Abstract:
A wireless charging coil is provided herein. More specifically, provided herein is a wireless charging coil comprising a first stamped coil having a first spiral trace, the first spiral trace defining a first space between windings, and a second stamped coil having a second spiral trace, the second spiral trace defining a second space between windings, the first stamped coil and second stamped coil in co-planar relation, the first stamped coil positioned within the second space of the second stamped coil, and the second stamped coil positioned within the first space of the first stamped coil, the first and second coils electronically connected and an adhesive covering and surrounding the first stamped coil and the second stamped coil to bond the coils together and to insulate the coils.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation Application of, and claims priority to, U.S. Non-Provisional patent application Ser. No. 14/553,617, filed Nov. 25, 2014, which is Continuation-In-Part (CIP) of, and claims priority to, U.S. Non-Provisional patent application Ser. No. 14/470,381, filed Aug. 27, 2014, which claims the benefit of U.S. Provisional Patent Application No. 61/908,573 filed on Nov. 25, 2013, and U.S. Provisional Patent Application No. 62/004,587 filed on May 29, 2014. U.S. Non-Provisional patent application Ser. No. 14/553,617, filed Nov. 25, 2014 also claims priority to U.S. Provisional Patent Application No. 61/908,573 filed on Nov. 25, 2013, U.S. Provisional Patent Application No. 62/004,587 filed on May 29, 2014, and U.S. Provisional Patent Application No. 62/077,721, filed on Nov. 10, 2014, the entire disclosures of which are expressly incorporated herein by reference. 
    
    
     BACKGROUND 
     Field of the Disclosure 
     The present disclosure relates to a wireless charging coil and methods for manufacturing thereof. More specifically, the present disclosure relates to a bifilar parallel wound, series connected wireless charging coil. 
     Related Art 
     Wireless power transfer is the transfer of electrical power from a base station (transferring power) to a mobile device (consuming power) through electromagnetic induction (inductive power) and/or resonant frequency method. Wireless power transfer is becoming increasingly popular in mobile devices, and particularly in smartphones. A popular standard for inductive charging technology is the Qi interface standard developed by the Wireless Power Consortium, which has several protocols to allow the wireless transfer of electrical power between electronic devices. Other standards may make use of electromagnetic induction or resonant frequency to wirelessly charge devices. A mobile device (or any other electronic device) must meet certain requirements and performance standards in order to be Qi compliant. 
     Consumers generally want their mobile devices to be small and thin but also powerful and efficient, which are often counteracting goals. More specifically, charging coils must vary the material thickness to lower resistance and increase efficiency. Further, maximizing these goals can lead to performance and manufacturing limitations. 
     What would be desirable, but has not yet been developed, is a thinner and more efficient wireless charging coil for wireless power transfer between electronic devices. 
     SUMMARY 
     The present disclosure relates to wireless charging coils and methods for making thereof. More specifically, the present disclosure relates to a planar bifilar parallel-wound, series connected wireless charging coil. The coil has a thinner thickness (e.g., low profile), an increased density (e.g., high fill factor), and higher efficiency (e.g., lower resistance) than conventional wireless charging coils. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing features of the disclosure will be apparent from the following Detailed Description, taken in connection with the accompanying drawings, in which: 
         FIG. 1  is a diagram showing processing steps for manufacturing a wireless charging coil; 
         FIG. 2  is a schematic view of a first stamped coil with tie bars; 
         FIG. 3  is a schematic view of a second stamped coil with tie bars; 
         FIG. 4  is a schematic view of an assembled coil after the tie bars of the first and second stamped coils have been removed; 
         FIG. 5  is a schematic view of the assembled wireless charging coil with jumpers attached; 
         FIG. 6  is a close up view of portion A of  FIG. 5 ; 
         FIG. 7  is a schematic view of an electrical component assembly including a wireless charging coil and NFC antenna; 
         FIG. 8  is a schematic view of an assembled wireless charging coil with planar bifilar coils; 
         FIG. 9  is a cross-sectional view of a portion of the wireless charging coil of  FIG. 8 ; 
         FIG. 10  is a schematic view of an assembled wireless charging coil with stacked bifilar coils; 
         FIG. 11  is a cross-sectional view of a portion of the wireless charging coil of  FIG. 10 ; 
         FIG. 12  is a perspective view of an electrical component assembly; 
         FIG. 13  is an exploded view of the electrical component assembly of  FIG. 12   
         FIG. 14  is a perspective view of a resonant coil; 
         FIG. 15  is a perspective view of a resonant coil assembly; 
         FIG. 16  is a perspective view of a folded stamped resonant coil; 
         FIG. 17  is a perspective view of the coil of  FIG. 16  partially opened; 
         FIG. 18  is a perspective view of the coil of  FIG. 16  fully opened; 
