed using an aerosol technique, such as the aerosol technique for trace transfer described above with reference to  FIG. 8A . Conductive trace(s)  870  can wrap around from the top side of substrate  862  to the conductive trace(s)  872  of flex circuit  878 . 
     Strain relief  882  (e.g., potting) can be disposed over the conductive trace(s)  870  and/or  872 , and over the flex circuit  878  to reduce the amount of strain experienced by the flex circuit  878 , for example. In some examples, additional strain relief can be provided on the opposite side of flex circuit  878  (e.g., below polarizer  884 ) similar to strain relief provided by strain relief  822  in  FIG. 8A . Bonding flex circuit  878  to the side (third side) of the touch sensor panel as shown in  FIG. 8C  can reduce the bend of the flex circuit on the order of 90 degrees (e.g., 80-100 degrees) to connect the one or more touch electrodes to touch circuitry. 
     Some of the examples described herein include bond pads for use with trace transfer techniques and/or flex circuit bonding.  FIGS. 9A-10C  illustrate exemplary bond pads formed on a substrate according to examples of the disclosure. For example,  FIGS. 9A-9B  illustrate exemplary rectangular bond pads according to examples of the disclosure. As illustrated in the top view of  FIG. 9B  for example, a bond pad region can be disposed on a first (top) side of substrate  902 . The bond pads included in the bond pad region can have a rectangular shape (length L 1  and width W 1 ), among other possible shapes, and can be disposed a distance (D 1 ) from an edge (indicated by the arrow in  FIG. 9B ) of substrate  902 . The distance between the bond pads and the edge of substrate  902  can, for example, provide tolerance for die cutting or other singulation processes. 
       FIG. 9A  illustrates a perspective view of a portion of substrate  902 , bond pad  906  and a transparent conductive material  904 . For example, the touch sensor panel can be formed using a substrate (e.g., cyclo olefin polymer (COP), PET, polycarbonate (PC) or other suitable material) overlaid on a first side with one or more layers of transparent (or partially transparent) conductive material (e.g., ITO) and/or one or more layers of non-transparent conductive material (e.g., copper). In some examples, the overlaid conductive layers can be mirrored on the second side of the substrate. For ease of illustration and description one ITO layer and one copper layer on one side of a substrate are shown in  FIG. 9A , but it is understood that additional or different layers can be disposed on one or both sides of the substrate. During a fabrication step, the copper between the edge of substrate  902  and bond pad  906  can be etched away to form bond pad  906  (e.g., to define the boundary of bond pad  906  proximate to the edge of substrate  902 ). Removing the copper between the edge of substrate  902  and bond pad  906  can enable singulation techniques to be applied to the edge of substrate  902  without cutting through copper. The fabrication step can etch copper without etching the underlying ITO layer  904 . As a result, bond pad  906  can be electrically contacted from the edge of substrate  902  via the ITO layer  904  during fabrication/assembly (e.g., to avoid electrostatic discharge (ESD) events or other electrical stress events). During a subsequent fabrication step, trace transfer techniques can be used dispose a conductive trace  922  to route bond pad  906  off of the first side of the substrate (e.g., for connection to a flex circuit on the second or third side of the substrate as described herein). As described herein, in some examples, the conductive trace  922  can be a silver paste (or other suitable material). 
       FIGS. 10A-10B  illustrate exemplary bond pads including a tail portion according to examples of the disclosure. Unlike the rectangular bond pads of  FIG. 9A-9B , bond pads in the bond pad region disposed on a first (top) side of substrate  1002  can include tail portion  1006 A extending from the rectangular portion of bond pad  1006 . The tail portion  1006 A can extend to the edge of substrate  1002 . The rectangular portion of bond pad  1006  can have dimensions including length L 1  and width W 1 . The tail portion of the bond pads included in the bond pad region can also have a rectangular shape (length L 2  (e.g., the same dimension as D 1 ) and width W 2 ). The tail portion  1006 A of bond pad  1006  can be narrower (e.g., within a threshold distance from the edge) than a rectangular portion of bond pad  1006  (e.g., outside the threshold distance from the edge), such that W 2 &lt;W 1 . The shape of the bond pad and/or tail can be different than the rectangular shapes illustrated in  FIGS. 10A-10B . Some other exemplary possibilities are illustrated in  FIG. 10C , described below in more detail. 
