PATENT DOCUMENT

Publication Number: US-9972454-B1
Application Number: US-201514867336-A
Country: US
Kind Code: B1

Title: Grounding connections in a tactile switch assembly

Abstract:
An electronic device includes a tactile switch assembly. The tactile switch assembly includes a tactile switch structure. A grounding structure can be included in an electrostatic discharge path in the tactile switch structure. The grounding structure can result in a shorter electrostatic discharge path that minimizes damage caused by an electrostatic discharge event. Additionally, different grounding connectors are disclosed that can attach to a grounded component in the electronic device and to a tactile switch bracket associated with the tactile switch assembly. The grounding connector provides a grounding connection to the tactile switch bracket.

Claims:
What is claimed is: 
     
       1. A tactile switch structure, comprising:
 a switch operative to generate an electrical input; 
 a stiffener mechanically connected to the switch; 
 a first flexible circuit attached to a first surface of the stiffener; 
 a component chamber formed in the stiffener, wherein a portion of the first flexible circuit is exposed in the component chamber; and 
 a grounding structure attached to the exposed portion of the first flexible circuit and electrically connecting the stiffener to the first flexible circuit. 
 
     
     
       2. The tactile switch structure of  claim 1 , wherein:
 the grounding structure comprises a conductive post that is attached to the first flexible circuit with solder; 
 the solder fills at least a portion of the component chamber; and 
 the solder contacts the conductive post and stiffener edges in the component chamber. 
 
     
     
       3. The tactile switch structure of  claim 1 , wherein:
 the grounding structure comprises a conductive post attached to the first flexible circuit by a higher temperature solder; and 
 a lower temperature solder at least partially fills the component chamber and contacts both the conductive post and stiffener edges in the component chamber. 
 
     
     
       4. The tactile switch structure of  claim 3 , wherein the stiffener edges in the component chamber are chamfered. 
     
     
       5. The tactile switch structure of  claim 1 , wherein the stiffener is attached to a trim at least partially adjacent the tactile switch structure, such that the stiffener is electrically connected to the trim. 
     
     
       6. The tactile switch structure of  claim 5 , further comprising a second flexible circuit attached to a second surface of the stiffener. 
     
     
       7. The tactile switch structure of  claim 6 , wherein the grounding structure comprises a wire bond having a first end attached to the second flexible circuit and a second end attached to the first flexible circuit. 
     
     
       8. The tactile switch structure of  claim 7 , wherein the wire bond is encapsulated with a nonconductive material. 
     
     
       9. A grounding structure for an input, comprising:
 a flexible connector having a first and second surface, the first surface attached to a trim that is adjacent a switch associated with the grounding structure; and 
 a stiffener attached to the second surface of the flexible connector; 
 and a grounding element attached to the second surface of the flexible connector and to the stiffner, wherein the grounding element comprises a conductive connector selected from the group consisting of a conductive post, a wire bond, and a wire crush rib; wherein 
 a grounding connection is formed between the trim and the stiffener through the flexible connector. 
 
     
     
       10. The grounding structure of  claim 9 , wherein:
 the stiffener is positioned under the second surface of the flexible connector; and 
 the grounding connection is formed between the trim and the stiffener through the flexible connector and the grounding element. 
 
     
     
       11. An electronic device that includes a tactile switch assembly, comprising:
 a tactile switch bracket associated with the tactile switch assembly; 
 a grounded component adjacent the tactile switch bracket; and 
 a grounding connector attached to the grounded component and to the tactile switch bracket to provide a grounding connection to the tactile switch bracket; 
 a conductive tie bar adjacent a top surface of the tactile switch bracket, a first fastener positioned at a first end of the conductive tie bar, and a second fastener positioned at a second end of the conductive tie bar, wherein the first and second fasteners are positioned between the conductive tie bar and the tactile switch bracket. 
 
     
     
       12. The electronic device of  claim 11 , further comprising a frame positioned above the tactile switch bracket, wherein a first fastener is positioned on or within a surface of the frame that is opposite the tactile switch bracket. 
     
     
       13. The electronic device of  claim 11 , wherein:
 the grounded component includes an extension extending toward the tactile switch bracket; and 
 the tactile switch bracket includes a first opening that is configured to receive a first fastener. 
 
     
     
       14. The electronic device of  claim 13 , further comprising:
 the second fastener configured to secure to the first fastener; and 
 a conductive jumper adjacent a top surface of the tactile switch bracket and having a first end that is attached to the extension and a second end having a second opening configured to receive the first fastener, 
 wherein the grounding connector comprising the extension, the conductive jumper, and the first fastener when the first and second fasteners are secured together. 
 
