PATENT DOCUMENT

Publication Number: US-9520643-B2
Application Number: US-201313860437-A
Country: US
Kind Code: B2

Title: Electronic device with foam antenna carrier

Abstract:
Electronic devices may include radio-frequency transceiver circuitry and antenna structures. The antenna structures may include a dielectric carrier such as a foam carrier. The foam carrier may be formed from a material that can withstand elevated temperatures. Metal traces for antennas can be formed on the foam carrier by selectively activating areas on a powder coating with a laser and plating the laser-activated areas. Metal for the antennas may also be formed by attaching layers such as flexible printed circuit layers and metal foil layers to the foam carrier. Solder may be used to attach a coaxial cable or other transmission line, electrical components, and other electrical structures to the metal antenna structures on the foam carrier. The foam carrier may be formed from open cell or closed cell foam. The surface of the foam may be smoothed to facilitate formation of metal antenna structures.

Claims:
What is claimed is: 
     
       1. An antenna, comprising:
 a foam carrier; 
 metal on the foam carrier; 
 a powder coating on the foam carrier, wherein the metal comprises metal traces on the powder coating; 
 solder on the metal; and 
 an additional powder coating formed on the metal traces such that the metal traces are interposed between the powder coating and the additional powder coating. 
 
     
     
       2. The antenna defined in  claim 1  wherein the foam carrier comprises open cell foam. 
     
     
       3. The antenna defined in  claim 1  wherein the foam carrier comprises closed cell foam. 
     
     
       4. The antenna defined in  claim 1  wherein the powder coating comprises laser-activated areas and wherein the metal traces comprises plated metal traces on the laser-activated areas. 
     
     
       5. A method of forming an antenna, comprising:
 depositing a powder on a foam carrier; 
 after depositing the powder on the foam carrier, exposing the deposited powder to a temperature of more than 150° C.; 
 after exposing the deposited powder to the temperature of more than 150° C., selectively exposing areas of the powder to laser light; and 
 plating metal onto the exposed areas following exposure of the areas to the laser light to form metal antenna traces on the foam carrier. 
 
     
     
       6. The method defined in  claim 5  further comprising:
 soldering at least one component to the metal antenna traces using solder. 
 
     
     
       7. The method defined in  claim 6  wherein soldering the component comprises depositing solder paste and exposing the solder paste to a temperature of at least 200° C. 
     
     
       8. The method defined in  claim 5  further comprising:
 before depositing the powder on the foam carrier, inserting a metal insert into the interior of the foam carrier to charge the foam carrier. 
 
     
     