     The rectangular portion of the bond pads can be disposed a distance (D 1 ) from an edge (indicated by the arrow in  FIG. 10B ) of substrate  1002 . The distance between the bond pads and the edge of the substrate  1002  can for example, provide tolerance for die cutting or other singulation process. The width W 2  of tail portion  1006 A of bond pad  1006  can be less than W 1  such that the conductive material (e.g., copper) may be cut using singulation techniques. In some examples, W 2 , can be less than a threshold amount (e.g., &lt;10 microns) to enable cutting using singulation techniques. 
     In some examples, the dimensions of the rectangular portion of the bond pads in  FIG. 10B  and the rectangular bond pads in  FIG. 9B  can be the same dimensions (e.g., W 1  and L 1  can be the same values in both  FIGS. 9B and 10B ). In some examples, the dimension of the rectangular portion of the bond pads in  FIG. 10B  and the rectangular bond pads in  FIG. 9B  can be different dimensions (e.g., W 1  and/or L 1  can be different values in  FIG. 9B  as compared with  FIG. 10B ). In some examples, due to the addition of the tail portion  1006 A, the dimensions of the rectangular portion of bond pads  1006  can be reduced compared with the dimensions of rectangular bond pads  906  (e.g., due to the increased contact area provided by the tail portion  1006 A). In some examples, by reducing the size of the rectangular portion of the bond pads (e.g., by reducing L 2 ), the bond pad region (and the border region) can be reduced and more of the touch sensor panel substrate area can be used for the active region. 
       FIG. 10A  illustrates a perspective view of a portion of substrate  1002 , bond pad  1006  including tail portion  1006 A, and a transparent conductive material  1004 . For example, the touch sensor panel can be formed using from a substrate with overlaid conductive layers as described with respect to  FIG. 9A . During a fabrication step, the copper and ITO between the edge of substrate  1002  and bond pad  1006 , excluding the copper and ITO of tail portion  1006 A, can be etched away to form bond pad  1006  including tail portion  1006 A. Reducing the width of the tail portion can enable singulation techniques despite the presence of some copper at the edge. Unlike the formation of bond pad  906  using a fabrication step that can etch copper without etching the underlying ITO layer, the formation of bond pad  1006  including tail portion  1006 A can use a fabrication step that can etch both copper and the underlying ITO layer. In some examples, the fabrication step etching both copper and ITO can be earlier in the fabrication process than the fabrication step etching copper without etching ITO. As a result, the earlier fabrication process can reduce tolerance related errors by defining a feature of bond pad  1006  (e.g., to define the boundary of bond pad  1006  proximate to the edge of substrate  1002 ) in an earlier step (e.g., due to mismatch tolerances between different masking steps). The tail portion  1006 A also provides access for electrically contacting bond pad  1006  from the edge of the substrate during fabrication (e.g., to avoid ESD or other electrical stress events). 
     During a subsequent fabrication step, trace transfer techniques can be used dispose a conductive trace  1022  to route bond pad  1006  off of the first side of the substrate (e.g., for connection to a flex circuit on the second or third side of the substrate as described herein). As described herein, in some examples the conductive trace  1022  can be a silver paste (or other suitable material). In some examples, conductive trace  1022  can overlap tail portion  1006 A entirely. For example, a conductive trace of silver entirely overlapping the tail portion  1006 A formed of copper can provide corrosion protection for the copper tail portion, as the silver may be less chemically active. Additionally, the silver can be self-passivating. In some examples, conductive trace  1022  can at least partially overlap the rectangular portion of bond pad  1006  (e.g., as shown in  FIG. 10B ) to provide an electrical connection for trace transfer. In some examples, conductive trace  1022  may not overlap the rectangular portion of the bond pad  1006  at all, and the electrical connection can be provided by the overlap of the conductive trace and the tail portion  1006 A. 
