PATENT DOCUMENT

Publication Number: US-10185446-B2
Application Number: US-90602510-A
Country: US
Kind Code: B2

Title: Touch sensor arrays with integrated inter-layer contacts

Abstract:
Touch pad structures are provided that gather touch sensor data. The data may be used to control a computer or other electronic device. The touch pad structures may be integrated into a computer or other computing equipment or may be provided as a stand-alone accessory. The touch pad structures may include a touch sensor array. The touch sensor array may include rows and columns of touch sensor electrodes, interconnect lines, and other conductive structures. The conductive structures on the touch sensor array may be formed from patterned layers of ink. Interconnect line segments in different layer of ink may be connected in rectangular contact regions. The touch sensor array may have a tail. A layer of insulator may be removed from the substrate across a tip portion of the tail to allow the line segments to be connected.

Claims:
What is claimed is: 
     
       1. A touch sensor array, comprising:
 a substrate having a sensor array region and a tail that extends from the sensor array region; and 
 conductive touch sensor structures on the substrate, wherein at least some of the conductive touch sensor structures are formed in the sensor array region and at least some of the conductive touch sensor structures form parallel interconnect lines in the tail; 
 wherein at least one of the conductive touch sensor structures comprises first and second layers of conductive material in the tail having substantially the same widths at a contact region at which the first and second layers overlap and electrically contact each other, the widths at the contact region having substantially the same width as at least a portion of the second layer of conductive material outside the contact region, and wherein the tail has a tip region that is uncovered by a layer of insulator. 
 
     
     
       2. The touch sensor array defined in  claim 1  wherein the first and second layers of conductive material have a common longitudinal axis. 
     
     
       3. The touch sensor array defined in  claim 2  wherein the substrate comprises a flexible polymer. 
     
     
       4. The touch sensor array defined in  claim 3  wherein the first and second layers of conductive material comprise conductive ink. 
     
     
       5. The touch sensor array defined in  claim 3  wherein the conductive ink comprises screen printed silver ink. 
     
     
       6. The touch sensor array defined in  claim 1  wherein the first layer of conductive material comprises a lower layer of conductive ink and wherein the second layer of conductive material comprises an upper layer of conductive ink. 
     
     
       7. The touch sensor array defined in  claim 1  wherein at least another of the parallel interconnect lines is formed exclusively from a lower layer of conductive ink. 
     
     
       8. The touch sensor array defined in  claim 1  wherein the contact region is rectangular. 
     
     
       9. The touch sensor array defined in  claim 8  wherein the parallel interconnect lines each have a respective width and wherein at least one of the parallel interconnect lines has a width-changing step at which the width of that parallel interconnect line changes. 
     
     
       10. The touch sensor array defined in  claim 1  wherein the parallel interconnect lines each have a respective width and wherein at least one of the parallel interconnect lines has a width-changing step at which the width of that parallel interconnect line changes. 
     
     
       11. The touch sensor array defined in  claim 1  wherein the substrate comprises polyethylene terephthalate. 
     
     
       12. The touch sensor array defined in  claim 1  wherein the tail has a rectangular shape. 
     
     
       13. A touch sensor array, comprising:
 a substrate having a sensor array region and a tail; 
 conductive interconnect lines formed on the substrate from a patterned upper conductive ink layer and a patterned lower conductive ink layer; and 
 a layer of insulator, wherein some of the layer of insulator is interposed between the patterned upper conductive ink layer and the substrate and wherein some of the layer of insulator is interposed between the patterned upper conductive ink layer and the patterned lower conductive ink layer, and wherein at least one conductive interconnect line includes a contact region in the tail in which an upper line segment formed from the patterned upper conductive ink layer has substantially the same width as the patterned lower conductive ink layer and overlaps and electrically contacts a lower line segment formed from the patterned lower conductive ink layer, the width at the contact region having substantially the same width as at least a portion of the patterned upper conductive ink layer formed in the tail but outside the contact region. 
 
     
     
       14. The touch sensor array defined in  claim 13  wherein the substrate has a rectangular portion with four edges and wherein the tail is rectangular and protrudes from one of the four edges. 
     