     
     
       15. The electronic device of  claim 14 , wherein the conductive jumper comprises a metal mesh. 
     
     
       16. The electronic device of  claim 14 , wherein the conductive jumper comprises a flexible circuit. 
     
     
       17. The electronic device of  claim 11 , wherein the grounding connector comprises a spring that is attached to the tactile switch bracket and contacts the grounded component.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a nonprovisional patent application of and claims the benefit of U.S. Provisional Patent Application No. 62/058,053, filed on Sep. 30, 2014, and titled “Electrostatic Discharge In A Biometric Sensor” and U.S. Provisional Patent Application No. 62/215,391, filed Sep. 8, 2015 and titled “Grounding Connections in a Tactile Switch Assembly,” the disclosures of which are hereby incorporated herein by reference in their entireties. 
    
    
     FIELD 
     The described embodiments relate generally to electronic devices. More particularly, the present embodiments relate to a grounding connection in or to a tactile switch assembly. 
     BACKGROUND 
     Electrostatic discharge (ESD) can become problematic in electronic devices. ESD is the sudden flow of electricity between two electrically charged objects. ESD can be caused by static electricity which is often generated through tribocharging. Tribocharging occurs when one material becomes electrically charged after it comes into frictional contact with a different material. So, for example, tribocharging may occur when a user of an electronic device walks on a surface such as a carpet, moves into or out of a fabric seat such as in an automobile or other type of seat, or when the user removes some types of plastic packaging from the electronic device. The sudden discharge of electricity caused by ESD can be damaging to many electronic components, especially microchips. A grounding connection or path is one technique for limiting the damage caused by ESD. Additionally, a grounded component can be used by a second component in an electronic device to improve operations of the second component or to improve signal transmissions that are related to the second component. 
     SUMMARY 
     In one aspect, an electronic device includes a tactile switch assembly that is configured to receive user inputs. The tactile switch assembly can include a tactile switch structure having a switch mechanism, such as a dome switch. The tactile switch structure includes a first flexible circuit attached to a first surface of a stiffener, and a component chamber formed in the stiffener. A portion of the first flexible circuit is exposed in the component chamber. A grounding structure may be attached to the exposed portion of the first flexible circuit to electrically connect the stiffener to the first flexible circuit. The grounding structure provides an electrostatic discharge path between the stiffener and the flexible circuit. 
     In one embodiment, the grounding structure is a conductive post that is soldered to the flexible circuit. The solder contacts the edges of the stiffener in the component chamber. In some embodiments, the conductive post is soldered to the flexible circuit with a higher temperature solder. A lower temperature solder can fill the component chamber and contact the edges of the stiffener. 
     In another embodiment, the grounding structure can be a wire bond. The wire bond may be attached between two portions of the same flexible circuit or of two different flexible circuits. 
     In another aspect, the tactile switch structure may include a flexible circuit and a stiffener. A first surface of the flexible circuit can attach to a trim that is adjacent the tactile switch structure, and a second surface of the flexible circuit may attach to the stiffener. An electrostatic discharge path is formed between the trim and the stiffener through the flexible circuit. In some embodiments, at least one grounding structure can be attached between the second surface of the flexible circuit and the stiffener. An electrostatic discharge path is formed between the trim and the stiffener through the flexible circuit and the at least one grounding structure. As one example, the at least one grounding structure may be a wire crush rib. 
     In some embodiments, a method for forming a grounding structure in a tactile switch structure in an electronic device can include attaching the grounding structure to a first surface of a flexible circuit and deforming the grounding structure by positioning a stiffener below the flexible circuit to create an electrical contact between the stiffener and the grounding structure. The grounding structure may then be welded to the flexible circuit through the stiffener. Welding through the stiffener can cause the grounding structure to attach to the stiffener such that the grounding structure is electrically connected to the stiffener and to the flexible circuit. 
     In yet another aspect, a tactile switch assembly can include a tactile switch bracket that is associated with the tactile switch assembly, a grounded component adjacent the tactile switch bracket, and a grounding connector attached to the grounded component and to the tactile switch bracket to provide a grounding connection to the tactile switch bracket. In one embodiment, a grounding connector can include a fastener that secures an extension of the grounded component and the tactile switch bracket. One example of a fastener is a screw. A grounding connection is provided to the tactile switch bracket through the extension and the fastener. 
