PATENT DOCUMENT

Publication Number: US-9532450-B2
Application Number: US-201414203161-A
Country: US
Kind Code: B2

Title: Lowering the sheet resistance of a conductive layer

Abstract:
An electronic device can include a substrate and a conductive layer. The conductive layer can be disposed over at least a portion of the substrate and a patterned conductive material can be disposed over at least a portion of the conductive layer. Alternatively, the patterned conductive layer can be disposed over at least a portion of a surface of the substrate and the conductive layer can be disposed over a portion of the surface of the substrate and in between the patterned conductive material. The conductive layer can be disposed over at least a portion of the patterned conductive material. The patterned conductive material can have a resistivity that is lower than a resistivity of the conductive layer.

Claims:
We claim: 
     
       1. A display stack comprising:
 a substrate comprising a display layer; 
 a first conductive layer positioned below the display layer; 
 a first conductive contact positioned below the substrate and along an edge of the first conductive layer; 
 a second conductive contact positioned above the substrate; and 
 a conductive material encapsulating at least a portion of the first conductive contact and the second conductive contact and encapsulating at least a portion of an intervening edge of the substrate extending between the first and second conductive contacts. 
 
     
     
       2. The display stack of  claim 1 , wherein the conductive material electrically connects the first conductive contact and the second conductive contact. 
     
     
       3. The display stack of  claim 1 , wherein the first conductive layer is disposed over a portion of the first conductive contact. 
     
     
       4. The display stack of  claim 1 , further comprising a second conductive layer positioned above the display layer and adjacent the second conductive contact, the second conductive layer electrically connected to the second conductive contact. 
     
     
       5. The display stack of  claim 4 , further comprising an electrical connector electrically connecting the second conductive layer to the second conductive contact. 
     
     
       6. The display stack of  claim 5 , wherein the conductive material electrically connects the first conductive layer and the second conductive layer via the first conductive contact and the second conductive contact, respectively. 
     
     
       7. The display stack of  claim 1 , wherein the conductive material is disposed over a portion of the substrate. 
     
     
       8. An electronic device comprising:
 a display stack comprising:
 a substrate comprising a liquid crystal display (LCD) layer; 
 a conductive layer positioned below the LCD layer; 
 a first conductive contact positioned below the substrate and along a side of the LCD layer; 
 a second conductive contact positioned above the substrate; and 
 a conductive material encapsulating at least a portion of the first conductive contact and the second conductive contact and encapsulating at least a portion of an edge of the LCD layer. 
 
 
     
     
       9. The electronic device of  claim 8 , further comprising:
 a patterned conductive material disposed over one of:
 at least a portion of the conductive layer, or 
 at least a portion of the substrate such that the conductive layer is disposed over the patterned conductive material. 
 
 
     
     
       10. The electronic device of  claim 9 , further comprising an electrical connector electrically connecting the conductive layer to the first conductive contact. 
     
     
       11. The electronic device of  claim 9 , further comprising an electrical connector electrically connecting the patterned conductive material disposed over at least a portion of the substrate to the first conductive contact. 
     
     
       12. The electronic device of  claim 9 , wherein the patterned conductive material includes a resistivity that is lower than a resistivity of the conductive layer. 
     
     
       13. The electronic device of  claim 9 , wherein the patterned conductive layer is disposed over at least a portion of a perimeter of the conductive layer. 
     
     
       14. The electronic device of  claim 9 , further comprising a layer disposed over at least a portion of the conductive layer and at least a portion of the patterned conductive material disposed over the conductive layer. 
     
     
       15. The electronic device of  claim 14 , further comprising a third conductive contact positioned below the substrate,
 wherein the third conductive contact is electrically connected to the layer disposed over at least the portion of the conductive layer and at least the portion of the patterned conductive material disposed over the conductive layer. 
 
     
     
       16. The electronic device of  claim 9 , wherein the patterned conductive material is fragmented. 
     
     
       17. The electronic device of  claim 16 , wherein the conductive layer is disposed around the fragmented patterned conductive material disposed over at least the portion of the substrate.