         FIG. 19  is an exploded view of a low profile electrical component assembly; and 
         FIG. 20  is a perspective view of the filler material of  FIG. 19 ; 
         FIG. 21  is a diagram showing processing steps for manufacturing a wireless charging coil with adhesive; 
         FIG. 22  is a partial cross-sectional view of a first stamped coil when applied to a first laminate; 
         FIG. 23  is a partial cross-sectional view of an assembled coil positioned between a first and second laminate; 
         FIG. 24  is partial cross-sectional view of an assembled coil; 
         FIG. 25  is a partial top view of the assembled coil of  FIG. 24 ; and 
         FIG. 26  is a top view of an assembled coil of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure relates to a wireless charging coil and methods of making same. As discussed in more detail below in connection with  FIGS. 1-7 , the stamped metal wireless charging coil comprises a series of parallel traces connected in a bifilar fashion. In other words, the wireless charging coil includes first and second coils that are parallel, closely spaced, and connected in series such that the first and second coils have parallel currents. The first and second coils could be stacked or planar and connected in series and/or parallel to meet performance requirements (e.g., electrical requirements, power requirements, etc.). The wireless charging coil could be used in any battery powered device, particularly in mobile devices (e.g., smartphones, tablets, watches, etc.). The wireless charging coil can be made to be Qi compliant, but could be adjusted to comply with any wireless transfer protocol. A wireless charging coil with a greater amount of conductive material, such as copper, can be positioned within a given space by varying (e.g., increasing) the thickness of the coil, which increases energy availability. Compared with other wireless charging coils, the wireless charging coils described herein exhibit an increased magnetic coupling effectiveness (e.g., magnetic field strength) and thereby transmit energy at a higher efficiency. 
       FIG. 1  is a diagram showing processing steps  10  for manufacturing a wireless charging coil of the present disclosure. In step  12 , a metal sheet is stamped to form a first coil with tie bars. The metal sheet could be any of a variety of materials suitable for wireless power transfer (e.g., copper, copper alloy, aluminum, aluminum alloy, etc.). In step  14 , a metal sheet (e.g., the same metal sheet or a different metal sheet) is stamped to form a second coil with tie bars. In step  16 , the first coil is stamped to remove the tie bars. In step  18 , the second coil is stamped to remove the tie bars. In step  20 , the first and second coils are assembled together. In step  22 , the assembled coil is applied to a ferrite substrate. In step  24 , jumpers (e.g., leads) are attached to electrically connect the first and second coils in series (e.g., an inside end of the first coil is electrically connected to the outside end of the second coil via a jumper). 
     The steps described above could be interchanged, consolidated, or omitted completely. For example, the coils could be stamped without first forming tie bars, and/or the first and second coils could be applied directly to the ferrite (without being assembled first), etc. Additionally, the coil could be photo-chemically etched or machined instead of stamped, or made by any other suitable manufacturing process. 
       FIG. 2  is a view of a first stamped coil  30  with tie bars. The first coil  30  can be a generally rectangular planar spiral trace  31 , although the trace  31  could form any suitable shape (e.g., circular planar spiral). The dimensions of the coil  30  could vary depending on the application of the coil  30  (e.g., as used in mobile devices, wearable devices, cars, etc.). The coil  30  could be of any suitable thickness, such as between 0.003 in. and 0.020 in., etc., but could be thicker for higher powered applications. The coil  30  could be of any suitable overall dimensions, such as between 0.25 in. and 4 in. in width and/or between 0.25 in. and 4 in. in height. The trace  31  could also be of any suitable dimensions. For example, the trace  31  could be between 0.005 in. and 0.250 in. in width. The dimensions could vary depending on physical and performance requirements of the mobile device (e.g., required frequency). The coil  30  could be made of any suitable material for wireless power transfer, such as, for example, copper, copper alloy, aluminum, aluminum alloy, tempered copper alloy (e.g., C110), etc. 
     The trace  31  of the coil  30  revolves around a center any number of times (e.g., 5, 10, etc.), such as to comply with any inductive or resonant power requirements. The trace  31  spirals to form an inside portion  32  at the center of the coil  30 . As a result, the coil  30  has an inside end  34  and an outside end  36 . The spaces  38  between the trace  31  are configured to be wide enough (e.g., 0.0285 in.) to accommodate the second stamped coil (described in more detail below). Tie bars  40  can be positioned at a plurality of locations throughout these spaces  38  to maintain the general shape of the coil  30  (e.g., prevent unwinding or deformation of the shape), such as during transportation of the coil  30  between locations or between stations. The outside end  36  could extend out at an angle, such as a generally ninety degree angle. The inside end  34  and outside end  36  can be disposed towards the same side of the coil  30 , but could be at any of a variety of locations in the coil  30 . 