     
       15. The touch sensor array defined in  claim 14  wherein the contact region is rectangular and wherein the layer of insulator has a straight edge that extends across at least some of the tail. 
     
     
       16. The touch sensor array defined in  claim 15  wherein the conductive interconnect lines have widths and contain width-changing steps at which the widths change and wherein at least some of the width-changing steps are located on the tail. 
     
     
       17. An apparatus, comprising:
 a substrate having a tail; 
 an upper patterned ink layer; 
 a lower patterned ink layer; and 
 an insulating layer, wherein at least some of the lower patterned ink layer touches the substrate, wherein at least some of the insulating layer is interposed between the upper patterned ink layer and the lower patterned ink layer, wherein at least some of the upper patterned ink layer touches the substrate, wherein the upper patterned ink layer comprises a plurality of first interconnect line segments, wherein the lower patterned ink layer comprises a plurality of second interconnect line segments, wherein each of the first interconnect line segments electrically contacts a respective one of the second interconnect line segments in a respective contact region in the tail at which the first and second interconnect line segments have substantially the same width as a portion of the first interconnect line segment formed in the tail but outside the contact region, and wherein the substrate is free of the insulating layer between at least a portion of the second interconnect line segments.

Description:
BACKGROUND 
     This relates to touch sensors, and more particularly, to techniques for forming touch sensor arrays for touch sensors in electronic devices. 
     Electronic devices such as portable computers and touch pads include touch sensors arrays. Many touch sensor arrays are based on capacitive touch electrodes that are arranged in intersecting rows and columns. When the finger of a user or other external object is brought into the vicinity of the touch electrodes, resulting capacitance changes can be detected. This allows the row and column position of the finger or other object to be located within the array of capacitive touch electrodes. 
     Capacitive touch sensor electrodes may be interconnected with associated capacitive touch sensor processing circuits using interconnect lines that are formed on the same substrate as the capacitive touch sensor electrodes. For example, capacitive electrodes for a touch sensor and associated interconnect paths may be formed by screen printing silver ink patterns onto a touch sensor substrate. 
     Conventional screen printing techniques may, however, use interconnect patterns and layouts that result in undesirably bulky touch sensors. 
     It would therefore be desirable to be able to provide improved ways in which to form touch sensor arrays for touch sensors. 
     SUMMARY 
     Touch sensor arrays may be provided for touch pads in computers and other equipment. The touch sensor arrays may be formed from patterned conductive structures on substrates such as polymer substrates. A touch sensor array substrate may have a rectangular region that contains rows and columns of capacitive touch sensor electrodes, interconnects, and other conductive structures. One or more rectangular tab-shaped tails may protrude from an edge of the rectangular substrate region. 
     The conductive structures on the touch sensor array may be formed from patterned layers of ink. Interconnect line segments in different layer of ink may be connected in rectangular contact regions. A layer of insulator may be provided on the substrate. In some regions, the insulator layer may be formed directly on the surface of the substrate. Upper ink layer structures may be formed on the insulator layer in these regions. In other regions, the insulator layer may be interposed between lower ink layer structures and the upper ink layer structures. The insulator layer may be removed from a tip portion of the tail to allow the interconnect line segments from the upper ink layer structures to contact interconnect line segments from the lower ink layer structures. In the tip portion of the tail, none of the insulator layer is present, so the upper ink layer structures may contact the lower ink layer structures. Parts of the upper ink layer structures may also be formed directly on the substrate. Because the tip region of the tail is free of the insulator layer, none of the insulator layer is formed on the substrate in the portions of the tip region substrate that lie between adjacent interconnect lines. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative portable computer with a touch sensor in accordance with an embodiment of the present invention. 