     It should be understood that although  FIG. 9B  and  FIG. 10B  respectively illustrate a bond pad region including uniform bond pads, that the bond pads need not be uniform. In some examples, one or more of the bond pads (at least one) could be a rectangular bond pad  906  as illustrated in  FIG. 9B . In some examples, one or more of the bond pads (at least one) could include a bond pad  1006  including a rectangular portion and a tail portion  1006 A. Additionally, it should be understood that although  FIGS. 9A-10B  illustrate bond pads with a rectangular shape (with or without a rectangular tail portion), the shape of one or more of the bond pads and/or the shape of the tail can be different. For example,  FIG. 10C  illustrates some shapes for bond pads including a tail portion according to examples of the disclosure. For reference,  FIG. 10C  includes bond pad  1006  including a rectangular portion and tail portion  1006 A with a rectangular shape. In some examples, the width of bond pad  1016  can taper in the tail portion  1016 A from the rectangular portion in a series of steps. For example, the width W 1  of the bond pad in the rectangular portion can gradually narrow in steps to W 2 , W 3  and ultimately W 4  (where W 1 &gt;W 2 &gt;W 3 &gt;W 4 ). Although three steps are shown for bond pad  1016 , it should be understood that more (e.g., 4, 10, etc.) or fewer (e.g., 2) steps are possible. In some examples, the bond pad  1026  can taper linearly in the tail portion  1026 A from the rectangular portion. For example, the width W 1  of the bond pad in the rectangular portion can narrow linearly from W 1  to W 2  (where W 1 &gt;W 2 ). Although linear steps or a linear taper are shown in  FIG. 10C , the steps or taper may be non-linear in some examples. For example, bond pad  1036  can taper non-linearly in the tail portion  1036 A from the rectangular portion. For example, the width W 1  of the bond pad in the rectangular portion can narrow non-linearly (with a curvature) from W 1  to W 2  (where W 1 &gt;W 2 ). 
     For ease of illustration and description  FIGS. 9A-10C  illustrate bond pads on one side of a substrate. It is understood that bond pads can be formed on the second side of the substrate. For example,  FIGS. 10A-10B  illustrate a bond pad  1006  formed on the first (top) side of the substrate with a tail portion  1006 A extending to a first (top) edge of the substrate. In a similar manner, a bond pad can be formed on the second (bottom) side of the substrate with a tail portion extending to a second (bottom) edge of the substrate. Trace transfer techniques described herein can be used to deposit a conductive trace (e.g., silver paste) to connect the bond pad on the first side of the substrate to the bond pad on the second side of the substrate. The conductive trace can wrap around the first (top) edge of the substrate, the third side, and the second (bottom) edge of the substrate. 
     As described herein, the trace transfer techniques can include wrapping one or more conductive traces around the substrate (e.g., as illustrated by conductive trace(s)  722  in  FIGS. 7B-7H ) or off the substrate (e.g., as illustrated by conductive traces  810 ,  840 ,  870  in  FIGS. 8A-8C ). In some examples, the thickness and/or width of the conductive traces can be increased to provide increased structural stability. For example, the thickness and/or width of the conductive traces can be increased at or near edges of the substrate (e.g., at a first distance from an edge) where defects, such as burrs, may be more likely to occur (e.g., during a singulation process). The thickness and/or width of the conductive traces at or near the bond pads (e.g., at a second distance from the edge, greater than the first distance) can be less than the thickness and/or width of the conductive traces at or near the edges. As another example, the thickness and/or width of the conductive traces can be increased in areas where the of the conductive traces change direction (e.g., 90 degree turns or other changes in direction greater than a threshold number of degrees). For example, the conductive trace(s)  722  in  FIGS. 7B-7H  include two 90 degree turns at the top and bottom edge of the substrate that can make the conductive traces brittle or structurally weak. Likewise, conductive trace  810  in  FIG. 8A  can include two 90 degree turns from the substrate up to interposer  814 . 