       FIG. 3  is a view of a second stamped coil  50  with tie bars. The second coil  50  shares most of the same features and characteristics of the first coil shown in  FIG. 2 . The second coil  50  can be a generally rectangular planar spiral trace  51 , although the trace  51  could form any suitable shape (e.g., circular planar spiral). The dimensions of the coil  50  could vary depending on the application of the coil  50  (e.g., as used in mobile devices, wearable devices, cars, etc.). The coil  50  could be of any suitable thickness, such as between 0.003 in. and 0.020 in., etc., but could be thicker for higher powered applications. The coil  50  could be of any suitable overall dimensions, such as between 0.25 in. and 4 in. in width and/or between 0.25 in. and 4 in. in height. The trace  51  could also be of any suitable dimensions. For example the trace  51  could be between 0.005 in. and 0.250 in. in width. The dimensions could vary depending on physical and performance requirements of the mobile device (e.g., required frequency). The coil  50  could be made of any suitable material for wireless power transfer, such as, for example, copper, copper alloy, aluminum, aluminum alloy, tempered copper alloy (e.g., C110), etc. 
     The trace  51  of the coil  50  revolves around a center any number of times (e.g., 5, 10, etc.), such as to comply with any inductive or resonant power requirements. The trace  51  spirals to form an inside portion  52  at the center of the coil  50 . As a result, the coil  50  has an inside end  54  and an outside end  56 . The spaces  58  between the trace  51  are configured to be wide enough (e.g., 0.0285 in.) to accommodate the first stamped coil  30  (described above). Tie bars  60  can be positioned at a plurality of locations throughout these spaces  58  to maintain the general shape of the coil  50  (e.g., prevent unwinding or deformation of the shape), such as during transportation of the coil  50  between locations or between stations. The outside end  56  does not extend out as with the first coil  30  (but could). The inside end  54  and outside end  56  can be disposed towards the same side of the coil  50 , but could be at any of a variety of locations in the coil  50 . 
       FIG. 4  is a view of an assembled coil  170  after the tie bars of the first and second stamped coils  130 ,  150  have been removed. As shown, the first and second coils  130 ,  150  fit into each other. More specifically, the first coil  130  fits into the space formed between the trace  151  of the second coil  150 , and conversely, the second coil  150  fits into the space formed between the trace  131  of the first coil  130 . However, when assembled, there are small gaps between the trace  131  of the first coil  130  and the trace  151  of the second coil  150  (e.g., 0.003 in., 0.004 in., etc.), as discussed below in more detail. As a result, together the first and second coils  130 ,  150  together form a parallel planar spiral. Also shown, the inside end  134  of the first coil  130  is adjacent to the inside end  154  of the second coil  150 , and the outside end  136  of the first coil  130  is adjacent to the outside end  156  of the second coil  150 . However, the ends could be any relative distance from one another. This stamping method could have an average space width variation of at least approximately 0.003 in. for the assembled coil  170 . The maximum and minimum variance are dependent on the assembled coil  170  dimensions (e.g., overall height and width). 
     The tight tolerances and rectangular cross-sectional shape of the traces  130 ,  131  could result in a fill ratio (e.g., 85%) greater than current industry coils (e.g., 65%), such as wound coils, etched coils, etc. For example, the rectangular cross-sectional shape achieved from stamping (see  FIG. 9  below) provides a potentially greater fill ratio than the circular cross-sectional shape of a round wire (e.g., round copper wire). More specifically, a 0.010 in. diameter insulated round wire (0.009 diameter in. wire with 0.0005 in. insulation) could provide a 65% fill ratio, compared to a stamped coil with a rectangular cross section having a 0.006 thickness and 0.003 spacing gap. Further, the wireless charging coil  170  can operate under higher ambient temperatures than other current industry wires (e.g., Litz wire), and is not susceptible to degradation by vibration, shock, or heat. This is partly because the wireless charging coil  170  is made of a single-monolithic conductor (e.g., not a multi-strand wire). This can be compared to the individual strands of a Litz wire, which has insulation material separating each of the individual wire strands which cannot withstand higher temperatures. 
       FIG. 5  is a view of the assembled wireless charging coil  270  with jumpers attached. Although not shown, a jumper could be attached to the first outside end  236 . As shown, the inside end  234  of the first coil  230  is electrically connected to the outside end  256  of the second coil  250  by a first jumper  274 . These ends  234 ,  256  are relatively proximate to one another, and disposed on the same side of the coil  270  to allow for a short jumper  274 . A second jumper  276  is then used to electrically connect the inside end  254  of the second coil with the mobile device circuitry. The outside end  236  and inside end  254  are relatively proximate and disposed towards the same side of the coil  270 , to provide for a short jumper  276  and for ease of electrical wiring with the electronic device. The result is a pair of parallel, closely spaced coils  230 ,  250  connected in series such that the first and second traces  230 ,  250  have parallel currents (e.g., the currents of each trace are in the same clockwise or counter-clockwise direction). 