Description:
TECHNICAL FIELD 
     The present invention relates generally to electronic devices, and more specifically to electrical connections in electronic devices. 
     BACKGROUND 
     Electronic devices, such as smartphones and computers, include devices formed with one or more substrates or layers. For example, a display in a smartphone can include a display stack formed with multiple layers. The layers can include a cover glass, a polarizer, a conductive layer, a color filter, and a display layer. Conductive contacts, such as, for example, contact pads can be used to transmit electrical signals to and from various components on a layer or to a layer itself. 
       FIG. 1  illustrates an electrical connection between conductive contacts on two substrates. A conductive contact  100  is disposed over the front surface of a substrate  102  and another conductive contact  104  is disposed over a back surface of another substrate  106 , although in some situations the contacts may be disposed over the front and back of the same substrate. A flexible cable  108  is used to form an electrical connection between the conductive contacts  100 ,  104 . The flexible cable has a bend radius that limits how sharp the bend in the flexible cable  108  can be between the two conductive contacts  100 ,  104 . Due at least in part to its bend radius, the flexible cable can consume considerable area in an electronic device. The amount of area consumed by the flexible cable can be an issue when the size of the electronic device is small. 
     Additionally, the bend in the flexible cable can produce cracks in one or more conductive traces included in the flexible cable. The cracks can be created when the flexible cable is first bent or the cracks can develop over time. Either way, the cracks in the conductive traces can prevent electrical signals from being transmitted through the entire length of the flexible cable, which can render the electronic device inoperable. 
     In some embodiments, a conductive layer can be electrically connected to one of the conductive contacts (e.g.,  104 ) and a signal transmitted to the conductive layer using the conductive contact. The sheet resistance of the conductive layer, however, can cause the signal to be non-uniform across the surface of the conductive layer. This non-uniformity can adversely affect the performance of the electronic device. For example, if the conductive layer is connected to ground for electrostatic discharge (ESD) protection, the ESD protection may be ineffective due to the non-uniformity of the ground signal across the conductive layer. 
     SUMMARY 
     In one aspect, an electronic device can include a conductive layer disposed over at least a portion of a surface of a substrate. A patterned conductive material can be disposed over at least a portion of the conductive layer. The patterned conductive material can have a resistivity that is lower than a resistivity of the conductive layer. 
     In another aspect, an electronic device can include a patterned conductive material disposed over at least a portion of a surface of a substrate. A conductive layer can be disposed over at least a portion of the surface of the substrate and between the patterned conductive layer. The conductive layer may also be disposed over at least a portion of the patterned conductive material. The conductive layer can have a resistivity that is higher than a resistivity of the patterned conductive material. 
     In another aspect, an electronic device can include a conductive layer disposed over at least a portion of a surface of a substrate. A patterned conductive material can be disposed over at least a portion of the conductive layer. The patterned conductive material can have a resistivity that is lower than a resistivity of the conductive layer. A layer can be disposed over at least a portion of the conductive layer and at least a portion of the patterned conductive material. A conductive contact can be disposed over the surface of the substrate. A conductive material can electrically connect the conductive contact to the layer disposed over the conductive layer. 
     In another aspect, an electronic device can include a conductive layer disposed over at least a portion of a surface of a substrate. A patterned conductive material can be disposed over at least a portion of the conductive layer. The patterned conductive material can have a resistivity that is lower than a resistivity of the conductive layer. A layer can be disposed over at least a portion of the conductive layer and at least a portion of the patterned conductive material. An electrical connector can electrically connect the conductive layer to the layer disposed over the conductive layer. 
     In an additional aspect, a display stack may include a substrate, a first conductive contact positioned below the substrate and a first conductive layer positioned below the substrate. The first conductive layer may be electrically connected to the first conductive contact. The display stack may also include a second conductive contact positioned above the substrate, and a conductive material disposed over at least a portion of the first conductive contact and the second conductive contact. 
     In a further aspect, an electronic device may include a substrate, a conductive layer disposed over at least a portion of the substrate, and a patterned conductive material. The patterned conductive material may be disposed over one of: at least a portion of the conductive layer, or at least a portion of the substrate. Where the patterned conductive material is disposed over a portion of the substrate, the conductive layer is disposed over the patterned conductive material. The electronic device may also include a first conductive contact positioned below the substrate, a second conductive contact positioned above the substrate, and a conductive material disposed over at least a portion of the first conductive contact and the second conductive contact. 
     In another aspect, a method for forming an electrical connection in an electronic device may include determining if at least one mask is applied to at least one of: at least a portion of a substrate, or at least one layer of an electrical connection. The method may also include determining if an insulating material is initially applied to at least one of: at least the portion of the substrate, or at least one layer of the electrical connection. In the method, in response to determining the insulating material is applied, an insulating material may be formed over at least one of: at least the portion of the substrate, or at least one layer of the electrical connection. Alternatively, in response to determining the insulating material is not applied, at least one distinct layer of the electrical connection may be formed. The method of additionally include determining if the insulating material is subsequently applied to at least one of: at least the portion of the substrate, or the at least one distinct layer of the electrical connection. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments are better understood with reference to the following drawings. The elements of the drawings are not necessarily to scale relative to each other. Identical reference numerals have been used, where possible, to designate identical features that are common to the figures. 
         FIG. 1  illustrates an electrical connection between conductive contacts on two substrates in accordance with the prior art; 
         FIGS. 2A-2C  depict perspective views of examples of electronic devices in an embodiment; 
         FIG. 3  illustrates a simplified, schematic cross-section view of the display taken along line  3 - 3  in  FIG. 2B  in an embodiment; 
         FIG. 4  depicts a top view of the display layer shown in  FIG. 3  and one example of an electrical connection to the electrical contact in an embodiment; 
         FIG. 5  illustrates a cross-section view of the substrate and electrical connection taken along line  5 - 5  in  FIG. 4 ; 
         FIG. 6  depicts an example of a substrate with conductive contacts on different surfaces in an embodiment; 