       FIGS. 11A-11D  illustrate exemplary touch sensor panels including conductive traces with variable thickness according to examples of the disclosure.  FIG. 11A  illustrates a touch sensor panel  1100  with uniform thickness (T 1 ) for the conductive trace  1122  between first bond pad  1106 A and first (top) edge  1101  of substrate  1102 , between second bond pad  1106 B and second (bottom) edge  1103  of substrate  1102 , and between first (top) edge  1101  of substrate  1102  and second (bottom) edge  1103  of substrate  1102 . Although shown as a uniform thickness, in some examples, the thickness of conductive trace  1122  on the first side, second side and/or third side can be different from one another, but may be uniform for the respective side. For example, the thickness of conductive trace  1122  between first bond pad  1106 A and first (top) edge  1101  can be a first thickness (T 1 ), the thickness of conductive trace  1122  between second bond pad  1106 B and second (bottom) edge  1103  can be a second thickness (T 2 ), and thickness of conductive trace  1122  between first (top) edge  1101  and second (bottom) edge  1103  can be a third thickness (T 3 ), where T 1 , T 2 , and T 3  can be different. Although conductive trace  1122  is shown on wrapping around (on three sides of substrate  1102 ), it is understood that the conductive trace may be implemented on fewer than all illustrated sides. 
     In some examples, additional conductive material can be deposited near the edges of the substrate. In some examples, the conductive material can be added in one or more steps to achieve the desired thicknesses for the conductive trace. In some examples, the conductive material can be added in multiple deposition steps (e.g., a first deposition step can add a uniform thickness for the conductive trace and a second deposition step can add additional thickness at the edges/corners).  FIG. 11B  illustrates a touch sensor panel  1110  with a non-uniform thickness for conductive trace  1132  between first bond pad  1106 A and first (top) edge  1101  of substrate  1102 , between second bond pad  1106 B and second (bottom) edge  1103  of substrate  1102 , and between first (top) edge  1101  and second (bottom) edge  1103 . For example, the thickness of conductive trace  1132  between first bond pad  1106 A and first edge  1101  can increase (e.g., in a linear or non-linear step) from a first thickness (T 1 ) at or near bond pad  1106 A to a second thickness (T 2 ) at or near first edge  1101 . The thickness of conductive trace  1132  between second bond pad  1106 B and second edge  1103  can increase from a first thickness (T 1 ) at or near bond pad  1106 B to a second thickness (T 2 ) at or near second edge  1103 . The thickness of conductive trace  1132  between first edge  1101  and second edge  1103  can be a first thickness at or near a midpoint between edges  1101  and  1103  on the third side, and can increase to a second thickness (T 2 ) at or near edges  1101  and  1103 . Although thicknesses of conductive trace  1132  are shown to increase in a similar manner on the first, second and third sides in  FIG. 11B , it should be understood that the increases may occur on fewer sides and the thickness and/or increases in thickness may be different on each side. For example, the thickness of conductive trace  1132  on the third side between edges  1101  and  1103  can be of a uniform thickness T 2  (unlike the illustration including a step down to thickness T 1  at or near the midpoint of the third side). In some examples, the maximum thickness of the conductive trace on the third side can be greater than the maximum thickness on the first or second sides at or near edges  1101  and  1103 . In some examples, the maximum thickness of the conductive trace on the first and/or second sides at or near edges  1101  and  1103  can be greater than the maximum thickness on the third side. 
       FIG. 11C  illustrates a touch sensor panel  1120  with a non-uniform thickness for conductive trace  1142  between first bond pad  1106 A and first edge  1101 , between second bond pad  1106 B and second edge  1103 , and between first edge  1101  and second edge  1103 . In  FIG. 11C , the increase in thickness of conductive trace  1142  at or near edges  1101  and  1103  compared with the thickness of conductive trace  1142  at or near the bond pads  1106 A,  1106 B can occur via multiple linear or non-linear steps. For example,  FIG. 11B  illustrates one step from thickness T 1  to T 2 .  FIG. 11C  illustrates two steps from thickness T 1  to T 2  to T 3 . Additional steps are possible in other examples. 