     In another embodiment, the grounding connector includes a conductive tie bar that is secured to an extension of the grounded component and to the tactile switch bracket with fasteners. Alternatively, a grounding connector can include a conductive jumper that is secured to an extension of the grounded component and to the tactile switch bracket with fasteners. In other embodiments, the grounding connector may be a leaf spring, a pogo spring, or a flexible circuit that is attached to an extension of the grounded component and to the tactile switch bracket. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1  shows an example electronic device that can include a tactile switch assembly; 
         FIG. 2  shows a side view of one example of a tactile switch assembly; 
         FIG. 3  shows a bottom view of a first tactile switch assembly illustrating a longer electrostatic discharge path; 
         FIG. 4  shows a bottom view of another tactile switch assembly illustrating a shorter electrostatic discharge path; 
         FIG. 5  shows a top view of the tactile switch assembly shown in  FIG. 4 ; 
         FIG. 6  shows a cross-sectional view of the tactile switch assembly taken along line  6 - 6  in  FIG. 5 ; 
         FIG. 7  shows an enlarged view of the area  616  shown in  FIG. 6 ; 
         FIG. 8  shows a first example of a grounding structure; 
         FIG. 9  shows a second example of a grounding structure; 
         FIG. 10  shows another enlarged view of the area  616  shown in  FIG. 6 ; 
         FIGS. 11A-11C  show other enlarged views of the area  616  shown in  FIG. 6 ; 
         FIG. 12  shows another enlarged view of the area  616  shown in  FIG. 6 ; 
         FIG. 13A  shows an electronic device that can include a tactile switch assembly and a support plate that provides a grounding connection for a tactile switch bracket associated with the tactile switch assembly; 
         FIG. 13B  is a cross-sectional view of the electronic device taken along line  13 B- 13 B shown in  FIG. 13A ; 
         FIG. 14  shows a first embodiment of a tactile switch bracket connected to a grounded support plate; 
         FIG. 15  shows a cross-sectional view taken along line  15 - 15  shown in  FIG. 14 ; and 
         FIGS. 16 and 17  show a second embodiment of a tactile switch bracket connected to a grounded support plate. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     The following disclosure relates to a tactile switch assembly in an electronic device. The tactile switch assembly is configured to receive user inputs. For example, the tactile switch assembly may include a dome switch that is activated when a downward force is applied to the tactile switch assembly. Additionally or alternatively, the tactile switch assembly can include a biometric sensor, such as a fingerprint sensor. In some embodiments, the biometric sensor can be positioned below a button and configured to capture biometric data (e.g., a fingerprint) when a user presses the button. 
     In a particular embodiment, an electrostatic discharge (ESD) path is provided in the tactile switch assembly that can reduce the impact of an ESD event on the electrical components in a tactile switch structure in the tactile switch assembly. The ESD path includes a grounding structure, such as a conductive post, that electrically connects a flexible circuit to a stiffener in the tactile switch structure. Alternatively, a grounding structure can electrically connect to two portions of a flexible circuit or to two different flexible circuits. 
     The tactile switch assembly can be associated with a tactile switch bracket in an electronic device. The tactile switch bracket may support the tactile switch assembly or the tactile switch structure. In some embodiments, the tactile switch bracket can be electrically connected to a grounded component in the electronic device. A grounding connector can be attached between the grounded component and the tactile switch bracket to provide a grounding connection to the tactile switch bracket. 
     These and other embodiments are discussed below with reference to  FIGS. 1-29 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these Figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1  illustrates one example of an electronic device that can include a tactile switch assembly. In the illustrated embodiment, the electronic device  100  is implemented as a smart telephone. In other embodiments, the electronic device can be a different type of electronic device. For example, a tactile switch assembly may be included in a laptop computer, a tablet computing device, a gaming device, a remote control device, and a wearable computing device such as a smart watch. 
     The electronic device  100  includes a housing  102  at least partially surrounding a display  104  and one or more input/output (I/O) devices  106 . The housing  102  can form an outer surface or partial outer surface for the internal components of the electronic device  100 , and may at least partially surround the display  104 . The housing  102  can be formed of one or more components connected together, such as a front piece  108  and a back piece  110 . Alternatively, the housing  102  can be formed of a single piece. 
     The display  104  can provide a visual output to the user. In some embodiments, the display  104  may incorporate an input device that is configured to receive touch input, force input, temperature input, and the like. The display  104  can be implemented with any suitable technology, including, but not limited to, a multi-touch sensing touchscreen that uses liquid crystal display (LCD) technology, light emitting diode (LED) technology, organic light-emitting display (OLED) technology, organic electroluminescence (OEL) technology, or another type of display technology. The display  104  may be substantially any size and may be positioned substantially anywhere in the electronic device  100 . 
