PATENT DOCUMENT

Publication Number: US-9774087-B2
Application Number: US-201414503024-A
Country: US
Kind Code: B2

Title: Wireless electronic device with magnetic shielding layer

Abstract:
An electronic device may have a housing, electrical components, and other electronic device structures. A display may be mounted in the housing. The display may have a transparent display cover layer and a display layer such as an organic light-emitting diode display layer that is mounted to the underside of the transparent display cover layer. A flexible printed circuit with metal traces may be mounted under the organic light-emitting diode display layer. The metal traces may form coils for a near-field communications inductive loop antenna. A magnetic shielding layer may be interposed between the housing and the flexible printed circuit. The magnetic shielding layer may include a polymer magnetic shielding layer having magnetic material particles embedded in a polymer matrix. The magnetic shielding layer may also have a polymer-binder-free magnetic shielding layer.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing; 
 a display mounted in the housing, wherein the display includes a transparent display cover layer and a display layer mounted under the transparent display cover layer; 
 an antenna layer including metal traces that form an antenna; and 
 a magnetic shielding layer adjacent to the antenna layer, wherein the antenna layer is interposed between the magnetic shielding layer and the display, the magnetic shielding layer includes a polymer magnetic shielding layer having particles of magnetic material embedded in a polymer binder, the magnetic shielding layer includes a polymer-binder-free magnetic shielding layer having a layer of magnetic material, and the polymer magnetic shielding layer is interposed between the polymer-binder-free magnetic shielding layer and the antenna layer. 
 
     
     
       2. The electronic device defined in  claim 1  wherein the display layer comprises an organic light-emitting display layer. 
     
     
       3. The electronic device defined in  claim 1  wherein the antenna layer comprises a flexible printed circuit, the antenna comprises a near-field-communications loop antenna, and the metal traces form coils for the antenna. 
     
     
       4. The electronic device defined in  claim 1  wherein the polymer magnetic shielding layer includes a protrusion. 
     
     
       5. The electronic device defined in  claim 4  further comprising a structure with a surface, wherein the protrusion contacts the surface. 
     
     
       6. The electronic device defined in  claim 1  wherein the metal traces form coils in a near-field communications inductive loop antenna. 
     
     
       7. The electronic device defined in  claim 6  wherein the layer of magnetic material of the polymer-binder-free magnetic shielding layer is formed on a plastic liner and the layer of magnetic material is interposed between the plastic liner and the polymer magnetic shielding layer. 
     
     
       8. The electronic device defined in  claim 7  wherein the antenna layer comprises a flexible printed circuit. 
     
     
       9. The electronic device defined in  claim 8  wherein the display layer comprises an organic light-emitting diode display layer and the particles of magnetic material comprise ferrite particles. 
     
     
       10. An electronic device, comprising:
 a housing; 
 a display mounted in the housing, wherein the display includes a transparent display cover layer and an organic light-emitting diode display layer mounted under the transparent display cover layer; 
 a flexible printed circuit containing coiled metal traces that form a near-field communications inductive loop antenna; and 
 a magnetic shielding layer, wherein the flexible printed circuit is interposed between the magnetic shielding layer and the organic light-emitting diode display layer, the magnetic shielding layer includes a polymer-binder-free magnetic shielding layer and a polymer magnetic shielding layer, the polymer magnetic shielding layer includes particles of magnetic material embedded in a polymer matrix, the polymer-binder-free magnetic shielding layer includes a layer of magnetic material, the polymer-binder-free magnetic shielding layer is formed separately from the polymer magnetic shielding layer, and the polymer magnetic shielding layer is interposed between the polymer-binder-free magnetic shielding layer and the flexible printed circuit. 
 
     
     
       11. The electronic device defined in  claim 1 , further comprising:
 a housing wall with an interior surface and an exterior surface, wherein the exterior surface of the housing wall forms an exterior surface for the electronic device and the polymer magnetic shielding layer includes a protrusion that directly contacts the housing wall and forms a seal with the housing wall. 
 
     
     
       12. The electronic device defined in  claim 1 , wherein the polymer-binder free magnetic shielding layer is formed separately from the polymer magnetic shielding layer. 
     
     
       13. The electronic device defined in  claim 12 , wherein the polymer magnetic shielding layer is smoother than the polymer-binder free magnetic shielding layer. 
     