         FIG. 7  illustrates a cross-section view of another example of electrical connections in an embodiment; 
         FIG. 8  depicts a top view of the electrical connections shown in  FIG. 7  in an embodiment; 
         FIG. 9  illustrates a top view of an example of conductive contacts on a substrate in an embodiment; 
         FIG. 10  depicts a cross-section view of an example of electrical connections taken along line  10 - 10  in  FIG. 9  in an embodiment; 
         FIG. 11  illustrates a cross-section view of another example of electrical connections taken along line  11 - 11  in  FIG. 9  in an embodiment; 
         FIG. 12  depicts a top view of an example of conductive contacts on a substrate in an embodiment; 
         FIG. 13  illustrates a cross-section view of an example of electrical connections taken along line  13 - 13  in  FIG. 12  in an embodiment; 
         FIG. 14  depicts a top view of a substrate and electrical connections in an embodiment; 
         FIG. 15  illustrates one example of patterned conductive material over a conductive layer in an embodiment; 
         FIG. 16  depicts another example of patterned conductive material over a conductive layer in an embodiment; 
         FIG. 17  illustrates another example of patterned conductive material over a conductive layer in an embodiment; 
         FIG. 18  depicts one example of a conductive layer with patterned conductive material in an embodiment; 
         FIG. 19  illustrates a cross-section view of one example of electrical connections to the conductive layer of  FIG. 18  in an embodiment; 
         FIG. 20  depicts a cross-section view of another example of electrical connections to the conductive layer of  FIG. 18  in an embodiment; 
         FIG. 21  illustrates one example of the substrate and the conductive layer shown in  FIG. 19  connected to another layer in an embodiment; 
         FIG. 22  is a flowchart of one example of a method for forming an electrical connection or patterned conductive material over a layer or a substrate in an embodiment; and 
         FIGS. 23-25  depict examples of a ground connection for the embodiment shown in  FIG. 21 . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments described herein may provide an electrical connection between conductive contacts disposed over two different surfaces of a single substrate or on two or more substrates. As one example, first and second conductive contacts may be located on opposite sides of a substrate and connected to one another, in full or in part, by a conductive material. A conductive material may be disposed over at least portions of the conductive contacts to electrically connect the conductive contacts. In some embodiments, the conductive material also overlies, contacts, or is otherwise adjacent to an intervening edge of the substrate between the two contacts. The conductive material may be formed from metal, a conductive polymer, a mesh or nanowire, a ceramic, an impregnated resin and the like. The conductive contacts can be used to transmit a signal or signals to components disposed over or in a substrate, to conductive layers disposed over different surfaces of a single substrate, or to conductive layers disposed over two or more substrates. 
     In another embodiment, a signal can be transmitted over the conductive layer using patterned conductive material disposed over the substrate and/or over the conductive layer. The patterned conductive material can be used to lower the sheet resistance of the conductive layer to improve signal transmission across the surface of a conductive layer. Additionally or alternatively, the patterned conductive material can be used to protect a touch-sensing circuit, element, or array of elements from noise generated by an electronic device that incorporates the touch-sensing technology. The patterned conductive material can act as a ground plane, shielding a touch-sensing circuit, element, or array of elements from parasitic capacitances that may arise when a metal housing of an electronic device incorporating the touch-sensing element(s) deforms. 
     In another embodiment, a layer can be connected to a reference voltage or signal to prevent or reduce noise or other signal processing issues. For example, a back polarizer in a display stack can be connected to a reference level, such as ground, and used, in part, to protect the display stack or electronic device from electrostatic discharge (ESD). Embodiments described herein provide various method and structures for connecting the layer to the reference voltage. 
     Directional terminology, such as “top”, “bottom”, “front”, “back”, “leading”, “trailing”, etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments described herein can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration only and is in no way limiting. When used in conjunction with a substrate, a layer, substrates, or layers in an electrical device, such as the layers in a display stack included in an electronic device, the directional terminology is intended to be construed broadly, and therefore should not be interpreted to preclude the presence of one or more intervening layers or other intervening device features or elements. Thus, a given substrate or layer that is described herein as being formed on, formed over, disposed over, or disposed over another layer may be separated from the latter layer by one or more additional layers. 
     Further, the term “electronic device” is to be understood as any type of electronic device, including, but not limited to, a cellular telephone or smart telephone, a tablet computer, a computing device, an integrated circuit, and a printed circuit board or boards. 
     Referring now to  FIGS. 2A-2C , there are shown front perspective views of examples of electronic devices. As shown in  FIG. 2A , the electronic device  200  can be a laptop or netbook computer that includes a display  202  and a touch device  204 , shown in the illustrated embodiment as a trackpad. An enclosure  206  can form an outer surface or partial outer surface and protective case for the internal components of the electronic device  200 , and may at least partially surround the display  202  and the trackpad  204 . The enclosure  206  can be formed of one or more components operably connected together, such as a front piece and a back piece. 
     The display  202  is configured to display a visual output for the electronic device  200 . The display can be implemented with any suitable display, including, but not limited to, a liquid crystal display (LCD), an organic light-emitting display (OLED), or organic electro-luminescence (OEL) display. 
     The trackpad  204  can be used to interact with one or more viewable objects on the display  202 . For example, the trackpad  204  can be used to move a cursor or to select a file or program (e.g., represented by an icon) shown on the display. The trackpad  204  can use capacitive sensing to detect an object, such as a finger or a conductive stylus, near or on the surface of the trackpad  204 . The trackpad  204  can include a capacitive sensing system that detects touch through capacitive changes at capacitive sensors. Additionally or alternatively, the same or another capacitive sensing system can be used to detect an amount of force applied to the trackpad using capacitive changes. 
       FIG. 2B  is a front perspective view of another electronic device, a smart telephone  209  that includes an enclosure  210  surrounding a display  212  and one or more buttons  214  or input devices. The enclosure  210  can be similar to the enclosure described in conjunction with  FIG. 2A , but may vary in form factor and function. 
     The display  212  can be implemented with any suitable display, including, but not limited to, a multi-touch capacitive sensing touchscreen (i.e., a touch device) that uses liquid crystal display (LCD) technology, organic light-emitting display (OLED) technology, or organic electro luminescence (OEL) technology. A capacitive sensing touchscreen device can detect a touch or force using capacitive changes at capacitive sensors. 