       FIG. 11D  illustrates a touch sensor panel  1130  with a non-uniform thickness for conductive trace  1152  between first bond pad  1106 A and first edge  1101  and between second bond pad  1106 B and second edge  1103 . The increase in thickness can be linear (sloping rather than stepping). For example, the thickness can increase from a first thickness T 1  near bond pad  1006 A to a thickness T 2  at or near first edge  1101 . The increase is shown by linear slope  1118 . The increase in thickness of conductive trace  1152  can be similar on the second side of substrate  1102 . In other words, the thickness of conductive material  1152  can taper linearly from a thickness T 2  at or near the edges to a thickness T 1  at or near the bond pads (e.g., as the distance to the first edge of the increases). Although a linear increase (or a linear taper) is illustrated in  FIG. 11D , it should be understood that a non-linear increase (or taper) could be used instead. 
     In some examples, the added conductive material can increase the thickness of the conductive trace such that the thickness at the edge of the substrate (e.g., measured from the first side or third side) is greater than 5 microns, so as to provide improved structural stability. In some examples, the thickness at the edge of the substrate can be between 1-10 microns to provide improved structural stability. 
     The above description of varying thicknesses of the conductive traces with respect to  FIGS. 11A-11D  primarily focuses on the portion of the conductive traces between the bond pad and an edge or between the first and second edges (e.g., the third side). As shown in  FIGS. 11A-11D , the conductive traces (e.g., conductive traces  1122 ,  1132 ,  1143 ,  1152 ) can also, in some examples, at least partially overlap the bond pad (e.g., to form an electrical connection for routing). In some examples, the thickness from top of the conductive trace to the substrate (including the intervening bond pad) can have a thickness T 1  equal to the thickness at or near, but not overlapping, the bond pad. In some examples, the thickness of the conductive trace overlapping the bond pad can be less than 20 microns to enable proper electrical contact between the bond pad and the flex circuit during bonding (e.g., ACF bonding). In some examples, the thickness of the conductive trace overlapping the bond pad can be between 5-15 microns. In some examples, the thickness of the conductive trace overlapping the bond pad can be between 1-10 microns. 
       FIG. 12  illustrates exemplary conductive traces with variable width according to examples of the disclosure.  FIG. 12  includes four exemplary configurations  1200 ,  1210 ,  1220  and  1230  with conductive traces  1204 ,  1214 ,  1224 , and  1234  routed from bond pads  1202 ,  1212 ,  1222 , and  1232  to the substrate edge (indicated by an arrow in  FIG. 12 ). The conductive traces can be wrapped around (e.g., to a second side) or otherwise routed off of the substrate to touch sensing circuitry. For ease of description and illustration, one side (e.g., the first (top) side) is shown, but it should be understood that the width of the traces can be increase near the edges for other sides (the second (bottom) side and/or the third side). 
     For reference,  FIG. 12  includes configuration  1200  including bond pad  1202  and conductive trace  1204  (e.g., corresponding to bond pad  906  and conductive trace  922 ). Conductive trace  1204  can have a uniform width from bond pad  1202  to the edge of the substrate. In some examples, the width of the conductive trace can be increased to improve structural stability. In some examples, the width of the conductive trace can increase linearly from the bond pad to the edge. For example, configuration  1210  illustrates a linear increase for conductive trace  1214  from width W 1  at or near bond pad  1212  to W 2  at or near the edge. In other words, conductive trace  1214  can taper from W 2  at or near the edge to W 1  at or near the bond pad (e.g., as the distance to the first edge of the substrate increases). In some examples, the increase (or taper) can be non-linear. For example, configuration  1220  illustrates a non-linear increase for conductive trace  1224  from width W 1  at or near bond pad  1222  to W 2  at or near the edge. In some examples, the increase can be step-wise, such that each step increases (or narrows from the tapering perspective) the width from one width to another width. For example, configuration  1230  illustrates two step increase for the conductive trace  1234  from width W 1  at or near bond pad  1232  to W 2  to W 3  at or near the edge (where W 3 &gt;W 2 &gt;W 1 ). The number of steps can be greater than ( 3 ,  5 , etc.) or less than (e.g.,  1 ) the two steps illustrated in configuration  1230  in  FIG. 12 . 