     
       14. The electronic device defined in  claim 1 , wherein the display layer comprises a display layer selected from the group consisting of: a liquid crystal display layer, an organic light-emitting diode display layer, a plasma display layer, an electrophoretic display layer, and an electrowetting display layer. 
     
     
       15. The electronic device defined in  claim 1 , wherein the polymer-binder-free magnetic shielding layer is a sintered ferrite layer. 
     
     
       16. The electronic device defined in  claim 10 , wherein the polymer-binder-free magnetic shielding layer is a sintered ferrite layer.

Description:
This application claims the benefit of provisional patent application No. 62/005,580, filed May 30, 2014, and provisional patent application No. 62/009,806, filed Jun. 9, 2014 which are hereby incorporated by reference herein in their entireties. 
    
    
     BACKGROUND 
     This relates generally to electronic devices, and, more particularly, to wireless electronic devices that include magnetic shielding layers. 
     Wireless electronic devices include antennas. Magnetic shielding layers can be incorporated into wireless electronic devices to prevent conductive electronic device structures from disrupting antenna operation. For example, a ferrite layer that serves as a magnetic shielding layer can be interposed between an antenna and a metal structure in an electronic device to prevent disruptive eddy currents from being produced in the metal structure during operation of the antenna. 
     It can be challenging to incorporate a ferrite layer into an electronic device. If care is not taken, the ferrite layer will be too large and will adversely affect the size of the electronic device. Ferrite layers may also have rough surfaces and may produce stray particles that can adversely affect the smoothness of overlapping structures. 
     It would therefore be desirable to be able to provide improved arrangements for incorporating ferrite layers into electronic devices. 
     SUMMARY 
     An electronic device may have a housing, electrical components, and other electronic device structures. The electronic device may be a portable electronic device or other electronic equipment. 
     A display may be mounted in the housing. The display may have a transparent display cover layer and a display layer that produces images for a user. The images may be viewed through the display cover layer. The display layer may be an organic light-emitting diode display layer that is mounted to the underside of the transparent display cover layer. 
     A flexible printed circuit may be mounted under the organic light-emitting diode display layer. The flexible printed circuit may contain metal traces that form an antenna. For example, the metal traces may form coils for a near-field communications inductive loop antenna. 
     A magnetic shielding layer may be formed below the flexible printed circuit and antenna. The magnetic shielding layer may be interposed between the antenna and other structures in the device such as a rear housing wall in the housing, electrical components on a printed circuit board, and other conductive device structures. 
     The magnetic shielding layer may include a polymer magnetic shielding layer having magnetic material (e.g., particles of magnetic material) embedded in a polymer matrix (binder). The magnetic shielding layer may include, for example, a polymer ferrite layer having ferrite particles embedded in a polymer matrix. The magnetic shielding layer may also have a polymer-binder-free layer. The polymer-binder-free layer may include magnetic material such as a ferrite material (i.e., the polymer-binder-free layer may be a ferrite layer). The polymer-binder-free ferrite layer (or other polymer-binder free magnetic shielding layer) may have a larger magnetic permeability than the polymer ferrite layer (or other polymer magnetic shielding layer) and may therefore help minimize the thickness of the magnetic shielding layer. The polymer ferrite layer (or other polymer magnetic shielding layer) may provide magnetic shielding while helping to prevent irregular surface features from surface roughness and magnetic material particles associated with the polymer-binder-free ferrite layer (or other polymer-binder-free magnetic shielding layer) from propagating upwards to the organic light-emitting diode display layer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of illustrative circuitry in an electronic device in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of the illustrative electronic device of  FIG. 1  in accordance with an embodiment. 
         FIG. 4  is a cross-sectional side view of illustrative curved display and antenna structures in accordance with an embodiment. 
         FIG. 5  is a cross-sectional side view of illustrative display and antenna structures including a magnetic shielding layer that includes a polymer-binder-free sintered ferrite layer and a polymer ferrite layer in accordance with an embodiment. 