         FIG. 2  is a perspective view of an illustrative touch pad having a touch sensor in accordance with an embodiment of the present invention. 
         FIG. 3  is a circuit diagram of an illustrative touch sensor showing how the touch sensor may include a touch sensor array and an associated touch sensor control circuit in accordance with an embodiment of the present invention. 
         FIG. 4  is a perspective view of an illustrative touch sensor array in accordance with an embodiment of the present invention. 
         FIG. 5  is a top view of a conventional touch sensor array. 
         FIG. 6  is a top view of a portion of a conventional touch sensor array showing how traces formed from different silver ink layers may be provided with enlarged circular ends that are connected to each other through a circular opening in an intervening layer of insulator. 
         FIG. 7  is a cross-sectional side view of portion of the conventional touch sensor array that is shown in  FIG. 6 . 
         FIG. 8  is a top view of an illustrative touch sensor array showing how the array may include a rectangular tail in accordance with an embodiment of the present invention. 
         FIG. 9  is a cross-sectional side view of a touch sensor array and associated circuitry in accordance with an embodiment of the present invention. 
         FIG. 10  is a top view of a portion of the touch sensor array of  FIG. 9  in the vicinity of a tail structure in accordance with an embodiment of the present invention. 
         FIG. 11  is a cross-sectional side view of the sensor array of  FIG. 10  in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices such as portable computers, touch pads, and other electronic equipment may be provided with touch sensors. 
     An illustrative electronic device such as a portable computer or other electronic equipment that has a touch pad is shown in  FIG. 1 . As shown in  FIG. 1 , device  10  may have a housing such as housing  12 . Housing  12  may be formed from a unibody construction in which some or all of housing  12  is formed form a unitary piece of material (e.g., metal, plastic, or fiber composite materials) or may be formed from multiple structures that have been mounted together using adhesive, fasteners, and other attachment mechanisms. For example, housing  12  may be formed from frame members and other internal supports to which external plates, housing sidewalls, bezel structures, and other structures are mounted. 
     Housing  12  may include display housing  12 A and base housing  12 B. Display  14  may be mounted in display housing  12 A. Components such as keyboard  16  and touch pad  18  may be mounted in base housing  12 B. Display housing  12 A and base housing  12 B may be connected using hinge structures. 
     During use of device  10 , a user may move one or more fingers or other external objects over the surface of touch pad  18 . Touch pad  18  may contain a touch sensor array that senses the locations of the user&#39;s finger(s). Using this type of arrangement, a user may provide touch input to control the operation of device  10 . 
     If desired, accessories such as keyboards and stand-alone touch pads may be provided with touch sensor arrays. Device  10  of  FIG. 2  has a housing (housing  12 ) with an exposed planar surface that forms a touch pad (stand-alone touch pad  18 ). Device  10  of  FIG. 2  may be wirelessly connected to external equipment such as host  20  using wireless link  22  or may be connected to host  20  using wired path  24 . 
     Other equipment may include touch sensors if desired. The examples of  FIGS. 1 and 2  are merely illustrative. 
     Touch pad sensors such as the sensors in touch pad  18  of  FIG. 1  and touch pad  18  of  FIG. 2  may be based on any suitable touch technology. For example, touch pads  18  may include resistive touch sensors, acoustic touch sensors, pressure-based touch sensors (e.g., touch sensors based on force sensors), or capacitive touch sensors (as examples). Capacitive touch sensors, which are sometimes described herein as an example, include arrays of capacitor electrodes for sensing changes in capacitance due to the presence of a user&#39;s fingers or other external objects at particular locations on the surface of the touch sensor. In a typical configuration, capacitor electrodes in a capacitive touch sensor are formed in an array pattern having rows and columns of sensor elements. Conductive lines may extend along the rows and columns of sensor elements to gather signals from the sensor elements. Interconnects may be used to route signals from the rows and columns to external circuitry. 