     When fully assembled with the other components of the electronic device, the inside portion  272  of the assembled coil  270  is insulated (e.g., by plastic and glue) to ensure proper performance. The assembled wireless charging coil  270  can have any number of windings, depending upon electrical requirements. The wireless charging coil  270  could be used in any battery powered device, such as smartphones. The assembled coil  270  could be of any suitable overall dimensions (e.g., 1.142 in. width and 1.457 in. height, etc.). The coil length could be of any suitable length (e.g., 48.459 in.). 
       FIG. 6  is a close up view of portion A of  FIG. 5 . As shown, there are very small gaps  278  (e.g., voids) between the trace  231  of the first coil  230  and the trace  251  of the second coil  250  (e.g., 0.003 in., 0.004 in., etc.), although there could be increased gaps  280  at the corners to account for the bends in the traces  231 ,  251  (e.g., such that the gap increase alternates). These tight tolerances could result in a fill ratio greater than current industry methods. 
     The assembled wireless charging coil  270  could provide direct current (DC) resistance (ohms), alternating current (AC) resistance, and/or AC/DC resistance ratios at a number of different values depending on the dimensions of the charging coil  270  and material(s) used in construction of the charging coil. The values could be adjusted to achieve high AC/DC ratios to meet induction standards. The coil dimensions could be varied to achieve varying resistance depending on the performance characteristics required. For example, for a resistance of 0.232 ohms using C110 alloy, the traces  230 ,  250  could have a cross section of 0.0001234 in. 2  (e.g., 0.005 in. thickness and 0.0246 in. width, or 0.004 in. thickness and 0.0308 in. width, etc.), and for a resistance of 0.300 ohms using C110 alloy, the traces  230 ,  250  could have a cross section of 0.0000953 in. 2  (e.g., 0.005 in. thickness and 0.019 in. width, or 0.004 in. thickness and 0.0238 in. width, etc.). The stamped wireless charging coil  270  can achieve a high trace thickness and/or high overall aspect ratio compared to other current industry methods (e.g., printed circuit board (PCB) etched coils). 
       FIG. 7  is a view of an electrical component assembly  390  including a wireless charging coil  370 . More specifically, the wireless charging coil  370  is attached to ferrite substrate  392  and in conjunction with a near field communication (NFC) antenna  394  having contact paddles. The wireless charging coil  370  and NFC antenna  394  could have contact pads (e.g., gold) to connect the wireless charging coil  370  and NFC antenna  394  to the circuitry of the mobile device. The assembly comprises a first jumper  374 , a second jumper  376 , and a third jumper  377  connecting the various ends of the coil  370 , as explained above in more detail. There could be a film (e.g., clear plastic) over the wireless charging coil  370  and NFC antenna  394 , with the jumpers  374 ,  376 ,  377  on top of the film and only going through the film at the points of connection. This prevents accidentally shorting any of the electrical connections of the coil  370 . Alternatively, the jumpers  374 ,  376 ,  377  could be insulated so that a film is not needed. To minimize space, the wireless charging coil  370  is within the NFC antenna  394  with jumpers  376 ,  377  that extend to the outside of the NFC antenna  394 . However, the wireless charging coil  370  and jumpers  376 ,  377  could be placed at any location relative to the NFC antenna  394 . 
     The total thickness of the assembly could vary depending on various potential needs and requirements. For example, the jumpers could be 0.05-0.08 mm thick, the film could be 0.03 mm thick, the NFC antenna  394  and coil  370  could be 0.08 mm thick, and the ferrite  392  could be 0.2 mm thick for a total wireless charging coil thickness of approximately 0.36 mm. 
       FIG. 8  is a schematic view of an assembled wireless charging coil  470  with planar bifilar coils. As discussed above, the wireless charging coil  470  includes a first coil  430  (e.g., trace) and a second coil  450  (e.g., trace). The assembled coil  470  is manufactured and operates in the manner discussed above with respect to  FIGS. 1-7 . The first coil  430  and the second coil  450  can have any desired thickness, such as to meet different power requirements. The first coil  430  and second coil  450  could be connected in series or parallel. 
     The width of the first and/or second coil  430 ,  450  could vary along the length of the coil to optimize performance of the assembled wireless charging coil  470 . Similarly, the thickness of the first and second coils  430 ,  450  could change over the length of the coil. For example, the width (and/or thickness) of the first coil  430  could gradually increase (or narrow) from a first end  434  towards a middle of the coil  430 , and the width (and/or thickness) could likewise gradually narrow (or increase) from the middle to the second end  436  of the coil  430  (e.g., a spiral coil of wide-narrow-wide), thereby varying the cross-sectional area throughout. Any variation of width (e.g., cross-section) or thickness could be used, and/or these dimensions could be maintained constant over portions of the coil, according to desired performance characteristics. 