         FIG. 6  is a cross-sectional side view of illustrative display and antenna structures including a magnetic shielding layer that has been formed exclusively from polymer ferrite material in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of illustrative display and antenna structures including a polymer ferrite layer with recessed and protruding portions in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device may be provided with wireless circuitry. The wireless circuitry may include one or more antennas. To minimize device size and address other layout concerns, an antenna may be placed in close proximity to conductive device structures. For example, a near-field communications (NFC) antenna or other antenna may overlap a printed circuit board that is populated with integrated circuits and other electrical components, may overlap metal housing structures such as rear housing wall, or may overlap other conductive device structures. A magnetic shielding layer may be interposed between the antenna and the conductive materials to prevent eddy currents from being induced in the conductive materials during antenna operation. If excessive eddy currents were to develop, the antenna would not be able to operate effectively. 
     The magnetic shielding layer may be formed from a material with a high permeability that serves as a conduit for magnetic field lines and prevents the electromagnetic fields from the antenna from reaching underlying conductive structures where eddy currents might develop. Magnetic shielding materials, which are sometimes referred to as ferrites, may be formed from ferromagnetic compounds of iron oxide and other metal oxides (as an example). Examples of ferromagnetic materials that may be used in forming magnetic shielding include manganese-zinc ferrite, nickel-zinc ferrite, zinc ferrite, barium ferrite, strontium ferrite, cobalt ferrite, iron compounds, nickel compounds, zinc compounds, nickel oxide compounds, zinc oxide compounds, non-metallic ceramic ferromagnetic compounds, rare earth materials, neodymium compounds, yttrium compounds, other rare-earth-based materials, magnetic ceramics, etc. The magnetic shielding layer may include particles of magnetic material such as flakes of magnetic material, magnetic material dust, beads of magnetic material, glass particles (e.g., glass spheres) coated with magnetic material, or other magnetic material particles. 
       FIG. 1  is a perspective view of an illustrative electronic device of the type that may be include a ferrite layer to provide magnetic shielding for an antenna. The antenna may be, for example, a near-field communications antenna operating at 13.56 MHz or other suitable frequency. An electronic device such as electronic device  10  of  FIG. 1  may be a computing device such as a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wristwatch device, a pendant device, a headphone or earpiece device, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment. In the illustrative configuration of  FIG. 1 , device  10  is a portable device such as a cellular telephone, media player, tablet computer, wristwatch device, pendant device, or other portable computing device. Other configurations may be used for device  10  if desired. The example of  FIG. 1  is merely illustrative. 
     Device  10  may have one or more displays such as display  14  mounted in housing structures such as housing  12 . Housing  12  of device  10 , which is sometimes referred to as a case, may be formed of materials such as plastic, glass, ceramics, carbon-fiber composites and other fiber-based composites, metal (e.g., machined aluminum, stainless steel, or other metals), other materials, or a combination of these materials. Device  10  may be formed using a unibody construction in which most or all of housing  12  is formed from a single structural element (e.g., a piece of machined metal or a piece of molded plastic) or may be formed from multiple housing structures (e.g., outer housing structures that have been mounted to internal frame elements or other internal housing structures). 
     Display  14  may be a touch sensitive display that includes a touch sensor or may be insensitive to touch. Touch sensors for display  14  may be formed from an array of capacitive touch sensor electrodes, a resistive touch array, touch sensor structures based on acoustic touch, optical touch, or force-based touch technologies, or other suitable touch sensor components. 
     Display  14  for device  10  may be an organic light-emitting diode display or a display formed using other display technologies (e.g., liquid crystal display technology, electrophoretic display technology, plasma display technology, electrowetting display technology, etc.). 
     Electronic device  10  may include one or more antennas. For example, metal lines  16  may be formed in a loop with one or more coils, as shown in  FIG. 1 . The loop formed from metal lines  16  may form an inductor that serves as a near-field communications inductive loop antenna. There are three turns (coils) in the illustrative inductive loop antenna of  FIG. 1 , but additional turns or fewer turns may be used, if desired. Metal lines  16  may be formed form metal traces on a printed circuit or other conductive structures. 
     A schematic diagram showing illustrative components that may be used in device  10  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may include control circuitry such as storage and processing circuitry  28 . Storage and processing circuitry  28  may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in storage and processing circuitry  28  may be used to control the operation of device  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, application specific integrated circuits, etc. 