       9. The method defined in  claim 5 , wherein the powder comprises polymer particles and additional metal. 
     
     
       10. The method defined in  claim 5 , wherein the powder comprises laser direct structuring powder.

Description:
BACKGROUND 
     This relates generally to electronic devices, and more particularly, to antennas for electronic devices. 
     Antennas are often formed by depositing metal traces on plastic carriers. Patterned metal traces may, for example, be formed using laser-based techniques. With this approach, a laser is used to activate selected areas on a plastic carrier. Following laser activation, electroplating is used to grow metal traces in the activated areas. 
     The plastic carriers that are used for forming antennas in this way may have dielectric properties that give rise to larger losses than desired. If care is not taken, selection of an inappropriate plastic carrier for an antenna may cause the antenna to experience undesired performance degradation. 
     It would therefore be desirable to be able to provide electronic devices with improved antenna structures. 
     SUMMARY 
     Electronic devices may include radio-frequency transceiver circuitry and antenna structures. The antenna structures may include a dielectric carrier such as a foam carrier. The use of the foam carrier may help optimize antenna performance. The foam carrier may be formed from a material that can withstand elevated temperatures to facilitate formation of patterned metal on the carrier and attachment of conductive structures using solder. 
     Metal traces for antennas can be formed on the foam carrier by selectively activating areas on a powder coating with a laser and plating the laser-activated areas. The powder coating may be applied electrostatically and baked prior to exposure to laser light. After laser light has been selectively applied to the powder coating, an electrochemical deposition process may be used to grow metal traces in the laser-activated areas without growing metal in the areas that were not exposed to laser light. 
     Metal for the antennas may also be formed by attaching layers such as flexible printed circuit layers and metal foil layers to the foam carrier. These layers may be attached to the foam carrier as part of a molding process or following machining or other shaping operations to form a foam carrier of a desired shape. 
     Solder may be used to attach a coaxial cable or other transmission line to the metal antenna structures on the foam carrier. Electrical components such as packaged electrical devices may also be soldered to the metal structures on the foam carrier. An oven may be used to reflow solder paste or soldering operations may be performed using other equipment such as a hot bar tool. 
     The foam carrier may be formed from open cell or closed cell foam. The surface of the foam may be smoothed to facilitate formation of metal antenna structures. A smooth surface may be created by applying a smoothing coating to the carrier or by applying a heat treatment or other smoothing treatment to the carrier. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative electronic device with antenna structures in accordance with an embodiment of the present invention. 
         FIG. 2  is a diagram of an illustrative antenna in accordance with an embodiment of the present invention. 
         FIG. 3  is a cross-sectional side view of an illustrative antenna formed from metal traces on a dielectric carrier in accordance with an embodiment of the present invention. 
         FIG. 4  is a diagram showing equipment and operations involved in forming antenna structures in accordance with an embodiment of the present invention. 
         FIG. 5  is a diagram showing illustrative steps involved in forming antenna structures using laser-based processes in accordance with an embodiment of the present invention. 
         FIG. 6  is a diagram showing illustrative steps involved in forming antenna structures by attaching layers such as layers of metal foil or flexible printed circuit layers to a dielectric carrier in accordance with an embodiment of the present invention. 
         FIG. 7  is a diagram showing how an antenna carrier may be formed from a dielectric material such as closed cell foam in accordance with an embodiment of the present invention. 
         FIG. 8  is a diagram showing how an antenna may be formed from a dielectric material such as open cell foam in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices such as electronic device  10  of  FIG. 1  may be provided with antenna structures such as antenna structures  18 . Antenna structures  18  may include one or more antennas. The antennas can include loop antennas, inverted-F antennas, strip antennas, planar inverted-F antennas, slot antennas, hybrid antennas that include antenna structures of more than one type, or other suitable antennas. Conductive structures for the antennas may, if desired, be formed from patterned metal on dielectric carrier structures. The patterned metal may be formed using laser-based metal deposition techniques or by attaching layers such as layers of metal foil or printed circuit structures to the dielectric carrier structures. Other conductive structures may also be used in forming antenna structures  18  if desired (e.g., conductive housing structures, parts of electronic components, internal support structures, brackets, metal plates, and other conductive internal structures, portions of displays and touch sensors, etc.). 
     Electronic device  10  may be a portable electronic device or other suitable electronic device. For example, electronic device  10  may be a laptop computer, a tablet computer, a somewhat smaller device such as a wrist-watch device, pendant device, headphone device, earpiece device, or other wearable or miniature device, a cellular telephone, or a media player. Device  10  may also be a television, a set-top box, a desktop computer, a computer monitor into which a computer has been integrated, or other suitable electronic equipment. 
     Device  10  may include a housing. The housing, which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of these materials. In some situations, parts of the housing may be formed from dielectric or other low-conductivity material. In other situations, the housing for device  10  or at least some of the structures that make up the housing may be formed from metal elements. 