     Additionally (or alternatively), the spaces between the windings of the coil could be varied to optimize performance of the wireless charging coil  470 . For example, the gap width between the traces could be wider towards the outside of the first coil  430  and narrower towards the inside of the first coil  430  (or the opposite). Similarly, the distance between the first coil  430  and second coil  450  in the assembled coil  470  could also be varied to optimize performance. Further, the geometry of the edges of the coil could be varied (e.g., scalloped, castellated, etc.), such as to reduce eddy currents. 
       FIG. 9  is a cross-sectional view of a portion of the wireless charging coil of  FIG. 8 . The first coil  430  comprises sections  414 - 424  and the second coil  450  comprises sections  402 - 412 . As shown, the cross-section of the first coil  430  becomes gradually wider and then narrower from a first end to a second end of the first coil  430 . As a result, sections  414  and  424  are the narrowest (e.g., 0.025 in.), followed by sections  404  and  422  (e.g., 0.030 in.), and sections  418  and  420  are the widest (e.g., 0.035 in.). In the same way, the cross-section of the second coil  450  becomes gradually wider and then narrower from a first end to a second end of the second coil  450 . As a result, sections  402  and  412  are the narrowest, and sections  406  and  408  are the widest. Changes in the dimensions of the cross section of the antenna can likewise be varied in other manners. 
       FIG. 10  is a schematic view of an assembled wireless charging coil  570  with stacked bifilar coils. As discussed above, the wireless charging coil  570  includes a first coil  530  and a second coil  550 . The assembled coil  570  is manufactured and operates in the manner discussed above with respect to  FIGS. 1-7 , as well as that discussed in  FIGS. 8-9 , except that the first and second coils  530 ,  550  are stacked instead of planar. The first coil  530  includes a first end  534  and a second end  536 , and the second coil  550  includes a first end  554  and a second end  556 . Further, varying the skew or offset (e.g., stacking distance) of the first coil  530  relative to the second coil  550  can affect the performance of the wireless charging coil  570 . The first coil  530  and second coil  550  could be connected in series or parallel. 
       FIG. 11  is a cross-sectional view of a portion of the wireless charging coil of  FIG. 10 . This coil  570  is similar to that of  FIGS. 8-9 , including a first coil  530  with sections  514 - 524  and a second coil  550  with sections  502 - 512 , except that the first and second coils  530 ,  550  are stacked instead of planar. 
       FIGS. 12-13  are views showing an electrical component assembly  690 . More specifically,  FIG. 12  is a perspective view of an electrical component assembly  690 . The electrical component assembly  690  comprises a ferrite shield  692 , a pressure sensitive adhesive (PSA) layer  602  positioned on the ferrite shield  692 , an assembled coil  670  (e.g., bifilar coil) positioned therebetween, and jumpers  674 ,  676  positioned on the PSA layer  602 . 
       FIG. 13  is an exploded view of the electrical component assembly  690  of  FIG. 12 . The bifilar coil  670  includes a first coil  630  having an inside end  634  and an outside end  636  interconnected with a second coil  650  having an inside end  654  and an outside end  656 . The inside and outside ends are on the same side of the assembled coil  670  for ease of use and assembly (e.g., minimize the distance to electrically connect the ends). 
     Ferrite shield  692  includes a first hole  696  and a second hole  698  positioned to correlate with the placement of the inside end  634  of the first coil  630  and the inside end  654  of the second coil  650  (e.g., when the coil  670  is placed onto the ferrite shield  692 . Although holes  696 ,  698  are shown as circular, any shape and size openings could be used (e.g., one rectangular opening, etc.). These holes  696 ,  698  facilitate assembly and welding of the electrical component assembly  690 . 
     PSA layer  602  and ferrite shield  692  are similarly sized to one another, and although shown as rectangular, both could be of any shape (e.g., circular). PSA layer secures the relative placement of the assembled coil  670  to the ferrite shield  692 . PSA layer  602  could have adhesive on one or both sides, and could include a polyethylene terephthalate (PET) film area  604  free of adhesive on one or both sides. PET film area  604  facilitates assembly and welding of the electrical component assembly  690   
     PSA layer  602  includes a first hole  606  and a second hole  608  in the PET film area  604  which correlate in position with the placement of the inside end  634  of the first coil  630  and the inside end  654  of the second coil  650  (as well as the first hole  696  and second hole  698  of the ferrite substrate  692 ). Although holes  606 ,  608  are shown as circular, any shape and size openings could be used (e.g., one rectangular opening). Holes  606 ,  608  provide access through the PSA layer  602  to electrically connect jumpers  674 ,  676  with the inside ends  634 ,  654  of the assembled coil  670 . The PET film area  604  facilitates attachment of the jumpers  674 ,  676  to the assembly  690 . 