     Input-output circuitry  44  may include input-output devices  32 . Input-output devices  32  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  32  may include user interface devices, data port devices, and other input-output components. For example, input-output devices may include touch screens (e.g., a capacitive touch sensor array that overlaps a display), displays without touch sensor capabilities, buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, buttons, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, motion sensors (accelerometers), capacitance sensors, proximity sensors, etc. 
     Input-output circuitry  44  may include wireless communications circuitry  34  for communicating wirelessly with external equipment. Wireless communications circuitry  34  may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas, transmission lines, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Wireless communications circuitry  34  may include radio-frequency transceiver circuitry  90  for handling various radio-frequency communications bands. For example, transceiver circuitry  90  may handle non-near-field communications bands such 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and the 2.4 GHz Bluetooth® communications band, cellular telephone bands or other communications bands between 700 MHz and 2700 MHz, signals at 60 GHz, satellite navigation system signals, etc. 
     Wireless communications circuitry  34  may also have near-field communications transceiver circuitry  120 . Near-field communications circuitry  120  may produce and receive near-field communications signals to support communications between device  10  and a near-field communications reader or other external near-field communications equipment. Near-field communications may be supported using loop antennas (e.g., a loop antenna formed from coils  16  of  FIG. 1 ) to support inductive near-field communications in which a loop antenna in device  10  is electromagnetically near-field coupled to a corresponding loop antenna in a near-field communications reader. Near-field communications links may be formed over distances of 20 cm or less (i.e., these links may involve placing device  10  in the vicinity of the near-field communications reader for effective communications). Near-field communications circuitry  120  may operate at 13.56 MHz or other suitable frequency. 
     Wireless communications circuitry  34  may include antennas  40 . Antennas  40  may be formed using any suitable antenna types. For example, antennas  40  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, hybrids of these designs, etc. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link antenna. In addition to supporting cellular telephone communications, wireless local area network communications, and/or other far-field wireless communications, the structures of antennas  40  may be used in supporting near-field communications. For example, antennas  40  may include a near-field communications inductive loop antenna formed from conductive paths  16  of  FIG. 1 . The loop antenna may be formed under display  14  (as shown in  FIG. 1 ) or may be formed elsewhere in device  10 . Multiple near-field communications antennas may be formed in device  10 , if desired. 
     A cross-sectional side view of illustrative electronic device  10  of  FIG. 1  taken along line  18  and viewed in direction  20  is shown in  FIG. 3 . As shown in  FIG. 3 , display  14  of device  10  may be formed from display layer  126 . Display layer  126  may be a display structure that is mounted under a cover layer such as display cover layer  122  (as an example). Display  14  (display layer  126 ) may be a liquid crystal display, an organic light-emitting diode display, a plasma display, an electrophoretic display, an electrowetting display, a display that is insensitive to touch, a touch sensitive display that incorporates and array of capacitive touch sensor electrodes or other touch sensor structures, or may be any other type of suitable display. Display layer (display)  126  may be formed from a flexible material such as a flexible organic light-emitting diode display substrate carrying an array of organic light-emitting diode pixels or other flexible structures. A flexible polymer layer such as a layer of polyimide may be used, for example, serve as a substrate for an organic light-emitting diode display or other display. It may be desirable to protect display layer  126  from external objects using a layer such as display cover layer  122 , particularly in configurations for device  10  in which display layer  126  is based on a flexible polymer substrate. Display cover layer  122  may be layer of clear glass, a transparent plastic member, a transparent crystalline member such as a sapphire layer, or other clear structure that allows images from display layer  126  to be viewed by a user of device  10  through display cover layer  122 . Display cover layer  122  and display layer  126  may be mounted in housing  12   
     Device  10  may have inner housing structures that provide additional structural support for display  14  and/or that serve as mounting platforms for printed circuits and other structures. Structural internal housing members may sometimes be referred to as housing structures and may be considered to form part of housing  12 . 