       FIG. 3  is a circuit diagram showing how touch pad  18  may include a communications path such as path  30  for routing signals from touch sensor array  26  to control circuitry  28 . Touch sensor array  26  may include an array of capacitive touch sensor electrodes or other touch sensor components. The capacitive touch sensor electrodes may be formed on a substrate. Path  30  may be formed from interconnect traces that are formed on the same substrate as the capacitive touch electrode and external cables such as flex circuit cables. Control circuitry  28  may include analog circuitry and digital circuitry. The analog circuitry may be used in measuring analog capacitance values from an array of capacitive electrodes. The digital circuitry may process the results of the analog capacitance measurements to extract position information from the sensor (i.e., to determine the positions of the user&#39;s fingers or other external objects on the surface of the touch sensor). 
     A perspective view of a touch sensor array that may be used in touch pad  18  is shown in  FIG. 4 . As shown in  FIG. 4 , touch sensor array  26  may include a substrate such as substrate  32 . Substrate  32  may be formed from a rigid material or a flexible material. Examples of rigid substrate materials include rigid printed circuit board materials such as fiberglass-filled epoxy, glass, ceramic, etc. Examples of flexible substrate materials include flexible polyimide sheets, flexible sheets of polyethylene terephthalate (PET), or other flexible polymer layers. 
     Substrate  32  may, in general, have any suitable shape (e.g., a shape with protruding portions, a shape with straight edges, a shape with curved edges, a shape with curved and straight edges, etc.). As shown in  FIG. 4 , for example, substrate  32  may have a main rectangular portion such as rectangular portion  38 . Substrate  32  may also have one or more tail portions such as tail portion  40 . Tail portion  40  may, for example, be a rectangular tab that protrudes from one of the edges of rectangular substrate portion  38 . 
     Conductive structures  34  are preferably arranged in rows and columns on substrate to form an array of capacitive electrodes. Multiple layers of conductive material may be used in forming conductive structures  34 , so that row structures and column structures may intersect without shorting (e.g., so that overpass or underpass structures may be formed). Conductive structures  34  may include pads, serpentine structures, vertical and horizontal lines, and other structures for forming an array of capacitive electrodes and for routing signals from the array of capacitive electrodes to the edge portions of substrate  32 . Interconnect lines in conductive structures  34  may run along the edges of substrate portion  38  and may extend onto tail  40  as shown schematically by dashed lines  36 . When assembled into a completed touch pad sensor, tail  40  may be inserted into a connector. In the connector, the interconnect traces on tail  40  may mate with corresponding connector contacts. If desired, other types of connection arrangements may be used to connect interconnects in tail  40  to external components. For example, pads formed from conductive adhesive (e.g., anisotropic conductive film or anisotropic paste) may be used to connect interconnects in tail  40  to corresponding contact pads and traces on a mating printed circuit board. 
       FIG. 5  is a top view of a conventional touch sensor array. As shown in  FIG. 5 , conventional touch sensor array  46  has substrate  62  onto which two layers of screen-printed silver ink structures  60  and insulating layers are formed. The pattern of silver ink structure  60  on substrate  62  forms an array of capacitive sensor electrodes and interconnect lines for connecting the capacitive sensors electrodes with external circuitry. 
     Substrate  62  has protrusions  50  and  52 . When sensor array  46  is mounted in a device, protrusions  50  and  52  typically wrap under the main portion of substrate  62 . As shown in  FIG. 5 , dome switch  48  is mounted on protrusion  50 . Protrusion  52  forms a yoke-shaped tail portion of substrate  62  onto which the interconnect structures in structures  62  travel to interconnect sensor  46  with external components. Opening  58  separates portion  54  of tail  52  from portion  56  of tail  52 . The yoke shape of tail  52  can help ensure that the interconnect lines that feed the tail are not overly crowded, but consumes a relatively large amount of space when tail  52  is wrapped under the main portion of substrate  62 . 
     When forming a desired pattern of conductive structure  60  on substrate  62 , it is sometimes necessary to interconnect the two layers of silver ink. A typical arrangement for forming a connection between upper and lower silver ink layers in conventional sensor array  46  is shown in  FIG. 6 . In the example of  FIG. 6 , a first conductive line (line  66 ) is being connected to a second conductive line (line  68 ) in circular contact region  64 . Line  66  may be formed in a lower layer of silver ink and line  68  may be formed in an upper layer of silver ink. A layer of insulator may be interposed between the upper and lower silver ink layers. Circular opening  70  may be formed in the layer of insulator to allow line  66  to connect to line  68 . In contact region  64 , lines  66  and  68  have enlarged circular shapes. 