     The button  214  can take the form of a home button, which may be a mechanical button, a soft button (e.g., a button that does not physically move but still accepts inputs), an icon or image on a display, and so on. Further, in some embodiments, the button  214  can be integrated as part of a cover glass of the electronic device. 
     Referring now to  FIG. 2C , there is shown a front perspective view of another electronic device. In the illustrated embodiment, the electronic device  216  is a tablet computer that can include a display  218 , an enclosure  220 , and one or more buttons  222  or input devices. The enclosure, display, and the one or more buttons  222  can be similar to the enclosure, display, and button described in conjunction with  FIG. 2B , but may vary in form factor and function. 
     The electronic device  216  can also include one or more receiving ports  224 . A receiving port  224  can receive one or more plugs or connectors, including, but not limited to, a universal serial bus cable, a tip ring sleeve connector, or the like. 
       FIG. 3  illustrates a cross-section view of the display taken along line  3 - 3  in  FIG. 2B  in an embodiment. The layers of the display stack  300  can include the layers that constitute the display  202 . For example, a top layer in the display stack  300  can be a cover glass (not shown) that is disposed over a front polarizer  304 . The front polarizer  304  is disposed over a front transparent conductive layer  306 , such as, for example, an ITO layer. The front transparent conductive layer  306  may, for example, provide electrostatic protection to prevent electrical discharge into the display. 
     The front transparent conductive layer  306  is disposed over a color filter layer  308  that is disposed over a display layer  310 . The display layer  310  may take a variety of forms, including a LCD, an LED display, and an OLED display. In many embodiments, the display layer may be formed from glass or have a glass substrate. 
     A back transparent conductive layer  312  is below the display layer  310 . The back transparent conductive layer  312  is disposed over a back polarizer  314 . The back transparent conductive layer  312  may serve to prevent noise from entering the system through the display stack and thus may function as an isolation plane. In alternative embodiments, one or both of the conductive layers may have other functions and/or other layers, elements, and the like may be part of the display stack  300 . 
     Since certain layers, elements or the like located on one or both sides of the display layer  310  may require an electrical signal (or the same electrical signal), it may be useful to place electrical contacts in close proximity to one another but on opposing sides of a substrate. In order to do so, front and back conductive contacts  316 ,  318  may be provided. 
     A front conductive contact  316  is disposed over a front surface of the display layer  310  and a back conductive contact  318  is disposed over an opposing back surface of the display layer  310 . The conductive contacts  316 ,  318  can be implemented with any suitable conductive material and formation, including, but not limited to, contact pads, flexible cable connectors, and conductive traces. 
     An electrical connector  320  may electrically connect the front transparent conductive layer  306  to the front conductive contact  316 . The back transparent conductive layer  312  may be electrically connected to the back conductive contact  318  in the illustrated embodiment using any given type of electrical connection. For example, the conductive layer  312  may be disposed over a portion of the back conductive contact  318  or an electrical connector (not shown) similar to the electrical connector  320  can connect the back transparent conductive layer to the back conductive contact. 
     Embodiments described herein may provide structures and methods for electrically connecting the back conductive contact  318  to the front conductive contact  316 , thereby allowing a signal or signals to be transmitted to or from the back conductive contact  318  using the front conductive contact  316 . In the illustrated embodiment, a signal or signals transmitted to the front conductive contact  316  can be transmitted to the front and back transparent conductive layers  306 ,  312  because the front conductive layer  306  is electrically connected to the front conductive contact  316  using electrical connector  320  and the back conductive contact  318  is electrically connected to the front conductive contact  316  using the techniques and methods described in more detail herein. It should be appreciated that the front and back conductive contacts  316 ,  318  may likewise provide electrical connections to additional layers or elements of the electronic device, or may provide such connections instead of providing connections to either of the conductive layers  306 ,  312 . 
     Those skilled in the art will recognize that other components or devices can be disposed over the display layer  310 . By way of example only, one or more integrated circuits (not shown) can be disposed over the display layer  310 . In some embodiments, the other components, including the conductive contacts, can be disposed in an area on the display layer  310  that extends into a region that is not visible by a user viewing the display of the electronic device. For example, when the electronic device is a smartphone or a tablet computing device, the other components and the conductive contacts are disposed over the display layer in an area that is covered by a black mask. 
     The front and back polarizers  304 ,  314  can be implemented in any suitable form and can include polarizers that are known and used in the art. Additionally, the color filter layer  308  can be implemented in any suitable form and can include a color filter layer that is known and used in the art. 
     Referring now to  FIG. 4 , there is shown a top view of the display layer  310  shown in  FIG. 3  and one example of an electrical connection to the front conductive contact  316  in an embodiment. Display layer  310  includes the front conductive contact  316 , a flexible cable connector  400 , and one or more integrated circuits  402 . A conductive material  404  is disposed over at least a portion of the front conductive contact  316 . The conductive material  404  can be implemented with any suitable conductive material or combination of materials, including, but not limited to, metal, silver nanowire, and conductive nanoparticles. 
       FIG. 5  illustrates a cross-section view of the display layer  310  and the electrical connection taken along line  5 - 5  in  FIG. 4 . The front polarizer  304  and the back polarizer  314  are not shown for simplicity. The conductive material  404  is disposed over at least a portion of the front surface  500  of the front conductive contact  316  and the back surface  502  of the back conductive contact  318 . The conductive material  404  can also be disposed over the surfaces  504  between the front and back surfaces  500 ,  502  of the front and back conductive contacts  316 ,  318 . 
     The surfaces of the conductive contacts in which the conductive material is disposed over are called contact surfaces. When the conductive material  404  is disposed over the front surface  500  of the front conductive contact  316  and the back surface  502  of the back conductive contact  318 , an electrical connection is formed. Some of the contact surfaces (i.e.,  500 ,  502 ) are oriented in opposite directions and the other contact surfaces are oriented in the same direction. In other embodiments, all or some of the contact surfaces can be oriented in the same directions or in different (opposite and non-opposite) directions.  FIG. 6  depicts an example of a substrate  600  with two conductive contacts  602 ,  604  on different surfaces. The conductive material  606  is disposed over multiple contact surfaces with all of the contact surfaces of the conductive contacts oriented in different directions. 