     Conductive structures  132  may be mounted within housing  12  under display  14 . Conductive structures  132  may include battery structures, sensors, printed circuits, integrated circuits, metal internal housing structures, etc. For example, conductive structures  132  may include electrical components  136  (e.g., integrated circuits, etc.). Components  136  may be mounted to printed circuits such as printed circuit  134 . Printed circuit  134  may be a rigid printed circuit board (e.g., a printed circuit board formed from fiberglass-filled epoxy or other rigid printed circuit board material) or may be a flexible printed circuit (e.g., printed circuit formed from a sheet of polyimide or other flexible polymer layer). Patterned metal traces within printed circuit board  134  may be used to form signal paths between components  136 . If desired, components such as metal connectors, metal shield cans, and other metal parts may be mounted to printed circuit  134 . 
     Device  10  may include a near-field communications antenna such as antenna  40 . Antenna  40  may be an inductive loop antenna formed from coils of metal traces  16  in printed circuit  128  (see, e.g., coils  16  of  FIG. 1 ). Printed circuit  128  may be a rigid or flexible printed circuit. For example, printed circuit  128  may be a flexible printed circuit that is mounted to the lower surface of display layer  126 . Metal traces  16  may be embedded within the polymer or other dielectric that forms flexible printed circuit  128  or may be formed on the upper or lower surface of the polymer substrate material for flexible printed circuit  128  (see, e.g., illustrative metal traces  16 ′ on the inner surface of flexible printed circuit  128 ). Flexible printed circuit  128  is used to form near-field communications antenna  40 , so flexible printed circuit  128  may sometimes be referred to as an antenna flex, an antenna flexible printed circuit, or an antenna layer. 
     A magnetic shielding layer such as layer  130  (sometimes referred to as a ferrite layer) may be formed under antenna layer  128 . During operation of antenna  40 , electromagnetic fields  138  are generated by antenna  40 . Magnetic shielding layer  130  helps prevent electromagnetic fields  138  from penetrating through to underlying conductive structures  132  such as batteries, electrical components  136 , printed circuit  134 , metal housing structures (e.g., a metal housing structure such as a metal rear housing wall for housing  12  and/or internal metal housing structures), and other conductive structures. By preventing fields  138  from reaching conductive structures  132 , the presence of magnetic shielding layer  130  helps prevent the formation of eddy currents in conductive structures  132  that could adversely affect the performance of near-field communications antenna  40 . 
     As shown in  FIG. 4 , display  14  may, if desired, have a curved shape. For example, display  14  may have a curved display cover layer such as curved cover layer  122 , may have a curved display such as curved display layer  126 , may have a curved antenna layer such as layer  128 , and may have a curved magnetic shielding layer such as layer  130 . 
     One or more ferrite layers or other magnetic shielding materials may be used in forming layer  130 . Ferrite layers may be formed by using rollers to attach a layer of sintered ferrite particles to a polymer liner that serves as a carrier. This type of ferrite layer is free of polymer binder material and is sometimes referred to as a polymer-binder-free ferrite layer, sintered ferrite layer, or polymer-binder-free magnetic shielding layer. The layer of sintered ferrite particles or other magnetic material particles in a polymer-binder-free layer may exhibit a high magnetic permeability, but can sometimes generate contaminant particles and exhibit surface roughness due to the presence of surface score lines. If care is not taken, surface irregularities such as these may create defects in overlapping structures. For example, visible dimples in display layer  126  can be produced, thereby adversely affecting the visual appearance of display  14 . In displays such as illustrative curved display  14  of  FIG. 4 , the layers that make up display  14  are flexible (i.e., soft and pliable) and may therefore be susceptible to deformation from underlying particles and surface roughness. Planar displays that incorporate thin and flexible layers of material to minimize device thickness may also be vulnerable to excessive roughness and particles in layer  130 . 
     Whether display  14  is planar or has a curved shape of the type shown in  FIG. 4 , it is desirable to ensure that the surface of display  14  is not adversely affected by dimples or other artifacts produced by the presence of a rough magnetic shielding layer and/or contaminant magnetic material particles. Surface roughness and particle generation can be minimized by using polymer-based magnetic materials as all or part of magnetic shielding layer  130 . In a polymer-based magnetic shielding layer (e.g., a polymer ferrite), particles of magnetic material (e.g., ferrite particles) are embedded within a polymer matrix (i.e., a polymer binder material that binds the magnetic material particles into a cohesive layer). Plastic molding techniques may be used in forming sheets of the polymer magnetic shielding material. Polymer magnetic shielding layers are smoother and give rise to fewer contaminating particles than sintered (polymer-binder-free) magnetic shielding layers and can therefore help improve the appearance of display  14 . 