     Device  10  may, if desired, have a display. The display may be a touch screen that incorporates capacitive touch electrodes. The display may include image pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrowetting pixels, electrophoretic pixels, liquid crystal display (LCD) components, or other suitable image pixel structures. 
     In general, device  10  may include any suitable number of antennas in antenna structures  18  (e.g., one or more, two or more, three or more, four or more, etc.). The antennas in device  10  may be located at opposing first and second ends of an elongated device housing, along one or more edges of a device housing, in the center of a device housing, in other suitable locations, or in one or more of such locations. 
     Antennas in device  10  such as antenna structures  18  may be used to support any communications bands of interest. For example, device  10  may include antenna structures for supporting local area network communications, voice and data cellular telephone communications, global positioning system (GPS) communications or other satellite navigation system communications, Bluetooth® communications, etc. 
     As shown in  FIG. 1 , electronic device  10  may include control circuitry and input-output circuitry  12 . Circuitry  12  may include storage and processing circuitry. The storage and processing circuitry 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 control circuitry  12  may be used to control the operation of device  10 . The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio codec chips, application specific integrated circuits, etc. 
     Control circuitry  12  may be used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, control circuitry  12  may be used in implementing communications protocols. Communications protocols that may be implemented using control circuitry  12  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols, etc. 
     Circuitry  12  may be configured to implement control algorithms that control the use of antennas in device  10 . For example, circuitry  12  may perform signal quality monitoring operations, sensor monitoring operations, and other data gathering operations and may, in response to the gathered data and information on which communications bands are to be used in device  10 , control which antenna structures within device  10  are being used to receive and process data and/or may adjust one or more switches, tunable elements, or other adjustable circuits in device  10  to adjust antenna performance. As an example, circuitry  12  may control which of two or more antennas is being used to receive incoming radio-frequency signals, may control which of two or more antennas is being used to transmit radio-frequency signals, may control the process of routing incoming data streams over two or more antennas in device  10  in parallel, may tune an antenna to cover a desired communications band, etc. 
     In performing these control operations, circuitry  12  may open and close switches, may turn on and off receivers and transmitters, may adjust impedance matching circuits, may configure switches in front-end-module (FEM) radio-frequency circuits that are interposed between radio-frequency transceiver circuitry and antenna structures (e.g., filtering and switching circuits used for impedance matching and signal routing), may adjust switches, tunable circuits, and other adjustable circuit elements that are formed as part of an antenna or that are coupled to an antenna or a signal path associated with an antenna, and may otherwise control and adjust the components of device  10 . 
     Input-output circuitry in circuitry  12  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. The input-output circuitry may include input-output devices. The input-output devices may include touch screens, buttons, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, speakers, tone generators, vibrators, cameras, sensors, light-emitting diodes and other status indicators, data ports, etc. A user can control the operation of device  10  by supplying commands through input-output devices and may receive status information and other output from device  10  using the output resources of input-output devices. 
     Wireless communications circuitry such as radio-frequency transceiver circuitry  14  may be formed from one or more integrated circuits and may include power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas, filters, duplexers, and other circuitry for handling RF wireless signals. 
     Circuitry  14  may include satellite navigation system receiver circuitry such as Global Positioning System (GPS) receiver circuitry (e.g., for receiving satellite positioning signals at 1575 MHz) or satellite navigation system receiver circuitry associated with other satellite navigation systems. Wireless local area network transceiver circuitry in circuitry  14  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and may handle the 2.4 GHz Bluetooth® communications band. Circuitry  14  may include cellular telephone transceiver circuitry for handling wireless communications in cellular telephone bands such as bands in frequency ranges of about 700 MHz to about 2700 MHz or bands at higher or lower frequencies. Wireless communications circuitry such as radio-frequency transceiver circuitry  14  can include circuitry for other short-range and long-range wireless links if desired. For example, circuitry  14  may include wireless circuitry for receiving radio and television signals, paging circuits, etc. Near field communications may also be supported (e.g., at 13.56 MHz). In WiFi® and Bluetooth® links and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. In cellular telephone links and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles. 
     The wireless communications circuitry of device  10  may include antenna structures  18 . Antenna structures  18  may be formed using any suitable antenna types. For example, antenna structures  18  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, dual arm inverted-F antenna structures, closed and open slot antenna structures, planar inverted-F antenna structures, helical antenna structures, strip antennas, monopoles, dipoles, 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 structures in device  10  may be provided with one or more antenna feeds, fixed and/or adjustable components such as components  20 , and optional parasitic antenna resonating elements so that the antenna structures cover desired communications bands. Components  20  may include integrated circuits, discrete components such as capacitors, inductors, and resistors, switches, circuitry for filtering signals, impedance matching circuitry, tunable circuits based on adjustable capacitors, adjustable inductors, and other adjustable circuits, components mounted in surface mount technology packages, and other electrical components. 