     In the illustrated embodiment, the I/O device  106  is a button. The button  106  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  106  can be integrated as part of a cover glass of the electronic device. In one embodiment, a tactile switch assembly can be disposed below the button  106 . The tactile switch assembly can provide a tactile switch for the button  106 , and can include other components and features. For example, the tactile switch assembly can include a sensor, such as a fingerprint sensor, a force sensor, a thermal sensor, a light sensor, or a proximity sensor. 
       FIG. 2  shows a side view of one example of a tactile switch assembly. The tactile switch assembly  200  includes a connector  202  electrically connected to one end of a flexible circuit  204  and a tactile switch structure  206  electrically connected to the other end of the flexible circuit  204 . In some embodiments, the tactile switch structure  206  can include a sensor  208  that positioned at a top surface of the tactile switch structure and electrically connected to the flexible circuit  204 . The sensor  208  can be any suitable type of sensor, including, but not limited to, a fingerprint sensor, a force sensor, a light sensor, and a proximity sensor. 
     Additionally, the tactile switch structure  206  can include any suitable tactile switch. For example, the tactile switch can be a dome switch assembly  210  that is positioned at a bottom surface of the tactile switch structure  206  and electrically connected to the flexible circuit  204 . The dome switch assembly  210  can be supported by a support plate  212 . When a force is applied to the tactile switch structure  206  (e.g., by pressing on button  106 ), the dome switch assembly  210  is pressed against the support plate  212 , which can cause the dome switch assembly  210  to compress or deform and activate the switch. Other embodiments can use a different type of switch, such as, for example, a force sensing switch. 
     A user charged with static electricity can cause an ESD event when the user touches or presses the button  106  shown in  FIG. 1 . The current produced by the ESD event may then dissipate through the tactile switch assembly  200 .  FIG. 3  shows a bottom view of the tactile switch assembly illustrating a longer ESD path. In some embodiments, an ESD path  300  can originate in area  302  of the tactile switch assembly  200  and travel along the perimeter of the dome switch  304  to the region  306  of the flexible circuit  204 . The ESD path  300  is a relatively long path shown by a dotted line. The ESD path  300  allows the current produced by an ESD event to potentially impact various components included in the tactile switch assembly  200  and/or the tactile switch structure  206 . 
       FIG. 4  shows a bottom view of another tactile switch assembly illustrating a shorter ESD path. The tactile switch assembly  400  includes a grounding structure  402  that ameliorates ESD events that would otherwise damage the tactile switch assembly  400 . As described below, the grounding structure  402  produces a shorter ESD path  404  to the region  306  of the flexible circuit  204 . The grounding structure  402  is located as close as possible to the region  306  so as to minimize the damage caused by the transmission of an electrical charge during an ESD event. In contrast to the ESD path  300  shown in  FIG. 3 , the ESD path  404  in  FIG. 4  is a shorter ESD path that can reduce the number of electronic components in the tactile switch assembly  400  that are impacted by an ESD event. 
       FIG. 5  shows a top view of the tactile switch assembly shown in  FIG. 4 . The tactile switch assembly  400  includes a trim  500  with an input surface  502  positioned in the trim  500  and over the tactile switch structure. The input surface  502  can be made of any suitable material, including glass, ceramic, sapphire, and plastic. The input surface  502  may be a cover glass, a button, a cap, a switch surface, and so on. The input surface  502  may be touch-sensitive and/or force-sensitive, or otherwise may be associated with a touch sensor and/or force sensor. Additionally, the trim  500  can be made of any suitable material, including metal and plastic, ceramic, and the like. The trim may be electrically conductive and act as a ground for a person touching the input surface in certain embodiments, although this is not necessary or the case in all embodiments. 
       FIG. 6  shows a cross-sectional view of the tactile switch assembly taken along line  6 - 6  in  FIG. 5 . The tactile switch structure  600  includes the input surface  502  attached to the trim  500 , the sensor  208  disposed under the input surface, and the flexible circuit  204  positioned below the sensor  208 . The sensor  208  can be attached to the flexible circuit  204  with an adhesive layer  602 , such as a heat cured epoxy. The flexible circuit  204  can wrap around a stiffener  606  (see  FIG. 2 ). A switch  612  may be located beneath the stiffener  606  and input surface  502 , such that the switch collapses and generates an electrical input when the input surface is touched or pressed. 
     The stiffener  606  can be attached to the flexible circuit  204  overlying the stiffener  606  with an adhesive layer  608  and to the flexible circuit  204  underlying the stiffener  606  with another adhesive layer  610 . The adhesive layers  608  and  610  can be any suitable type of adhesive, such as, for example, a pressure sensitive adhesive (PSA). The stiffener  606  can be attached to the trim  500  using any suitable technique. For example, in one embodiment the stiffener  606  is welded to the trim  500  at several attachment points (not shown). The dome switch  612  is connected to the portion of the flexible circuit  204  that is positioned under the stiffener  606 . A component chamber  614  may be created in an opening in the stiffener  606 . A portion of the flexible circuit is exposed in the component chamber  614 . As is described in more detail below, in one embodiment a grounding structure can be positioned or included in the component chamber  614  and electrically connected to the flexible circuit  204 . 