       FIG. 14  is a perspective view of a resonant coil  730 . Resonant coil  730  could be a generally rectangular planar spiral trace  731 , although the trace  731  could form any suitable shape. The resonant coil  730  includes an inside end  734  and an outside end  736 . The trace  731  is stamped on a strip or sheet of metal (e.g., copper, aluminum, etc.). The dimensions of the coil  730  could vary depending on the application of the coil  730 . The coil  730  could be of any suitable thickness, and of any suitable overall dimensions. The trace  731  could also be of any suitable dimensions. The dimensions could vary depending on physical and performance requirements. The coil  730  could be made of any suitable material for wireless power transfer, such as, for example, copper, copper alloy, aluminum, aluminum alloy, tempered copper alloy (e.g., C110), etc. The gaps between the windings of the trace  731  are larger for a resonant coil than for other types of inductive coils due to performance requirements. 
     Stamping provides a scalable process for high volume production with high yields. The stamped trace  731  is not prone to unwinding and can allow for a thicker trace. This is advantageous compared with other existing technologies. For example, winding wire (e.g., copper) to a specific pattern on a surface is difficult and the wound wire can unwind. Further, etched copper is expensive and could be limited to a maximum thickness (e.g., 0.004 in. thick). 
     The trace  731  of the resonant coil  730  includes a first side  737  and a second side  739  offset from the first side  737  by angled portions  741  of the trace  731 . The angled portions  741  are aligned with one another (e.g., occur along line B-B), and angled in the same direction. In other words, angled portions  741  are all angled toward a particular side of the coil  730  (e.g., towards one side of line A-A), such that a first portion  737  (e.g., upper portion) of the coil  730  is shifted relative to a second portion  739  (e.g., lower portion) of the coil  730 . 
       FIG. 15  is a perspective view of a resonant coil assembly  790 , including the first resonant coil  730  from  FIG. 14 . The resonant coil assembly  790  includes a first coil  730  and a second coil  750 , which are identical to one another (which minimizes manufacturing costs). The resonant coil assembly  790  could be laminated such that the first coil  730  and second coil  750  are laminated to a film  702  (e.g., PET film), such as by an adhesive (e.g., heat activated, pressure sensitive, etc.) to provide more stability in downstream operations. The first coil  730  could be adhered to one side of the film  702  and the second coil  750  could be adhered to the opposite side of the film  702 . 
     The first coil  730  includes an outside end  736  and an inside end  734 , and the second coil  750  includes an outside end  756  and an inside end  754 . The first coil  730  and second coil  750  could be exactly the same size and shape coil, except that the second coil  750  is rotated 180 degrees about line D-D. In this way, the trace  731  of the first coil  730  is positioned between the gap formed by the windings of the trace  751  of the second coil  750  (and vice-versa), except at the angled portions of each coil along line D-D, where the traces cross one another. The inside end  734  of the first coil  730  could be adjacent to (and in electrical connection with) the inside end  754  of the second coil  750 , and the outside end  736  of the first coil  730  could be adjacent to the outside end  756  of the second coil  750 . 
       FIGS. 16-18  are views of a stamped resonant coil  870 .  FIG. 16  is a perspective view of a folded stamped resonant coil  870 . The coil  870  comprises connector sheet  871 , a first set of traces  831  of a first coil portion  830  with ends thereof connected to an edge of the connector sheet  871  at connection points  873 , and a second set of traces  851  of a second coil portion  850  with ends thereof connected to the same edge of the connector sheet  871  at connection points  873 . To create the stamped resonant coil  870 , a (single) sheet of metal is stamped to form the first set of traces  831  and the second set of traces  851  (e.g., such that the arcs of each trace of the first and second sets of traces  831 ,  851  are oriented in the same direction). The ends of the first and second set of traces  831 ,  851  are then connected to the same edge of connector sheet  871  (e.g., insulation material). The connector sheet  871  facilitates wiring of the sets of traces  831 ,  851  to each other, as well as facilitates the connection of the stamped resonant coil  870  to electronic circuitry. The ends of the first and second set of traces  831 ,  851  are then wired to each other, such as by using a series of jumpers and/or traces. For example, the jumpers and/or traces could be in the connector sheet  871  and could run parallel to the connector sheet (and perpendicular to the first and second sets of traces  831 ,  851 ). 