     Returning to  FIG. 5 , since the back transparent conductive layer  312  is electrically connected to the back conductive contact  318 , the back transparent conductive layer  312  is also electrically connected to the front conductive contact  316  through the conductive material  404 . A signal can be transmitted to or from the back transparent conductive layer  312  using the front conductive contact  316 , the conductive material  404 , and the back conductive contact  318 . For example, an unused existing electrical connection to front conductive contact  316  can be used to transmit a signal to the back transparent conductive layer  312  using conductive material  404  and back conductive contact  318 . Alternatively, a new electrical connection to the front conductive contact  316  can be added to the device and used to transmit a signal to or from the back transparent conductive layer  312  using conductive material  404  and back conductive contact  318 . 
     The conductive material  404  can be configured or shaped into any desired shape or thickness. For example, the conductive material  404  can be formed at a thickness or a shape that results in the conductive material consuming less area in an electronic device compared to a conventional flexible cable connection (see e.g.,  108  in  FIG. 1 ). Flexible cables may come in different thicknesses and widths, but flexible cables are substantially fixed in a shape and limited in part by a bend radius when connected to the conductive contacts. 
     Although the embodiment described in conjunction with  FIGS. 3-6  describes a display layer and a back transparent conductive layer, other embodiments are not limited to this construction. Any type of substrate, such as glass, plastic, printed circuit board, or flexible cable, can be used in place of the display layer and the back transparent conductive layer. Various embodiments can include an electrical connection between two conductive contacts on a single substrate or an electrical connection between two conductive contacts on different substrates. The contact surfaces of the conductive contacts can be oriented in different directions or in the same direction. The different directions can assume any difference in direction. By way of example only, the different directions can be opposite (180 degrees), at an acute angle with respect to each other, or at an obtuse or reflex angle with respect to each other. 
     Referring now to  FIG. 7 , there is shown a cross-section view of another example of electrical connections in an embodiment.  FIG. 8  depicts a top view of the electrical connections shown in  FIG. 7 . The conductive material  404  is disposed over at least a portion of the front conductive contact  316  and the back conductive contact  318  and, optionally, the surfaces between the conductive contacts. A first flexible cable connector  700  ( FIG. 7 ) is disposed over the front surface of a substrate  702  and a second flexible cable  704  is connected to the first cable connector  700 . The substrate  702  can be made of any suitable material or combination of materials including, but not limited to, glass, plastic, and flexible cable. The flexible cable  704  can be implemented with any suitable flexible cable, including, but not limited to, ribbon cable, flexible flat cable, flat panel cable, and flexible printed circuit. In other embodiments, the flexible cable  704  can be connected to the front conductive contact  316 . 
     Referring now to  FIG. 9 , there is shown a top view of an example of conductive contacts on a substrate in an embodiment. The substrate  900  can be made of any suitable material or combination of materials including, but not limited to, glass, plastic, and flexible cable. Conductive contacts  902 ,  904 ,  906 ,  908  are disposed over the front surface  910  of the substrate  900 . 
       FIG. 10  depicts a cross-section view of an example of electrical connections along line  10 - 10  for the embodiment shown in  FIG. 9 . Conductive material  1000  electrically connects the conductive contact  902  on the front surface  910  of the substrate  900  to a conductive contact  1002  on a back surface  1004  of the substrate  900 . Insulating material  1006  surrounds the conductive material  1000  to electrically isolate the electrical connection between the front and back conductive contacts  902 ,  1002 . 
     Conductive material  1008  electrically connects the conductive contact  904  on the front surface  910  of the substrate  900  to a conductive contact  1010  on the back surface  1004  of the substrate  900 . Insulating material  1012  surrounds the conductive material  1008  to electrically isolate the electrical connection between the front and back conductive contacts  904 ,  1010 . 
     Conductive material  1014  electrically connects the conductive contact  906  on the front surface  910  of the substrate  900  to a conductive contact  1016  on the back surface  1004  of the substrate  900 . Insulating material  1018  surrounds the conductive material  1014  to electrically isolate the electrical connection between the front and back conductive contacts  906 ,  1016 . 
     Conductive material  1020  electrically connects the conductive contact  908  on the front surface  910  of the substrate  900  to a conductive contact  1022  on the back surface  1004  of the substrate  900 . Insulating material  1024  surrounds the conductive material  1020  to electrically isolate the electrical connection between the front and back conductive contacts  908 ,  1022 . Outer insulating material  1024  is optional and is not included in some embodiments. For example, a device can omit the outer insulating material  1024  when the electrical connection between front and back conductive contacts  908 ,  1022  is connected to ground for electrostatic discharge (ESD) protection. 
     In the illustrated embodiment, the conductive material  1000 ,  1008 ,  1014 ,  1020  extends partially over the conductive contacts. In other embodiments, the conductive material can extend completely over the conductive contacts. Additionally, a different conductive material can be used to form each electrical connection or one or more electrical connections. For example, the conductive material  1014  can by of a different type than the other conductive materials  1000 ,  1008 , and  1020 . A different insulating material can also be used to isolate one or more electrical connections. 
     The electrical connections formed in the embodiment shown in  FIG. 10  can also be appropriate when only one contact is near an edge of the substrate and the other conductive contacts are positioned closer and closer to the middle of the substrate  900 . By way of example only, conductive contact  1002  (or conductive contacts  902 ,  1002 ) can be near an edge of the substrate  900  and the other conductive contacts  1010 ,  1016 ,  1022  (or  904 ,  906 ,  908 ) can be positioned closer and closer to the middle of the substrate  900 . 
       FIG. 11  illustrates a cross-section view of another example of electrical connections along line  11 - 11  for the embodiment shown in  FIG. 9 . Only conductive contacts  902 ,  904 , and  906  are shown in  FIG. 11  for simplicity. Conductive material  1000  electrically connects the conductive contact  902  on the front surface  910  of the substrate  900  to the conductive contact  1002  on the back surface  1004  of the substrate  900 . Insulating material  1006  surrounds the conductive material  1000  to electrically isolate the electrical connection between the front and back conductive contacts  902 ,  1002 . 
     Conductive material  1100  electrically connects the conductive contact  904  on the front surface  910  of the substrate  900  to a conductive contact  1102  on a back surface  1104  of another substrate  1106 . The substrate  1106  is disposed below the substrate  900 . Insulating material  1108  surrounds the conductive material  1100  to electrically isolate the electrical connection between the front and back conductive contacts  904 ,  1102 . 
     Conductive material  1110  electrically connects the conductive contact  906  on the front surface  910  of the substrate  900  to a conductive contact  1112  on a back surface  1114  of a substrate  1116 . The substrate  1116  is disposed below the substrate  1106 . Insulating material  1118  surrounds the conductive material  1110  to electrically isolate the electrical connection between the front and back conductive contacts  906 ,  1112 . 