       FIG. 7  shows an enlarged view of the area  616  shown in  FIG. 6 . A conductive post  700  is positioned within the component chamber  614  and is mounted to the exposed portion of the flexible circuit  204 . In the illustrated embodiment, the conductive post  700  is soldered to the flexible circuit  204  with solder  702 . Other embodiments can attach the conductive post  700  using a different attachment method, such as, for example, a conductive adhesive. In one embodiment, the solder  702  is a higher temperature solder. After the conductive post  700  is attached to the flexible circuit  204  with the higher temperature solder  702 , a lower temperature solder  704  may be introduced into the area of component chamber  614  to at least partially fill the component chamber  614  and contact the conductive post  700 . The lower temperature solder  704  also contacts the edges  706  of the stiffener  606  in the component chamber  614 . In one embodiment, the lower temperature solder  704  is disposed in the component chamber  614  through laser soldering. 
     The lower temperature solder  704  can be selected so as to not affect the higher temperature solder  702 . That is, the lower temperature solder  704  has a lower melting point than the higher temperature solder  702 , so the higher temperature solder  702  is not impacted by the introduction of the lower temperature solder  704  into the component chamber  614 . Thus, the conductive post  700  can remain securely attached to the flexible circuit  204  when the lower temperature solder  704  is introduced into the component chamber  614 . 
     In some embodiments, the edges  706  of the stiffener  606  are chamfered to provide mechanical support to the lower temperature solder  704  and help secure the higher temperature solder  702  in the component chamber  614 . In some embodiments, the stiffener  606  and the conductive post  700  include a material with a low thermal conductivity to retain heat from the soldering operation performed in and around the stiffener  606  and the conductive post  700 . For example, the stiffener  606  and the conductive post  700  may include or be formed with a material such as a  300  series stainless steel. 
     The chamfered edges  706  and the conductive post  700  may be plated with a suitable material to aid in flowing or wetting the lower temperature solder  704  around the conductive post  700  and the chamfered edges  706 . Gold is one example of a suitable material. Because a material such as gold may assist in defining where the lower temperature solder  704  may or may not flow, in one embodiment the surfaces of the chamfered edges  706  may be plated with gold but not the top and bottom surfaces of the stiffener  606 . The stiffener surfaces other than the chamfered edges  706  may be plated with or made of nickel or another suitable material that is less conducive to flowing solder, which can help in containing the lower temperature solder  704  between the chamfered edges  706  and within the area of the component chamber  614  that surrounds the conductive post  700 . In other embodiments, various surfaces may be selectively plated with nickel or other suitable material to define the flow of the lower temperature solder to those surfaces. 
     Additionally, the chamfered edges  706  can assist in mechanically holding or restraining the lower temperature solder  704  in the component chamber  614  and prevent a mechanical load transfer to the flexible circuit  204  and the sensor  208  This may prevent the lower temperature solder  704  from being dislodged from the component chamber  614  due to vibrations or other activity associated with the electronic device. Additionally, the combination of the conductive post  700  and the lower temperature solder  704  provide a secure electrical connection that can be mechanically stress free or experience a reduced amount of mechanical stress. 
     In operation, the conductive post  700  is included in an ESD discharge path that begins at the trim  500  and passes through the stiffener  606  to the lower temperature solder  704 , to the conductive post  700 , and to the flexible circuit  204 . Thus, a grounding structure  708  is formed by the combination of the conductive post  700 , the higher temperature solder  702 , and the lower temperature solder  704 . The ESD discharge path may then continue to a grounding trace within, or to a grounding connection connected to, the flexible circuit  204 . This shorter ESD discharge path reduces the possibility that one or more electronic components in the tactile switch assembly are damaged. 
       FIG. 8  shows a first example of a post that can be included in a grounding structure. The post  800  is illustrated as a “top hat” post. The conductive post  800  includes a cylindrical post  802  attached to a larger diameter top portion  804 . The larger diameter top portion  804  can protect the flexible circuit  204  from damage when the top portion  804  is laser soldered or otherwise affixed to the flexible circuit  204 . Additionally or alternatively, since the larger diameter top portion  804  covers more surface area of the flexible circuit  204 , the top portion  804  may also result in a more secure attachment of the conductive post  800  to the flexible circuit  204 . 