       FIG. 17  is a perspective view of the coil  870  of  FIG. 16  partially opened. As shown, the first set of traces  831  of the first coil portion  830  are bent at connection points  873 .  FIG. 18  is a perspective view of the coil  870  of  FIG. 16  fully opened. As shown, the first set of traces  831  of the first coil portion  830  continue to be bent at connection points  873  until the first coil portion  830  is planar with the second coil portion  850 . Bending of the traces could result in fracturing on the outside surface thereof, in which case, ultrasonic welding could be used to ensure electrical conductivity. Alternatively, the first and second sets of traces  831 ,  851  could connect to opposing edges of the connector sheet  871 , such that bending could not be required. Stamping (and bending) in this way reduces the amount of scrap generated, thereby increasing material utilization. 
       FIG. 19  is an exploded view of a low profile electrical component assembly  990 . More specifically, the low profile electrical component assembly  990  comprises a substrate  992  (e.g., PET layer), a filler material layer  933  (e.g., rubber, foam, durometer, etc.), a coil  930  (e.g., resonant coil), and a protective layer  902 . The protective layer  902  could be partly translucent and could comprise a tab (e.g., for applying or removing). 
       FIG. 20  is a perspective view of the filler material  933  of  FIG. 19 . Filler material  933  comprises grooves  935  which correspond in size and shape to that of the coil  930 . In this way, the coil  930  is nested in filler material  933 , which protects the coil shape from bending and/or deformation. Such an assembly facilitates handling of the coil  930  for subsequent operations. 
       FIG. 21  is a diagram showing processing steps  1000  for manufacturing a wireless charging coil with adhesive (e.g., glue). In step  1002 , a metal sheet is stamped to form a first coil with tie bars. In step  1004 , a metal sheet is stamped to form a second coil with tie bars. In step  1006 , a first coil is applied to a first laminate (e.g., plastic substrate, Transilwrap) with an adhesive layer to adhere thereto. In step  1008 , a second coil is applied to a second laminate (e.g., plastic substrate, Transilwrap) with an adhesive layer to adhere thereto. In step  1010 , the first coil is stamped to remove tie bars. In step  1012 , the second coil is stamped to remove tie bars. Accordingly, the first coil and second coil are fixed in place as a result of the adhesive layer on the plastic laminate. In step  1014  the first coil with the laminate adhered thereto, is assembled with the second coil with the laminate adhered thereto. More specifically, as discussed above, the first coil with a spiral trace fits into the space formed between a trace of a second coil, and conversely, the second coil fits into the space formed between the trace of the first coil, thereby forming an assembled coil. As a result, the assembled coil is positioned between (e.g., sandwiched between) the first laminate and the second laminate. 
     In step  1016 , a heat press is applied to the assembled coil to displace and set the adhesive layer from the first and second laminates. More specifically, the heat applied should be hot enough to melt the adhesive (e.g., more than 220-250° F.), but not hot enough to melt the plastic laminate. The pressure applied pushes the first coil towards the second laminate, such that the adhesive of the second laminate positioned in between the trace of the second coil is displaced and forced between the spaces between the first trace of the first coil and the second trace of the second coil. Squeezing the first and second coils together (e.g., with heat and/or pressure) migrates the adhesive to the spaces in between the traces (e.g., to insulate them from one another). This covers or coats the traces of the first coil and the second coil, and bonds the first coil to the second coil. The pressure, heat, and duration could vary depending on the desired cycle time for manufacturing the assembled coil. It is noted that such a process could result in a planar offset of the first coil from the second coil when assembled together. 
       FIG. 22  is a partial cross-sectional view of a first stamped coil  1130  when applied to a first laminate  1123 . The first laminate  1123  includes an adhesive layer  1127  applied to a surface thereof. When the first stamped coil  1130  is applied to the first laminate  1123 , some of the adhesive  1127  is displaced to the sides, such that the displaced adhesive  1127  accumulates against the sides of the trace  1131  of the first stamped coil  1130 . Accordingly, the adhesive  1127  on the sides and underneath the trace  1131  of the first stamped coil  1130  prevents the trace  1131  from moving relative to the first laminate  1123 . 
       FIG. 23  is a partial cross-sectional view of an assembled coil positioned between a first laminate  1123  and second laminate  1125 . As described above, when assembled, the first coil  1130  with a first trace  1131  fits into the space formed between a second trace  1151  of a second coil  1150 , and conversely, the second coil  1150  fits into the space formed between the first trace  1131  of the first coil  1130 , thereby forming an assembled coil  1170 . As a result, the assembled coil  1170  is positioned between (e.g., sandwiched between) the first laminate  1123  and the second laminate  1125 . This displaces the first adhesive  1127  between the first trace  1131  of the first coil  1130 , and displaces the second adhesive  1129  between the second trace  1151  of the second coil  1150 . 