     A cross-sectional side view of the conventional sensor array structures of  FIG. 6  taken along line  72  and viewed in direction  74  is shown in  FIG. 7 . As shown in  FIG. 7 , line  66  may be formed from a lower layer of silver ink on substrate  62 . Insulating layer  76  is formed on top of line  66  and abuts both the near and far sides of line  76 . Opening  70  is formed in insulating layer  76 . Line  68  may be formed from an upper layer of silver ink on top of insulating layer  76 . Opening  70  allows line  68  to extend downwards to contact line  66  in circular contact region  64 . Insulating layer  78  may cover line  68  and the other structures in  FIG. 7 . 
     Conventional sensor array ink conductors tend to occupy more space than desired, due to the size requirements of the enlarged circular portions of lines such as lines  66  and  68  of  FIGS. 6 and 7  and the alignment requirement imposed by circular opening  70 . This can cause conventional sensor arrays such as sensor array  46  of  FIG. 5  to be excessively large. 
     A sensor array of the type that may be used in devices such as device  10  of  FIG. 1  or device  10  of  FIG. 2  is shown in  FIG. 8 . As shown in  FIG. 8 , sensor array  26  may include conductive structures  34  on substrate  32 . Substrate  32  may be a PET substrate or may be formed from other suitable materials (e.g., flexible sheets of other polymers, glass, ceramic, rigid printed circuit board material, etc.). Conductive structures  34  may be formed from one or more layers of patterned conductive material such as one or more layer of conductive ink (e.g., silver ink). The conductive ink or other conductive material may be deposited using ink-jet printing, pad printing, shadow mask deposition, etching, lift-off techniques, or other suitable techniques. With one illustrative arrangement, silver ink or other conductive ink is deposited in a desired pattern on substrate  32  using screen printing. 
     Patterned conductive material  34  may form capacitive sensor electrodes, conductive lines (e.g., peripheral interconnect lines or paths in a grid of electrodes), and other conductive structures. The patterned conductive material may, for example, form capacitive electrodes in rows and columns across sensor array portion  38  of substrate  32 . Sensor array portion  38  may, for example, have a rectangular shape. Some of the patterned conductive material may extend into tail region  40 . Tail region  40  may have a base region such as region  112  and a tip region such as tip region  108 / 110 . Conductive interconnect lines  34  may extend through base region  112  into tip region  108 / 110 . 
       FIG. 9  is a cross-sectional side view of touch pad  18 . As shown in  FIG. 9 , touch pad  18  may include a touch sensor array such as touch sensor array  26  of  FIG. 8 . Touch sensor array  26  may be mounted under glass layer  80 . During operation of touch pad  18 , touch sensor array  26  may sense the location of a user&#39;s fingers or other external objects on the exposed surface of glass layer  80  (see, e.g., object  106  of  FIG. 9 ). 
     To block internal components in sensor  18  from view by a user, the inner surface of glass layer  80  may be coated with an opaque masking layer such as ink layer  82 . Ink layer  82  may be black, silver, gray, white, blue, green, red, or may have other suitable colors or patterns with multiple colors. 
     Adhesive layer  84  may be used to attach glass layer  80  (and opaque masking layer  82 ) to substrate  32  of sensor  26 . Underside portion  86  of sensor  26  may include conductive structures  34  ( FIG. 8 ). Adhesive layer  88  may be used to attach underlying structures in touch pad  18  to the lower surface of sensor  26 . For example, layers such as layers  90  and  92  may be attached to sensor  26  using one or more layers of adhesive. Layer  90  may be, for example, a layer of metal such as a layer of aluminum foil (e.g., to form a shielding ground plane). Layer  92  may be, for example, a printed circuit board on which components  94  may be mounted. Components  94  may include integrated circuits for monitoring capacitance signals in sensor array  26 . A connector such as connector  96  may receive the tip of substrate tail  40 . Contacts in connector  96  may make electrical contact with mating conductive lines  34 . 