     The conductive contact  908  (not shown) can be electrically connected to a conductive contact on the back surface  1114  of the substrate  1116 , or to a conductive contact on another substrate (not shown) that is disposed below the substrate  1116 . The electrical connections formed in the embodiment shown in  FIG. 11  can also be appropriate when one or more conductive contacts are positioned differently over a substrate. As discussed, the conductive contact  908  can be electrically connected to a conductive contact positioned closer to the middle of the substrate  1116  or to a conductive contact positioned near an edge on a separate substrate disposed below the substrate  1116 . 
     Referring now to  FIG. 12 , there is shown a top view of an example of conductive contacts on a substrate in an embodiment. The substrate  1200  can be made of any suitable material or combination of materials including, but not limited to, glass, plastic, and flexible cable. Conductive contacts  1202 ,  1204 ,  1206 ,  1208  are disposed over the front surface  1210  of the substrate  1200 . A flexible cable  1212  is connected to the conductive contact  1206 . The conductive contact  1206  can be implemented, for example, as a cable connector or a conductive contact pad. 
       FIG. 13  depicts a cross-section view of an example of electrical connections along line  13 - 13  for the embodiment shown in  FIG. 12 . Conductive material  1300  electrically connects the conductive contact  1202  on the front surface  1210  of the substrate  1200  to a conductive contact  1302  on a back surface  1304  of the substrate  1200 . Insulating material  1306  surrounds the conductive material  1300  to electrically isolate the electrical connection between the front and back conductive contacts  1202 ,  1302 . 
     Conductive material  1308  electrically connects the conductive contact  1204  on the front surface  1210  of the substrate  1200  to a conductive contact  1310  on the back surface  1304  of the substrate  1200 . Insulating material  1312  surrounds the conductive material  1308  to electrically isolate the electrical connection between the front and back conductive contacts  1204 ,  1310 . Insulating material  1312  also electrically isolates the electrical connection between the flexible cable  1212  and the conductive contact  1206 . 
     Conductive material  1314  electrically connects the conductive contact  1208  on the front surface  1210  of the substrate  1200  to a conductive contact  1316  on the back surface  1304  of the substrate  1200 . Insulating material  1318  surrounds the conductive material  1314  to electrically isolate the electrical connection between the front and back conductive contacts  1208 ,  1316 . Outer insulating material  1318  is optional and is not included in some embodiments. 
       FIG. 14  illustrates a top view of a substrate and electrical connections in an embodiment. The substrate  1400  can be fabricated in any shape or design. In the illustrated embodiment, the substrate  1400  has trenches  1402 ,  1404 ,  1406 . The trenches produce substrate fingers or protrusions, and conductive contacts  1408 ,  1410 ,  1412 ,  1414  are disposed over the substrate fingers. Conductive material  1416 ,  1418 ,  1420 ,  1422  is disposed over at least a portion of a respective conductive contact. 
     Those skilled in the art will recognize that a substrate can be fabricated in any given shape. Shaping the substrate can result in an easier fabrication process for the conductive contacts or electrical connections. By way of example only, if the substrate fingers are dipped in a conductive material, the substrate fingers can reduce the likelihood that conductive material will be formed on the non-finger portion of the substrate. 
     Additionally, shaping the substrate can allow for different conductive materials to be used to form one or more electrical connections. The conductive contacts  1408 ,  1410 ,  1412 ,  1414  can be electrically connected to conductive contacts on multiple substrates or on a single substrate. 
     In some embodiments, a conductive layer, such as, for example, the back transparent conductive layer  312  shown in  FIGS. 3 and 5 , can be implemented with a material, or combination of materials, that has a higher than desired impedance. For example, when the back transparent conductive layer  312  is formed with ITO, the impedance across the surface of the back transparent conductive layer  312  can be an issue when biasing the back transparent conductive layer  312 . The resistance to the center of the layer  312  generally is higher than the resistance at an edge of the back transparent conductive layer  312 , which can result in signal non-uniformity across the surface of the layer  312 . 
       FIG. 15  depicts one example of patterned conductive material over a conductive layer in an embodiment. The patterned conductive material can be used to improve signal transmission across the surface of a conductive layer in certain embodiments. Additionally or alternatively, the patterned conductive material can be used to protect a touch-sensing circuit, element, or array of elements from noise generated by an electronic device that incorporates the touch-sensing technology. One example of a touch-sensing technology is capacitive sensing. The capacitive sensing can be used, for example, to detect one or more touches on a surface of an electronic device, or to detect a force or amount of force applied to a flexible surface in an electronic device. 
     The patterned conductive material can act as a ground plane, shielding a touch-sensing circuit, element, or array of elements from parasitic capacitances that may arise when a metal housing of an electronic device incorporating the touch-sensing element(s) deforms. The deformation may change a distance between the metal housing and the touch-sensing element(s), which, in turn, may create a parasitic capacitance at the element(s). The patterned conductive material can shield the touch-sensing technology from such parasitic capacitances. 
     Conductive material  1501  is patterned into conductive borders  1500 ,  1502 ,  1504 ,  1506  that are disposed over a surface  1508  of the conductive layer  1510 . The conductive layer  1510  can be formed with any opaque or transparent conductive material or combination of materials. The patterned conductive material can be any type of opaque or transparent conductive material, including, but not limited to, a metal such as silver, or nanoparticles. The patterned conductive material can have a lower resistivity than the resistivity of the conductive layer, and the patterned conductive material may be used to lower the sheet resistance of the conductive layer. 
     The conductive borders  1500 ,  1502 ,  1504 ,  1506  are disposed around the perimeter edges of the conductive layer  1510  in the illustrated embodiment. Other embodiments can include only one conductive border or two or more conductive borders. A conductive border or borders can be formed prior to forming the conductive layer  1510 . Alternatively, a conductive border or borders can be formed after the formation of the conductive layer  1510 . 
     The conductive borders  1500 ,  1502 ,  1504 ,  1506  cooperate to form a conductive frame around the perimeter edges of the conductive layer  1510  in the illustrated embodiment. The conductive frame transmits a signal around the perimeter edges to improve signal uniformity across the surface of the conductive layer  1510 . By way of example only, the conductive layer  1510  can be the back transparent conductive layer  312  shown in  FIGS. 3 and 5 . As described earlier, the patterned conductive material, depicted as conductive borders, can at least be used to lower the sheet resistance of the back transparent conductive layer  312 . 