     When the first and second adhesive layers  1127 ,  1129  are set (e.g., by pressure and/or heat), the adhesive covers the surface of the traces  1131 ,  1151  (e.g., by melting), and acts as an insulator and stabilizer for the traces  1131 ,  1151 . In other words, the first and second coils  1130 ,  1150  are bonded together. This prevents relative movement of the traces  1131 ,  1151 , which prevents the first stamped coil  1130  from contacting the second stamped coil  1150  and shorting out the assembled coil  1170 . As an example, the first and second stamped coils  1130 ,  1150  could each be 0.0125 in. thick, and each adhesive layer  1127 ,  1129  could be 0.0055 in. thick, for a total thickness of 0.0225 in. After pressure and/or heat have been applied, the total thickness could be 0.0205 in., with a total adhesive displacement of 0.002 in. 
       FIGS. 24-25  are partial views of an assembled coil  1170 . More specifically,  FIG. 24  is partial cross-sectional view of an assembled coil  1170 , and  FIG. 25  is a partial top view of the assembled coil  1170  of  FIG. 24 . The assembled coil  1170  comprises (as discussed above) a first coil  1130  with a spiral trace  1131 , which fits into the space formed between a trace  1151  of a second coil  1150 , and conversely, the second coil  1150  fits into the space formed between the trace  1131  of the first coil  1130 . Accordingly, the first and second coils  1130 ,  1150  form a parallel planar spiral. 
     As discussed above, a first laminate  1123  (e.g., Transilwrap) with a first adhesive layer is applied to the first stamped coil  1130 , and a second laminate  1125  (e.g., Transilwrap) with a second adhesive layer applied to the second stamped coil  1150 . As a result, the first and second stamped coils  1130 ,  1150  are positioned between the first and second laminates  1123 ,  1125 . When the first and second coils  1130 ,  1150  are assembled with one another, the adhesive  1127  (dyed black for clarity) is displaced to fill the spaces between the first and second traces  1131 ,  1151 . 
       FIG. 25  shows the displacement of adhesive  1127  when the first coil  1130  and second coil  1150  are assembled. More specifically, the adhesive  1127  (dyed black for clarity) is shown between the first trace  1131  and the second trace  1151 . Further, in the particular example shown, more pressure has been exerted on the left side first and second traces  1131   a ,  1151   a , than the right side traces  1131   b ,  1151   b . As a result, less adhesive  1127  has been displaced on the right side than the left side, thereby making the right side trace  1151   b  less visible than the left side trace  1151   a  (as a result of the black dyed adhesive  1127 ). 
       FIG. 26  is a top view of an assembled coil  1270  of the present disclosure. As discussed above, the assembled coil  1270  comprises a first coil  1230  with a first spiral trace  1231  having an inside end  1234  and an outside end  1236 , a second coil  1250  with a second spiral trace  1251  having an inside end  1254  and an outside end  1256 , a first jumper  1277  attached to the outside end  1236  of the first coil  1230 , a second jumper  1274  attached to the inside end  1234  of the first coil  1230  and the outside end  1256  of the second coil  1250 , and a third jumper  1276  attached to the inside end  1254  of the second coil  1250 . The first and second spiral coils  1230 ,  1250  forming an inside portion  1272 . 
     A laminate  1227  (e.g., film, adhesive film, plastic film, etc.) covers the assembled coil  1270  including the inside portion  1272 . As explained above, the adhesive layer of the laminate  1227  stabilizes the first coil  1230  and second coil  1250  and insulates them. This prevents relative movement of the first and second coil  1230 ,  1250  and prevents the first and second coils  1230 ,  1250  from accidentally contacting one another and shorting out the assembled coil  1270   
     The laminate  1227  could define one or more cutouts. More specifically, the laminate  1227  could define an inside cutout  1223  to provide access to (e.g., expose) the first inside end  1234  of the first coil  1230  and the second inside end  1254  of the second coil  1250 . The laminate  1227  could also define an outside cutout  1225  to provide access to (e.g., expose) the first outside end  1236  of the first coil  1230  and the second outside end  1256  of the second coil  1250 . The first cutout  1223  could extend to substantially of the inside portion  1272 . The assembled coil  1270  (and the first and second coils  1230 ,  1250  thereof) could be of any material and/or style (e.g., A6 style coil). 
     For any of the embodiments discussed above, the wireless charging coil (e.g., bifilar coil) could be constructed and then (e.g., at a different location and/or time) the first and second coils of the wireless charging coil, whether stacked or planar, could be electrically connected to each other in series or parallel depending on electrical requirements. 
     Having thus described the system and method in detail, it is to be understood that the foregoing description is not intended to limit the spirit or scope thereof. It will be understood that the embodiments of the present disclosure described herein are merely exemplary and that a person skilled in the art may make any variations and modification without departing from the spirit and scope of the disclosure. All such variations and modifications, including those discussed above, are intended to be included within the scope of the disclosure.