     Flex circuit cable  104  or other communications path structure may be used to interconnect printed circuit board  92  and the circuitry that is connected to board  92  such as sensor  26  and components  94  to external boards. For example, cable  104  may be used to route signals to and from printed circuit board  98 . Additional components  100  and additional connectors such as connector  102  may be mounted on printed circuit board  98 . Cable  104  may extend between a connector on board  92  and connector  102  on board  98 . 
     Sensor array  26  may use multiple layers of material  34 . For example, multiple layers of silver ink (e.g., two or more layers) may be used to form sensor electrodes and interconnect lines on substrate  32 . An insulating layer such as a layer of polymer (e.g., acrylic) or other dielectric may be interposed between adjacent layers of silver ink. When multiple layers of patterned ink are used in this way, patterns of conductors may be formed that pass over and under one another without shorting. When it is desired to transfer signals between one level of patterned ink to another, portions of the dielectric layer may be removed. 
     To help minimize size, sensor array  26  and the conductive paths on sensor array  26  may be formed using structures that use space efficiently. In particular, interconnect lines may include inter-layer contacts with minimal width. The width of the interconnect lines in contact (overlap) regions in which layer-to-layer connections are formed may, for example, be less than 0.3 mm, less than 0.25 mm, or less than 0.2 mm (as examples). Interconnect lines may have substantially straight edges in the contact regions and in the portions of the interconnect lines immediately adjacent to the contact regions. This type of arrangement may allow interconnects in tail  40  and other portions of sensor array  26  to be formed using compact layouts that help minimize the size of sensor array  26  and touch pad  18 . 
       FIG. 10  is a top view of an illustrative portion of sensor array  26  in the vicinity of conductive material  34  (e.g., interconnect lines) that have been patterned to form at least one layer-to-layer connection. In the example of  FIG. 10 , the portion of the sensor array that is shown includes tail  40 . Other portions of sensor array  26  may use layer-to-layer connection structures and layouts of the type shown in  FIG. 10  if desired. The arrangement of  FIG. 10  is merely illustrative. 
     As shown in  FIG. 10 , tail  40  may have a plurality of parallel interconnect lines such as lines  118  and  124 . These lines may have longitudinal axes that run parallel to each other and run parallel to line  114 , which serves as the longitudinal axis of the central interconnect line in the portion of tail  40  shown in  FIG. 10 . Lines  118  and  124  may terminate at contacts that are covered with pads  132  of carbon or other suitable coating material to improve durability when forming contacts with conductive structures in a connector such as connector  96  of  FIG. 9 . During operation of sensor  26 , lines such as lines  118  and  124  may be used to route signals between sensor array  26  and external circuitry (see, e.g., circuits  94  and  100  of  FIG. 9 ). 
     Some interconnect lines in tail  40  such as line  118  of  FIG. 10  may be formed from a conductive structure in a single layer of silver ink (e.g., the lower of two layers of silver ink in an illustrative two-ink-layer configuration). Other lines in tail  40  such as lines  124  may be formed from multiple layers of ink. For example, lines  124  may include line segments  126  that are formed from an upper layer of ink (e.g., the top layer in the two layers of silver ink in a two-layer system) and segments  128  that are formed in a lower layer of ink (e.g., the bottommost layer in the two layers of silver ink in a two-layer system). Upper layer segments  126  and lower layer segments  128  may form electrical connections in contact regions  130 . 
     To minimize area, contact regions  130  may be rectangular and the edges of the lines in contact regions  130  (and in the portions of the lines adjacent to contact regions  130 ) may be straight and parallel. Using integrated inter-layer contact structures such as these, line segments in different layers can be efficiently joined. 
     The widths of lines  118  and  124  may, if desired, be adjusted as a function of position along their lengths. For example, the width of single-layer line  118  may be reduced from width D 2  (e.g., 0.2 mm) to width D 1  (e.g., 0.15 mm) using width-changing step  120  or a more gradual width transition structure. Similarly, the width of lines  124  may be varied. Each line  124  may, for example, have a width of D 2  (e.g., 0.2 mm) that increases to width D 3  (e.g., 0.25 mm) at width-changing step  136  and that decreases to width D 1  (e.g., 0.15 mm) at width-changing step  134 . The use of relatively narrow width D 2  may help prevent the line segments of width D 2  from shorting to each other. The wider width D 3  that is used in the vicinity of overlap regions  130  may help to form a satisfactory low-contact-resistance layer-to-layer electrical connection. The relative narrower width D 1  that is used at the tip of tail  40  may help prevent adjacent lines from shorting to each other and may help ensure that carbon pads  132  will completely cover all exposed edges of the interconnect lines in outermost tip region  108  of tail  40 . 