     Polymer magnetic shielding layers (e.g., polymer ferrite layers) typically have magnetic permeability values that are at most a third of the magnetic permeability values available from polymer-binder-free magnetic shielding layers (e.g., sintered ferrite layers). As a result, shielding layer thickness will generally be larger for polymer magnetic shielding layers than for polymer-binder-free magnetic shielding layers when used to produce a given amount of magnetic shielding. 
     If desired the thin layer thickness that is achievable using a polymer-binder-free magnetic shielding material may be achieved using a hybrid approach in which magnetic shielding layer  130  is formed from layers of both polymer magnetic shielding material (e.g., polymer ferrite) and polymer-binder-free magnetic shielding material (e.g., sintered ferrite). The polymer shielding layer may be interposed between the polymer-binder-free shielding layer and antenna layer  128 . With this type of approach, the upper shielding layer (i.e., the polymer shielding layer) forms a buffer that helps ensure that display  14  is unaffected by particles and roughness associated with the lower shielding layer (e.g., the sintered ferrite layer). The lower non-polymer shielding layer helps to provide sufficient magnetic permeability to the magnetic shielding layer with minimal thickness. 
       FIG. 5  is a cross-sectional side view of an illustrative hybrid magnetic shielding configuration that may be used for display  14 . As shown in  FIG. 5 , display  14  may include display cover layer  122 . Display layer  126  may be mounted to the inner surface of display cover layer  122  (e.g., using adhesive, etc.). Display layer  126  may be an organic light-emitting diode display or other display. Display cover layer  122  and the other layers of  FIG. 5  may be planar or curved. 
     Magnetic shielding layer  130  may include polymer shielding layer  130 - 1  (e.g., a polymer ferrite layer) and polymer-binder-free layer  130 - 2  (e.g., a sintered ferrite layer). Polymer layer  130 - 1  may have magnetic material particles  129  (e.g., ferrite particles or particles of other magnetic material) embedded in polymer binder (matrix)  131 . Layer  130 - 2  may include a layer of magnetic material such as sintered ferrite material  144  or other magnetic material particles (e.g., ferrite material or other magnetic material that does not include a polymer binder of the type used in polymer magnetic shielding layer  130 - 1 ) on a polymer carrier such as liner  146 . Because layer  130 - 2  is free of polymer binder, layer  130 - 2  may sometimes be referred to as a polymer-binder-free layer, polymer-free magnetic material layer, polymer-binder free magnetic shielding layer, polymer-binder-free ferrite layer, or polymer-free ferrite layer. 
     Antenna layer  128  may include near-field communications inductive loop antenna  40  formed from metal traces  16 . Metal traces for antenna  40  may be embedded within antenna layer  128  or may be formed on the upper or lower surface of antenna layer  128 . 
     Antenna layer  128  may be interposed between magnetic shielding layer  130  and display layer  126 . Layers of adhesive such as illustrative lower adhesive layer  142  and upper adhesive layer  140  may be used in attaching the layers of display  14  together. For example, upper adhesive layer  140  may be used to attach antenna layer  128  to the lower surface of display layer  126  and lower adhesive layer  142  may be used to attach magnetic shielding layer  130  to the lower surface of antenna layer  128 . 
     Polymer-binder-free magnetic shielding layer  130 - 2  may contain particles (e.g., ferrite particles or other particles of magnetic material) and may be characterized by a surface roughness that is larger than polymer magnetic shielding layer  130 - 1 . Accordingly, the presence of polymer shielding layer  130 - 1  between polymer-binder-free shielding layer  130 - 2  and the overlapping display layers in display  14  such as antenna layer  128  and display layer  126  may help to enhance the smoothness of display layer  126 . Polymer magnetic shielding layer  130 - 1  (and if desired, soft structures such as adhesive layers  142  and  140 ) may serve as a buffer that helps prevent bumps arising from particles and surface roughness associated with layer  130 - 2  from propagating upwards to display layer  126 . Layer  130 - 2  has a greater magnetic permeability than polymer layer  130 - 1 , so the presence of layer  130 - 2  helps minimize the overall thickness of magnetic shielding layer  130 . If desired, the total layer thickness of layer  130  may be about 300 microns or less, 200 microns or less, or 100 microns or less, may be in the range of 50-300 microns, 100-250 microns, or may have other suitable thickness values. Polymer magnetic shielding layer  130 - 1  may have a thickness that is greater