     Although varying thickness/width of the conductive trace are shown separately in  FIGS. 11-12 , it is understood that both the thickness and width can vary for the conductive trace. For example, the width of the conductive trace can increase at or near the edge as shown in configuration  1220  of  FIG. 12  and the thickness of the conductive trace can increase at or near the edge as shown in touch sensor panel  1130  in  FIG. 11D . Additionally, although  FIGS. 11 and 12  illustrate bond pads as shown in  FIGS. 9A-9B  (without a copper tail to the edge of the substrate) it should be understood that similar principles of  FIGS. 11-12  can be applied for conductive traces overlaid over bond pads with a tail portion as shown in  FIGS. 10A-10C . 
     Although the terms bond pad or bond pads are used herein to refer to conductive region(s) representing the signal terminus of touch electrode(s) in or near the border region, it should be understood that in some examples, as described herein, a bond to a flexible circuit (e.g., via ACF bonding) may ultimately not be made to the bond pad(s). For example, the flex circuit bond may be made on one side of the substrate leaving the bond pads on the opposite side without a flex circuit bond. In some examples, a bond pad without a flex circuit bond may be referred to a terminus or signal terminus of a touch electrode. 
     Therefore, according to the above, some examples of the disclosure are directed to a touch sensor panel. The touch sensor panel can comprise a substrate including a first side and a second side, a first plurality of touch electrodes formed on the first side of the substrate, a second plurality of touch electrodes formed on the second side of the substrate opposite the first side of the substrate, and conductive traces configured to route the first plurality of touch electrodes from the first side of the substrate around one or more edges of the substrate (e.g., around a first edge defining a boundary of the first side of the substrate, and around a second edge defining a boundary of the second side, and around a third side of the substrate between the first side and the second side) to the second side of the substrate. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch sensor panel can further comprise a first plurality of bond pads formed on the first side of the substrate coupled to the first plurality of touch electrodes and a second plurality of bond pads formed on the second side of the substrate coupled to the second plurality of touch electrodes. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch sensor panel can further comprise a third plurality of bond pads formed on the second side of the substrate coupled to the first plurality of touch electrodes via the conductive traces. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch sensor panel can further comprise a flex circuit bonded to the second side of the substrate coupled to the first plurality of touch electrodes via the conductive traces and coupled to the second plurality of touch electrodes. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the first plurality of touch electrodes and the second plurality of touch electrodes can be formed from a semiconductor material. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the semiconductor material can be indium tin oxide. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the conductive traces can be formed from a metallic paste. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the metallic paste can be a silver paste. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the metallic paste can be a copper paste. 
     Some examples of the disclosure are directed to a method of fabricating a touch sensor panel. The method can comprise forming a first plurality of touch electrodes on a first side of a substrate of the touch sensor panel; forming a second plurality of touch electrodes on a second side of the substrate of the touch sensor panel; and forming conductive traces configured to route the first plurality of touch electrodes from the first side of the substrate around one or more edges of the substrate to the second side of the substrate. 
     Some examples of the disclosure are directed to a touch sensor panel. The touch sensor panel can comprise a substrate, a plurality of touch electrodes disposed on a first surface of the substrate, and a flex circuit coupled to the substrate and oriented perpendicular to the first surface of the substrate. The flex circuit can include one or more conductive traces coupled to the plurality of touch electrodes. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch sensor panel can further comprise: a PCB, the PCB having a first portion parallel to the first surface of the substrate and a second portion perpendicular to the first surface of the substrate. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the first portion of the PCB can be bonded to the first surface of the substrate with an adhesive. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the first portion of the PCB can be bonded to a second surface of the substrate with an adhesive, the second surface of the substrate opposite the first surface of the substrate. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch sensor panel can further comprise conductive bonding disposed between the PCB and the flex circuit that electrically and mechanically couples the flex circuit to the PCB. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch sensor panel can further comprise a strain relief coupled to the flex circuit. Additionally or alternatively to one or more of the examples disclosed above, in some examples, at least part of the one or more conductive traces are disposed between the flex circuit and the strain relief. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch sensor panel can further comprise: a plurality of bond pads coupled to the plurality of touch electrodes; one or more conductive traces configured to wrap around from the first surface of the substrate to electrically couple the plurality of bond pads to the one or more conductive traces of the flex circuit; and potting including a first section disposed parallel to a plane of the first surface of the substrate and a second section disposed perpendicular to the first surface of the substrate. At least part of the one or more conductive traces configured to wrap around from the first surface can be disposed between the flex circuit and the potting. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch sensor panel can further comprise an optical polarizer, the optical polarizer coupled to a second surface of the substrate opposite the first surface of the substrate. The flex circuit can be coupled to the substrate and the optical polarizer via an adhesive. 