     Referring now to  FIG. 16 , there is shown another example of patterned conductive material over a conductive layer in an embodiment. The conductive material  1601  is patterned into corner sections  1600 ,  1602 . The corner sections  1600 ,  1602  are disposed over a surface  1604  of the conductive layer  1606 . Each corner section  1600 ,  1602  extends partially along two perimeter edges of the conductive layer  1606 . The sides of the corner sections  1600 ,  1602  can have the same dimensions (length, width, and thickness), or one or more sides can have different dimension (length, width, and/or thickness) from another side. Additionally or alternatively, the corner sections  1600 ,  1602  can be made of the same material or combination of materials, or one corner section can be made of a different material(s) than the other corner section. Likewise, one or more sides can be made of a different material(s) than another side. 
       FIG. 17  illustrates another example of patterned conductive material over a conductive layer in an embodiment. Conductive material  1701  is patterned into conductive segments  1700 ,  1702 . In the illustrated embodiment, some of the conductive segments  1700  have a first dimension while other conductive segments  1702  have a different second dimension. The conductive segments are fragmented in that each segment is not part of one continuous segment over the conductive layer  1706 . 
     Embodiments can form the patterned conductive material at any location over a conductive layer. The patterned conductive material can be patterned into any given shape, width, length, or thickness. The shapes can be continuous or fragmented. When fragmented, each conductive segment can be made of the same conductive material(s) or one or more segments can be made of a different conductive material or materials. 
     The patterned conductive material can be formed over a layer using any suitable fabrication method. By way of example only, the patterned conductive material can be deposited over a surface of a layer. The patterned conductive material can be deposited using, for example, photolithography, screen printing, or inkjet printing. A mask can be used to mask off areas where the patterned conductive material is not to be formed. The patterned conductive material can be used with one or more electrical connections formed between two conductive contacts using a conductive material (e.g., see  FIGS. 3, 5, 10, and 11 ). 
     Referring now to  FIG. 18 , there is shown one example of a conductive layer with patterned conductive material in an embodiment. Conductive material  1801  is patterned into conductive segments  1800 ,  1802 ,  1804 ,  1806 . The segments are disposed over a surface  1808  of a conductive layer  1810 .  FIG. 19  illustrates a cross-section view of one example of electrical connections to the conductive layer  1810  in an embodiment. A substrate  1900  is disposed over the conductive layer  1810 . The substrate  1900  can be any suitable type of substrate, including, but not limited to, glass. Two conductive contacts  1902 ,  1904  are disposed over a first surface of the substrate  1900  and two conductive contacts  1906 ,  1908  are disposed over a second surface of the substrate  1900 . In the illustrated embodiment, the second surface of the substrate opposes the first surface of the substrate. 
     Conductive material  1910  electrically connects the conductive contact  1902  to the conductive contact  1906 . Likewise, conductive material  1912  electrically connects the conductive contact  1904  to the conductive contact  1908 . An electrical connector  1914  electrically connects the conductive contact  1906  to the conductive layer  1810 , and an electrical connector  1916  electrically connects the conductive contact  1908  to the conductive layer  1810 . In an alternate embodiment, one or more electrical connectors can connect to the patterned conductive material (e.g.,  1800 ,  1804 ). 
       FIG. 20  depicts a cross-section view of another example of electrical connections to a conductive layer in an embodiment. Patterned conductive material (e.g.,  1800 ,  1804 ) is disposed over a surface of a substrate  1900 . The substrate  1900  can be any suitable type of substrate, including, but not limited to, glass. 
     A conductive layer  2000  is disposed over the surface of the substrate  1900  and between and/or around the patterned conductive material (e.g.,  1800 ,  1804 ). The conductive layer  2000  can also be disposed over some or all of the patterned conductive material (e.g.,  1800 ,  1804 ). The conductive layer  2000  and the patterned conductive material (e.g.,  1800 ,  1804 ) can be made of any suitable conductive material or combination of materials. 
     Two conductive contacts  1902 ,  1904  are disposed over a first surface of the substrate  1900  and two conductive contacts  1906 ,  1908  are disposed over a second surface of the substrate  1900 . In the illustrated embodiment, the second surface of the substrate opposes the first surface of the substrate. 
     Conductive material  1910  electrically connects the conductive contact  1902  to the conductive contact  1906 . Likewise, conductive material  1912  electrically connects the conductive contact  1904  to the conductive contact  1908 . An electrical connector  1914  electrically connects the conductive contact  1906  to the conductive layer  2000  and/or to the patterned conductive material (e.g.,  1800 ). An electrical connector  1916  electrically connects the conductive contact  1908  to the conductive layer  2000  and/or to the patterned conductive material (e.g.,  1804 ). 
     Some embodiments can use multiple electrical connections to bias the conductive layer and/or the patterned conductive material. Additionally or alternatively, one electrical connection can be used to transmit a signal to the conductive layer, and the signal can be transmitted across the conductive layer using the conductive properties of the conductive layer. With a fragmented patterned conductive material, the fragments can effectively be connected in series when using the conductive properties of the conductive layer to transmit a signal across the conductive layer. 
     Referring now to  FIG. 21 , there is shown one example of the substrate  1900  and the conductive layer  1810  shown in  FIG. 19  connected to another layer in an embodiment. An adhesive layer  2100  can be used to connect layer  2102  to the conductive layer  1810  and the patterned conductive material  1800 ,  1804 . By way of example only, the layer  2102  can be the back polarizer  314  in  FIG. 3 . The adhesive layer  2100  can be formed in between and/or around the patterned conductive material  1800 ,  1804 . The adhesive layer  2100  can also extend over some or all of the patterned conductive material  1800 ,  1804 . 
     The thickness of a stack of layers can be a factor in some embodiments. By way of example only, it can be desirable to minimize the thickness of the display stack shown in  FIG. 3  since the display stack can be included in a handheld portable device (e.g., a smart telephone). In these embodiments, the thickness of the patterned conductive material  1800 ,  1804  can be determined or limited by the thickness of the adhesive layer  2100 . For example, the thickness of the patterned conductive layer can be equal to, or less than a certain percentage of the adhesive layer  2100 . The maximum thickness of the patterned conductive material can be, for example, ten percent of the adhesive layer. 
     Additionally or alternatively, when the area that includes the patterned conductive material  1800 ,  1804  is limited, the patterned conductive material can be formed to be thicker to maintain a given amount of resistivity. In these embodiments, the adhesive layer  2100  may need to have sufficient stickiness or viscoelastic properties to effectively bond the layer  2102  to the conductive layer  1810  and the patterned conductive material  1800 ,  1804 . 