     In region  108 , the conductive lines may be covered only by carbon pads  132  and no overlapping insulator layers. In inner tip region  110  and in region  112 , coating insulating layer  140  (e.g., an acrylic layer or other dielectric layer) may cover the interconnect lines (and parts of carbon pads  132 ). Line  138 , which represents the interface between regions  108  and  110  may correspond to the edge of insulating coating  140 . Line  122  may correspond to the edge of the insulating layer that is sometimes used to separate and electrically isolate the upper and lower silver ink layers in sensor  26 . Line  122  (i.e., the edge of the inter-layer isolation layer) may run perpendicular to the interconnect lines from edge to edge across substantially the entire width WT ( FIG. 8 ) of tail  40  and may cover only base portion  112  of tail  140 , while leaving the substrate in the tip of tail  140  (i.e., in tip region  108 / 110 ) uncovered by the inter-layer isolation layer and free of any inter-layer isolation layer material between adjacent interconnects. 
       FIG. 11  is a cross-sectional side view of tail  40  of  FIG. 10  taken along line  114  and viewed in direction  116 . As shown in  FIG. 11 , line  124  may include a first segment such as segment  126  that is formed from line structures in the upper layer of silver ink and a second segment such as segment  128  that is formed from line structures in the lower layer of silver ink. Insulating layers such as inter-layer isolation layer  142  may be formed from one or more layers of acrylic or other dielectric materials. 
     In some portions of the sensor array such as illustrative portion  144  of  FIG. 11 , portions of insulating layer  142  such as portion  146  may be interposed between conductive structures  128  in the lower ink layer and conductive structures  126  in the upper ink layer. This prevents the upper and lower ink layer structures from forming undesired short circuit connections (e.g., to allow conductors in the upper and lower layers to pass over or under each other in the rows and columns of the sensor array when no electrical connection is desired). 
     In some regions, however, such as contact region  130 , it is desired to form good Ohmic contact between layer 126  and  128 . This may be accomplished by removing insulator  142  from portions  108  and  110  of tail  40 , so that insulating layer  142  only is present in region  112  and so that tip region  108 / 110  of tail  40  is free of any of layer  142 . Upper ink layer structure  126  may step down over edge  122  of insulating layer  142  at the boundary between regions  110  and  112 . In contact region  130 , line segment structures  126  overlap line segment structures  128  and electrically connect segments  126  and  128 . 
     In region  108 , the tips of segments  128  may be covered with pad  132  (e.g., a carbon pad or other conductive pad). Insulating coating layer  140  may be used to cover lines  118  and segments  128  and  126  of lines  124  in regions  110  and  112 . Error free alignment and connections between upper layer line segments such as segments  126  and lower layer line segments such as segments  128  may be facilitated in tail  40  by the complete removal of insulator  142  from the tip of the tail region. In particular, connections are facilitated by removing insulator  142  from all portions of substrate  32  that lie to the left of edge  122  in  FIG. 11  (i.e., by removing insulating layer  142  from rectangular regions  108  and  110 ). Edge  122  may run perpendicular to axis  114  of tail  40  (i.e., the dimension parallel to the longitudinal axis of each of interconnect lines  118  and  124  in tail  40 , as shown in  FIG. 10 ). 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

Metadata:
Filing Date: 20101015
Publication Date: 20190122
Grant Date: 20190122
Priority Date: 20101015
Inventors: OSBORN, JAY KEVIN
RICHARDS, PETER W.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F3/044", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0447", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0445", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0447", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0445", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 44872613