     Some examples of the disclosure are directed to a method of forming a touch sensor panel. The method can comprise forming a plurality of touch electrodes on a first surface of a substrate; and coupling a flex circuit to the substrate, the flex circuit oriented perpendicular to the first surface of the substrate, the flex circuit including one or more conductive traces coupled to the plurality of touch electrodes. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method can further comprise forming the one or more conductive traces between the plurality of touch electrodes and the one or more conductive traces of the flex circuit by applying an aerosolized conductive material to the touch sensor panel. 
     Some examples of the disclosure are directed to a touch sensor panel comprising a substrate including a first side and a second side; bond pads formed on the first side of the substrate coupled to touch electrodes formed on the first side of the substrate, at least one bond pad of the bond pads formed on the first side of the substrate extends to a first edge of the substrate; and conductive traces routing the bond pads formed on the first side of the substrate off of the first side of the substrate. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch sensor panel can further comprise bond pads formed on the second side of the substrate coupled to touch electrodes formed on the second side of the substrate opposite the first side of the substrate. At least of one of the bond pads formed on the second side of the substrate can extend to a second edge of the substrate. The conductive traces can route the bond pads formed on the first side of the substrate off of the first side of the substrate around the first edge of the substrate and around the second edge of the substrate to the second side of the substrate. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a first portion of the at least one bond pad formed on the first side of the substrate within a threshold distance from the first edge of the substrate can be narrower than a second portion of the at least one bond pad formed on the first side of the substrate outside the threshold distance from the first edge. Additionally or alternatively to one or more of the examples disclosed above, in some examples, at least one conductive trace of the conductive traces can overlap the first portion within the threshold distance from the first edge of the substrate. Additionally or alternatively to one or more of the examples disclosed above, in some examples, at least one conductive trace of the conductive traces can overlap some, but not all, of the second portion outside the threshold distance from the first edge of the substrate. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a width of the at least one bond pad formed on the first side of the substrate can taper as a distance to the first edge of the substrate decreases. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the taper can include a first step and a second step. The first step can narrow the width by a first amount and the second step can further narrow the width by a second amount. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the bond pads can be formed from copper and the conductive traces can be formed from silver paste. 
     Some examples of the disclosure are directed to a touch sensor panel comprising a substrate including a first side and a second side, bond pads formed on the first side of the substrate coupled to touch electrodes formed on the first side of the substrate, and conductive traces routing the bond pads formed on the first side of the substrate off of the first side of the substrate. A first thickness of at least one conductive trace of the conductive traces at a first distance from a first edge can be greater than a second thickness of the at least one of the conductive trace at a second distance from the first edge, the second distance greater than the first distance. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a first width of the at least one conductive trace at the first distance from the first edge can be greater than a second width of the at least one of the conductive trace at the second distance from the first edge. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a width of the at least one conductive trace can taper as a distance to the first edge of the substrate increases. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the taper can include a first step and a second step. The first step can narrow the width by a first amount and the second step can further narrow the width by a second amount. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a thickness of the at least one conductive trace can taper as a distance to the first edge of the substrate increases. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the taper can include a first step and a second step. The first step can narrow the thickness by a first amount and the second step can further narrows the thickness by a second amount. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a thickness of the at least one conductive trace disposed on a third side of the substrate between the first edge of the substrate and a second edge of the substrate can be greater than the thickness of the conductive trace on the first side of the substrate at or near at least one bond pad of the bond pads. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a thickness of the at least one conductive trace overlapping at least one bond pad of the bond pads can be less than 20 microns. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a thickness of the at least one conductive trace at the first edge can be greater than 5 microns. Additionally or alternatively to one or more of the examples disclosed above, in some examples, at least one bond pad of the bond pads can be formed of copper and the copper of the at least one bond pad terminates a threshold distance from the first edge of the substrate. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the conductive traces can route the bond pads formed on the first side of the substrate off of the first side of the substrate around the first edge of the substrate and around a second edge of the substrate to the second side of the substrate. 