       FIG. 22  is a flowchart of one example of a method for forming an electrical connection or patterned conductive material over a layer or a substrate in an embodiment. Initially, a determination is made at block  2200  as to whether one or more masks is needed prior to forming an electrical connection or connections between conductive contacts, prior to forming patterned conductive material over a substrate or over a layer, or prior to forming insulating material over one or more conductive contacts or patterned conductive material. The mask(s) can be used to mask off previously formed components on, over, or in a substrate, or areas of a surface or surfaces where an electrical connection, patterned conductive material, or insulating material is not to be formed. 
     If one or more masks are needed, the method passes to block  2202  where the mask or masks are formed over the surface or surfaces of one or more substrates and/or layers. The mask can be formed over the substrate(s) or layer(s) using any suitable fabrication method. The mask can include masks that are known and used in the art. 
     Next, as shown in block  2204 , a determination is made as to whether insulating material is to be formed on or over conductive material, a substrate, and/or a layer. If insulating material is not to be formed, the process continues at block  2206  where one or more electrical connections and/or patterned conductive materials are formed. The electrical connection(s) or patterned conductive material can be formed, for example, by dipping the substrate or layer in a conductive material. Alternatively, the patterned conductive material or electrical connection(s) can be formed by depositing conductive material on a surface or on a conductive contact. Examples of conductive materials include, but are not limited to, metal, organic materials, nanoparticles, or combinations thereof. By way of example only, the electrical connection(s) can be deposited using a chemical vapor deposition process or a physical vapor deposition process, such as sputtering. The patterned conductive material can be formed using any suitable fabrication processing, including, but not limited to, a screen printing process, photolithography, or an inkjet printing process. 
     In some embodiments, the conductive material used to form an electrical connection or the patterned conductive material may need to be processed (e.g., cured) at a temperature that previously formed components or attached layers can withstand. For example, the curing process, as well as other processing steps, for the conductive material  404  or the patterned conductive material  1501 ,  1601 ,  1701  can be performed at a temperature that one or more layers, such as, for example, the substrate  310 , can withstand. 
     If necessary, the mask or masks are removed (block  2208 ). For example, if one or more masks were formed at block  2202 , the mask(s) can be removed. In some embodiments, however, the same mask or masks can be used for multiple processing procedures. 
     Returning to block  2204 , if insulating material is to be formed, the process continues at block  2210  where the insulating material is formed over the electrical connection and/or the patterned conductive material using any suitable method. By way of example only, the insulating material can be deposited over the conductive material that forms the electrical connection or the patterned conductive material. 
     If necessary, the mask or masks are removed (block  2212 ). For example, if one or more masks were formed at block  2202 , the mask(s) can be removed. In some embodiments, however, the same mask or masks can be used for multiple processing procedures. 
     As described earlier, electrical connections can be formed between different conductive contacts on a single substrate, between different conductive contacts on multiple substrates, or a different type of electrical connection can be formed, such as, for example, a connection using flexible cable. The patterned conductive material can be disposed over a substrate and/or a conductive layer. 
     In some embodiments, a layer is connected to a reference voltage or signal to prevent or reduce noise or other signal processing issues. For example, the back polarizer  314  in the display stack shown in  FIG. 3  can be connected to a reference level, such as ground.  FIG. 23  depicts one example of a ground connection for the embodiment shown in  FIG. 21 . A conductive adhesive layer  2300  can be used to connect the layer  2102  to a conductive contact  2302  that is connected to ground. Alternatively, the conductive adhesive layer  2300  can be connected to the conductive layer  1810 , and the conductive layer  1810  can be connected to ground. The conductive adhesive can be opaque or transparent, and can be made of any suitable material or materials. One example of a conductive adhesive is a transparent or opaque conductive carbon nanotube adhesive or film. 
       FIG. 24  illustrates another example of a ground connection for the embodiment shown in  FIG. 21 . Conductive material  2400  can connected the layer  2102  to a conductive contact  2402  that is connected to ground. In the illustrated embodiment, the conductive material is formed over a surface of the layer  2102  and in between the stack of layers and the conductive contact  2402 . The conductive material can be any type of conductive material or combination of materials, including, but not limited to, a metal, a nanowire or nanoparticles, or a conductive foam material. In some embodiments, the layer  2102  may shrink or deform over time, so the conductive material  2400  used can be made of a flexible material to compensate for the shrinkage and/or deformation. By way of example only, in some situations the back polarizer  314  in  FIG. 3  can shrink over time, so the conductive material used to connected the back polarizer to ground can be made of a flexible material. 
     Referring now to  FIG. 25 , there is shown another example of a ground connection for the embodiment shown in  FIG. 21 . A flexible cable connector  2500  can be disposed over a surface of the substrate  1900 , and a flexible cable  2502  can be connected to the cable connector  2500 . The flexible cable  2502  can include a trace or signal line that is connected to ground. An electrical connector  2504  can connect the trace or signal line to the layer  2102 . 
     Various embodiments have been described in detail with particular reference to certain features thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the disclosure. For example, the embodiments described in conjunction with  FIGS. 3-5  are not limited to a display layer and a back transparent conductive layer. Electrical connections between two conductive contacts having contact surfaces that are oriented in different directions and disposed over any substrate or substrates, including, but not limited to, metal, plastic, glass, or printed circuit boards, can use embodiments described herein. Additionally or alternatively, embodiments can have or form an electrical connection between three or more conductive contacts. 
     Even though specific embodiments have been described herein, it should be noted that the application is not limited to these embodiments. In particular, any features described with respect to one embodiment may also be used in other embodiments, where compatible. Likewise, the features of the different embodiments may be exchanged, where compatible.

Metadata:
Filing Date: 20140310
Publication Date: 20161227
Grant Date: 20161227
Priority Date: 20130312
Inventors: FARKHONDEH EHSAN
WURZEL JOSHUA G.
TEIL ROMAIN A.
MARTISAUSKAS STEVEN J.
Assignee: APPLE INC
CPC Classifications: [{"code": "H05K3/22", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/108", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13452", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/11", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/1343", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/11", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/13452", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/22", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13452", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/1343", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/1343", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K3/108", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 50478559