       FIG. 9  shows a second example of a conductive post that can be included in a grounding structure. The conductive post  900  is depicted as a conical post. In this embodiment, the top portion  902  has a larger diameter and surface area than the other portions  904  of the conductive post  900 . Like the conductive post  800  shown in  FIG. 8 , the larger diameter top portion  902  can protect the flexible circuit  204  from damage when the conductive post  900  is soldered onto the flexible circuit  204 . Additionally, the larger diameter top portion  902  can result in a more secure attachment of the conductive post  900  to the flexible circuit  204  since the larger diameter top portion  902  covers more surface area of the flexible circuit  204 . In other embodiments, a conductive post can be shaped differently. For example, a conductive post may have a triangular, trapezoidal, or rectangular shape. 
       FIG. 10  shows another enlarged view of the area  616  shown in  FIG. 6 . In another embodiment, a grounding structure  1000  is attached to an upper portion  204 A and lower portion  204 B of the flexible circuit  204 . In the illustrated embodiment, the grounding structure  1000  is a wire bond that may be made of any suitable conductive material, such as gold. One end of the wire bond is attached to the lower portion  204 B of the flexible circuit  204  and the other end is attached to the upper portion  204 A of the flexible circuit  204 . In other embodiments, the upper and lower portions can be two distinct flexible circuits. 
     The upper and lower portions  204 A,  204 B of the flexible circuit  204  may be attached to the stiffener  606  by a conductive adhesive  1002 . The grounding structure  1000  may be encapsulated with a nonconductive material  1004  (shown in dashed lines) so as to prevent the grounding structure  1000  from detaching from the upper and lower portions  204 A,  204 B of the flexible circuit  204 . For example, encapsulating the grounding structure  1000  can prohibit the grounding structure  1000  from detaching from the upper and lower portions  204 A,  204 B when the flexible circuit  204  and/or the electronic device is subjected to strong mechanical forces (e.g., when the electronic device is dropped). In the embodiment shown in  FIG. 10 , the ESD discharge path may begin at the trim  500  and pass through the stiffener  606 , to the lower portion  204 B of the flexible circuit  204 , to the grounding structure  1000 , and to the upper portion  204 A of the flexible circuit  204 . The ESD discharge path may then continue to a grounding trace within, or to a grounding connection connected to, the flexible circuit  204 . 
       FIGS. 11A-11C  show other enlarged views of the area  616  shown in  FIG. 6  that depict another grounding structure. In  FIG. 11A , only the trim  500 , the input surface  502 , and the flexible circuit  204  are shown. A first surface (e.g., top surface) of the flexible circuit  204  is attached to the trim  500  and one or more grounding structures  1100  are attached to a second surface (e.g., bottom surface) of the flexible circuit  204 . In one embodiment, the first surface of the flexible circuit  204  can be attached to the trim  500  with a conductive adhesive (not shown). In the illustrated embodiment, each grounding structure  1100  is configured as a wire crush rib. The one or more wire crush ribs may be formed with gold, copper, or any other suitable material. 
     In  FIG. 11B , the structure of  FIG. 11A  is shown with the stiffener  606  positioned below a second surface of the flexible circuit  204  and contacting the grounding structure(s)  1100  (e.g., the one or more wire crush ribs) to deform the wire crush rib(s) at areas  1102 . The crushing of the one or more wire crush ribs provides some mechanical compliance for the stiffener  606 . Each deformed area  1102  can create an electrical contact between the stiffener  606  and a respective wire crush rib. 
     In  FIG. 11C , the one or more grounding structures  1100  (e.g., the wire crush rib or ribs) can be welded to the flexible circuit  204  at contact points  1104 . In the illustrated embodiment, the grounding structure(s)  1100  are welded to the second surface of the flexible circuit  204  through the stiffener  606 . By heating the stiffener  606 , the wire crush ribs may be made to flow and attach to the stiffener  606 . Thus, the one or more wire crush ribs are affixed and electrically connected to the stiffener  606  and to the flexible circuit  204 . An ESD discharge path may begin at the trim  500 , pass to the flexible circuit  204 , to the one or more grounding structures  1100 , to the stiffener  606 , and to and to another portion of flexible circuit  204  (not shown) that is attached to the stiffener  606 . 
     In other embodiments, a different type of grounding structure can be attached to the flexible circuit and the stiffener. As one example, a conductive contact can be formed on a surface of the stiffener opposite the flexible circuit. The conductive contact can electrically connect to the flexible circuit when the stiffener is positioned adjacent to the flexible circuit. 
       FIG. 12  shows another enlarged view of the area  616  shown in  FIG. 6 . In  FIG. 12 , only the trim  500 , the input surface  502 , the flexible circuit  204 , and the stiffener  606  are depicted. A first surface (e.g., top surface) of the flexible circuit  204  is attached to the trim  500  and a second surface (e.g., bottom surface) of the flexible circuit is attached to the stiffener  606 . In some embodiments, the flexible circuit  204  can be welded to the trim  500  through the stiffener  606 . By welding through the stiffener  606  (e.g., with a laser), the stiffener  606  reflows to form a weld with the flexible circuit  204  and the trim  500 . The ESD discharge path begins at the trim  500 , passes to the flexible circuit  204 , to the stiffener  606 , and to another portion of the flexible circuit  204  (not shown) attached to the stiffener  606 . 