than the thickness of magnetic shielding layer  130 - 2  or may have a smaller thickness. The thickness of polymer magnetic shielding layer  130 - 1  may be about 10 to 25 microns, may be more than 10 microns, may be less than 50 microns, may be less than 30 microns, or may have other suitable thickness values. The total thickness of layer  130 - 1  and layer  144  may be about 140 microns, may be 130-150 microns, may be more than 100 microns, or may be less than 200 microns (as examples). Layers  130 - 1  and  130 - 2  may be bonded using an interposed layer of adhesive, may be bonded by using heat and/or pressure when attaching layers  130 - 1  and  130 - 2 , may be bonded by molding layer  130 - 1  onto layer  130 - 2 , may be bonded by pressing these layers together after chemical, light, or physical treatment of layer  130 - 1  to form a tacky bonding surface, etc. These techniques may also be used to bond layer  130 - 1  to antenna layer  128  (with or without using interposed adhesive layer  142 ). 
     In the illustrative configuration of  FIG. 6 , magnetic shielding layer  130  has been formed of a single layer of material (e.g., polymer-binder-free ferrite or, preferably, polymer ferrite to reduce visible surface defects). When polymer magnetic shielding material is used in forming layer  130 , the polymer magnetic shielding material may be molded over lines  16 ′ on the lower surface of antenna layer  128 , as shown in  FIG. 6 . The molding process may bond the polymer shielding layer to antenna layer  128  while conformally covering lines  16 ′. This type of attachment process may also be used to attach hybrid magnetic shielding layers such as layer  130  of  FIG. 6  to antenna layer  128 . Polymer magnetic shielding layers may also be molded to antenna layers with embedded traces. 
     If desired, the polymer magnetic shielding material of magnetic shielding layer  130  may be provided with raised portions, depressed portions, or other features. These features may be formed when molding the polymer magnetic shielding material. The molded features may be formed in the polymer magnetic shielding material in a hybrid design of the type shown in  FIG. 5  or in polymer magnetic shielding material in a single-layer design of the type shown in  FIG. 6  in which layer  130  is free of polymer-binder-free layers such as sintered ferrite layers and is formed exclusively of particles of magnetic shielding material in a polymer binder. 
       FIG. 7  shows an illustrative polymer magnetic shielding layer (layer  130 ) that has been provided with molded features. The illustrative molded features of layer  130  of  FIG. 7  include recess  148  and protrusions such as side protrusions  150  and lower surface protrusions  156 . The center of loop antenna  40  may require less magnetic shielding than the portion of antenna  40  in the vicinity of coils  16 . Recesses such as illustrative central recess  148  may therefore be formed in the lower surface of magnetic shielding layer  130  within the center of antenna  40  (i.e., the portion of antenna  40  that is not overlapped by coils  16 ) without reducing the effectiveness of magnetic shielding layer  130 . 
     Recesses such as recess  148  in layer  130  may be used to accommodate internal device structures such as structure  154 . Structure  154  may include one or more electrical components such as sensors, batteries, switches, integrated circuits, or other electrical devices, may include protruding portions of internal housing structures or portions of a housing wall in housing  12 , or may include other device structures. 
     Protrusions in layer  130  may be used to form seals. For example, lateral protrusions  150  may form seals with inner surfaces  152  of housing sidewalls, other walls in housing  12 , or other structures in device  10  that are touched by protrusions  150 . These seals may prevent intrusion of contaminants into the interior of device  10  (e.g., moisture, dust, etc.). Lower protrusions  156  may contact structures  158  (e.g., portions of housing  12 , internal housing structures, electrical components, etc.). Protrusions  156  may form shock-absorbing mounting points for the structures of display  14  (as an example). Other types of features may be formed in layer  130  if desired (e.g., by molding, machining, etc.). The illustrative configuration of  FIG. 7  is merely illustrative. 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20140930
Publication Date: 20170926
Grant Date: 20170926
Priority Date: 20140530
Inventors: CHANG ALVIN T.
SHEDLETSKY ANNA-KATRINA
KARDASSAKIS PETER
TONG KATHERINE E.
Assignee: APPLE INC
CPC Classifications: [{"code": "H05K5/0017", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K7/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/526", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K9/0075", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q7/06", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q7/06", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K5/0017", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K7/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/526", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K9/0075", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q7/00", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 54703529