     Some examples of the disclosure are directed to a touch sensor panel. The touch sensor panel can comprise: a substrate; touch electrodes disposed on a first surface of the substrate; and a flex circuit coupled to the substrate and oriented perpendicular to the first surface of the substrate. The flex circuit can include conductive traces coupled to the touch electrodes. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch sensor panel can further comprise: a PCB. The PCB can have a first portion parallel to the first surface of the substrate and a second portion perpendicular to the first surface of the substrate. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the PCB can comprise conductive traces routed from the first portion of the PCB to the second portion of the PCB. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the first portion of the PCB can be bonded to the first surface of the substrate with an adhesive. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the first portion of the PCB can be bonded to a second surface of the substrate with an adhesive, the second surface of the substrate opposite the first surface of the substrate. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch sensor panel can further comprise: conductive bonding disposed between the second portion of the PCB and the flex circuit that electrically and mechanically couples the flex circuit to the PCB. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch sensor panel can further comprise: a strain relief coupled to the flex circuit and coupled to the PCB. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch sensor panel can further comprise: bond pads formed on the first surface of the substrate and coupled to the touch electrodes. The conductive traces of the flex circuit can be coupled to the touch electrodes via the bond pads. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch sensor panel can further comprise: conductive traces configured to couple the bond pads to the conductive traces of the flex circuit. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the conductive traces configured to couple the bond pads to the conductive traces of the flex circuit can be formed from a metallic paste. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the metallic paste can be a silver paste. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the metallic paste can be a copper paste. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the conductive traces configured to couple the bond pads to the conductive traces of the flex circuit can wrap around from the first surface of the substrate to the flex circuit oriented perpendicular to the first surface of the substrate. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch sensor panel can further comprise: potting including a first section disposed parallel to a plane of the first surface of the substrate and a second section disposed perpendicular to the first surface of the substrate. At least part of the conductive traces configured to couple the bond pads to the conductive traces of the flex circuit can be disposed between the flex circuit and the potting. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a first thickness of at least one conductive trace of the conductive traces configured to couple the bond pads to the conductive traces of the flex circuit at a first distance from a first edge of the substrate can be greater than a second thickness of the at least one of the conductive trace at a second distance from the first edge, the second distance greater than the first distance. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a first width of the at least one conductive trace at the first distance from the first edge can be greater than a second width of the at least one of the conductive trace at the second distance from the first edge. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a thickness of the at least one conductive trace overlapping at least one bond pad of the bond pads can be less than 20 microns. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch sensor panel can further comprise: an optical polarizer, the optical polarizer coupled to a second surface of the substrate opposite the first surface of the substrate. The flex circuit can coupled to the substrate and the optical polarizer via an adhesive. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch electrodes can be formed from indium tin oxide (ITO). 
     Although the disclosed examples have been fully described with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of the disclosed examples as defined by the appended claims.

Metadata:
Filing Date: 20191023
Publication Date: 20210914
Grant Date: 20210914
Priority Date: 20181101
Inventors: RAHMANI, HELIA
SHARMA, Prithu
SCHULTZ, DAVID SHELDON
Assignee: APPLE INC
CPC Classifications: [{"code": "H05K1/117", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/04164", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04103", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/0277", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/10121", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0412", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K2201/10962", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/04144", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0448", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/092", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/361", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K2201/09381", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/041662", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K2201/0326", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/147", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0412", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/323", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04108", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04103", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04103", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/111", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04103", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04108", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/111", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/10121", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0277", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/0326", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/092", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 70458558