     In some embodiments, the tactile switch assembly can be used to provide or increase the size of a ground plane for an antenna in the electronic device through a grounding connection to the tactile switch assembly. For example, in one embodiment a grounding connection can be provided to a tactile switch bracket that is associated with the tactile switch assembly. In such an embodiment, a grounding connection can extend from one grounded conductive structure in the electronic device to the tactile switch bracket. Any suitable grounded conductive structure can be used, such as, for example, a midplate or a support plate that is positioned under a display (e.g., display  104  in  FIG. 1 ). Additionally, in some embodiments it may be desirable to establish the grounding connection in such a manner that the electronic device may be disassembled and reassembled without permanently destroying the grounding connection. 
       FIG. 13A  shows an electronic device that can include a tactile switch assembly and a grounded support plate that provides a grounding connection for a tactile switch assembly. FIG.  13 B is a cross-sectional view of the electronic device taken along line  13 B- 13 B in  FIG. 13A . The electronic device  1300  includes various electronic components that are connected to a system grounding connection. The ground voltage can act as a reference voltage for some components and/or as a common return path for the components. In the illustrated embodiment, the tactile switch assembly can act as a ground plane for an antenna in the electronic device  1300 . Various embodiments are disclosed herein for a grounded support plate to provide a grounding connection to a bracket of the tactile switch assembly. The grounding connection allows the bracket to act as a ground plane for the antenna. 
     Referring to  FIGS. 13A and 13B , the electronic device  1300  includes a input surface  1302  disposed over a surface of the electronic device  1300 , including a display  1304 . A grounded support plate  1306  is positioned under the display  1304 . The grounded support plate  1306  can mechanically support the display and other components in the electronic device. In some embodiments, the grounded support plate  1306  acts as a heat sink to dissipate heat. Additionally or alternatively, the grounded support plate  1306  can provide a ground and ground reference for a touch input device, such as a touchscreen and act as a ground plane for an antenna  1308 . In the illustrated embodiment, the antenna  1308  is positioned around an interior perimeter of the enclosure  1310  of the electronic device  1300 . 
     As described earlier, a tactile switch assembly can be disposed under the input/output device  1312  (e.g., the button). In some embodiments, the tactile switch assembly can include a tactile switch bracket  1314  that is grounded via a grounding connection  1316  to the grounded support plate  1306 . The grounded tactile switch bracket  1314  can act as a ground plane for the antenna  1308 . 
       FIGS. 14 and 15  show a first embodiment of a tactile switch bracket connected to a grounded support plate. A grounded support plate  1400  is attached to, or includes, an extension  1402  that extends out from the grounded support plate  1400  toward the tactile switch bracket  1406 . The extension  1402  includes an opening (not shown) for a first fastener  1404 . For simplicity, only a portion of the grounded support plate  1400  is shown in  FIG. 14 . The first fastener  1404  is a screw in the illustrated embodiment. A tactile switch bracket  1406  is disposed under a frame  1408 , and includes an opening (not shown) for the first fastener  1404 . The frame  1408  is positioned under the input surface  1302  shown in  FIG. 13 . The exterior surface of the I/O device  1312  (see  FIG. 13A ) is positioned in the opening  1410  of the frame  1408  and the input surface  1302 . 
     A second fastener  1500  (see  FIG. 15 ) configured to secure to the first fastener  1404  is disposed in, or attached to the frame  1408 . In the illustrated embodiment, the second fastener  1500  is a threaded nut that is welded to the frame  1408 . When the first and second fasteners  1404 ,  1500  are secured together, the grounded support plate  1400  and the extension  1402  are secured between the frame  1408  and the tactile switch bracket  1406 . A grounding connection  1502  is provided between the extension  1402  and the grounded support plate  1400  and extends to the bracket  1406  via a grounding connector that includes the extension  1402  and the first fastener  1404 . Thus, the tactile switch bracket  1406  is connected to ground and can act as a ground plane or shield for the antenna  1308  (see  FIG. 13A-13B ). Additionally, the grounding connector can be assembled and disassembled without damage because the first and second fasteners  1404 ,  1500  can be easily coupled and decoupled. 
     In some embodiments, the second fastener  1500  is sub-flush of the top surface of the grounded support plate  1400  to ensure a face-to-face grounding connection between the tactile switch bracket  1406  and the grounded support plate  1400 . A chamfer corner  1504  on the grounded support plate  1400  can isolate the second fastener  1500  from the tactile switch bracket  1406  and the grounded support plate  1400  to prevent a common ground discharge from interfering with the grounding connection  1502 . 
       FIGS. 16 and 17  show a second embodiment of a tactile switch bracket connected to a grounded support plate. A conductive extension  1600  is connected to the grounded support plate  1400 . Any suitable technique can be used to attach the conductive extension  1600  to the grounded support plate  1400 . For example, the extension  1600  can be welded to the grounded support plate  1400  or attached using a conductive adhesive. 
     The extension  1600  extends out from the grounded support plate  1400  toward the tactile switch bracket  1406 . The extension  1600  has an opening (not shown) at one end of the extension  1600  that is configured to receive the first fastener  1404 A. The tactile switch bracket  1406  includes an opening (not shown) to receive the first fastener  1404 B. The second fasteners  1500 A,  1500 B are attached to, or disposed in a conductive tie bar  1604  that is positioned between the input surface  1302  and the tactile switch bracket  1406 . The conductive tie bar  1604  can be embedded in an electrically insulating plastic coating, such as in an overmolded plastic. The embedded tie bar  1604  may be attached to, or buried within, the input surface  1302 . 
     When the first and second fasteners  1404 A,  1500 A and  1404 B,  1500 B are secured to each other, the tactile switch bracket  1406  is secured below the conductive tie bar  1604  and between the first and second fasteners  1404 B,  1500 B. The grounded support plate  1400  provides a grounding connection to the tactile switch bracket  1406  through the extension  1602 , the first and second fasteners  1404 A,  1500 A, the conductive tie bar  1604 , and the first and second fasteners  1404 B,  1500 B. Thus, a grounding connector includes the extension  1600 , the first and second fasteners  1404 A,  1500 A, the conductive tie bar  1604 , and the first and second fasteners  1404 B,  1500 B. The grounding connector can be assembled and disassembled without damage because the first fasteners  1404 A,  1404 B can be easily removed from the second fasteners  1500 A,  1500 B. 
     In addition to the foregoing, various other embodiments may employ different structures for grounding a tactile switch to a plate (support or otherwise) or housing. For example, a conductive jumper may be used; the jumper may be made of any suitable material, such as a sheet metal mesh, stainless steel mesh, or other metal mesh. Further, the conductive jumper may be fully or partly pliable in order to stretch during assembly. In some embodiments, the jumper may be connected to the support plate or an extension thereof by one or more fasteners, which may be removable. Alternately, the jumper may take the form of a flex circuit, coaxial connector, or the like and may be welded, crimped, soldered, or otherwise directly attached to one or both of the bracket and grounding element (e.g., plate or housing), instead of connected by a fastener. 
     As another example, a leaf spring may electrically connect and ground the switch to a plate or housing instead of a jumper. The leaf spring may also form such a connection while retaining some freedom of movement. Accordingly, the leaf spring could maintain the grounding connection while the switch bracket and plate shift or move with respect to one another, for example due to age or as a result of an impact. The leaf spring may be located either below the switch bracket or above it. In the latter example, the leaf spring may be positioned between the switch and the input surface. In yet other embodiments, a pogo spring may be used in lieu of a leaf spring. 
     During installation, the leaf spring may be held away from the grounded support plate by a shim. Upon installation, the shim may be removed to allow the region to be biased against the grounded support plate. The leaf spring itself is self-captured so it is protected from damage during installation. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not target to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20150928
Publication Date: 20180515
Grant Date: 20180515
Priority Date: 20140930
Inventors: COHEN, SAWYER I.
CATER, TYLER B.
CHUNDRU, RAMACHANDRAN
KATIYAR, VIVEK
RAMMAH, MARWAN
SHUKLA, ASHUTOSH Y.
Assignee: APPLE INC
CPC Classifications: [{"code": "H01H2011/0087", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2003/008", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H11/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01H3/12", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01H2207/026", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2207/012", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2205/016", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2239/018", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2239/008", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2207/02", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2207/008", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2231/022", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H13/702", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01H2239/018", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2239/008", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2231/022", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2207/026", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2207/02", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2207/012", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2207/008", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2205/016", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H13/702", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01H3/12", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01H3/12", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 62091396