     As shown in  FIG. 1 , antenna structures  18  may be coupled to wireless circuitry such as transceiver circuitry  14  and other circuitry using transmission line structures such as transmission line  16 . Transmission line  16  may have positive signal path  16 A and ground signal path  16 B. Paths  16 A and  16 B may be formed from metal traces on rigid printed circuit boards, may be formed from metal traces on flexible printed circuits, may be formed on dielectric support structures such as plastic, glass, and ceramic members, may be formed as part of a cable, or may be formed from other conductive signal lines. Transmission line  16  may be formed using one or more microstrip transmission lines, stripline transmission lines, edge coupled microstrip transmission lines, edge coupled stripline transmission lines, coaxial cables, or other suitable transmission line structures. Circuits such as impedance mating circuits, filters, switches, duplexers, diplexers, and other circuitry may, if desired, be interposed in transmission line  16  and/or formed using components  20  such as components associated with antenna structures  18 . 
     Transmission line  16  may be coupled to an antenna feed for an antenna in antenna structures  18  such as feed  28 .  FIG. 2  is a diagram of an illustrative antenna  18  of the type that may be sued in device  10 . As shown in  FIG. 2 , antenna feed  28 , which may sometimes be referred to as an antenna port, may include positive antenna feed terminal  30  and ground antenna feed terminal  32 . If desired, antenna  18  may have multiple feeds. The configuration of  FIG. 2  in which antenna  18  has a single feed is merely illustrative. 
     Antenna  18  may include an antenna resonating element such as antenna resonating element  34  and an antenna ground such as antenna ground  36 . Return path  26 , which may also be referred to as a short circuit path, may be used to couple main arm  24  of antenna resonating element  34  to antenna ground  36 . Antenna resonating element  34  may be an inverted-F antenna resonating element. Antenna ground  36  may be formed from metal traces on a dielectric carrier, metal housing structures, portions of an electronic component, or other metal structures. Return path  26  may be coupled between main arm  24  of inverted-F antenna resonating element  34  and antenna ground  36  in parallel with antenna feed path  28 . 
     If desired, tunable components such as adjustable capacitors, adjustable inductors, filter circuitry, switches, impedance matching circuitry, duplexers, and other circuitry may be interposed within transmission line path  16  (i.e., between transceiver circuitry  14  and feed  28 ). Tunable components may also be formed within the structures of antenna  18  (see, e.g., components  20  of  FIG. 1 ). For example, a tunable component may be formed within arm  24  or path  26 , may be coupled to antenna resonating element  34 , or may otherwise be incorporated in transmission line  16  and antenna  18 . 
     If desired, antenna  18  may be implemented using a patch antenna, loop antenna, slot antenna, monopole antenna, a hybrid antenna that includes multiple types of antenna structures, or other metal structures. The example of  FIG. 2  in which antenna  18  has been formed using an inverted-F antenna design is merely illustrative. 
     Antenna  18  may be formed from metal antenna structures such as metal traces on a dielectric carrier. The metal traces may be formed directly on the surface of a dielectric carrier such as a foam carrier or patterned metal antenna structures may be formed from a piece of patterned foil or flexible printed circuit material that is attached to a foam carrier (as examples).  FIG. 3  is a cross-sectional side view of antenna  18  in an illustrative configuration in which antenna  18  has patterned metal structures such as metal traces  38  that have been formed on the surface of dielectric carrier  40 . Metal traces  38  may be formed from a metal such as copper, gold, aluminum, other metals, or combinations of these metals. 
     Foam carrier  40  may be formed from an open cell or closed cell foam. For example, carrier  40  may be formed from a foam material that has a dielectric constant of about 1.05 to 1.12. Solid plastics such as solid pieces of polycarbonate (PC), acrylonitrile butadiene styrene (ABS), or a PC/ABS blend, in contrast, may have larger dielectric constants (e.g., about 2.9), and may be more prone to dielectric losses than antennas formed from foam carriers such as foam carrier  40 . 
     To ensure compatibility with efficient processes for depositing patterned metal traces  38 , it may be desirable to form carrier  40  from a foam material that can withstand processing at elevated temperatures (e.g., temperatures above 150° C., temperatures above 175° C., temperatures above 190° C., etc.). As an example, it may be desirable to form carrier  40  from a foam material that can withstand temperatures of 190° C. for fifteen minutes (or other temperatures above 150° C.) to facilitate the formation of metal traces  38  (e.g., using processes that involve the baking of electrostatically applied powder coatings) and that can optionally withstand temperatures of 260° C. (or other temperatures above 200° C.) for reflowing solder. Examples of foam materials that may be used for forming carrier  40  include polymethacrylimide foam, polyamide foam, polyimide foam, and polyurethane foam. Other polymer foams may be used, if desired. 
     The ability to withstand soldering temperatures may allow components such as transmission line cable  16  and electrical component  20  to be soldered to traces  38  using solder  42 . For example, transmission line  16  may be a coaxial cable having a center conductor such as center conductor  44  that is soldered to one of metal traces  38  using solder  42  and having an outer ground conductor such as ground conductor  46  that is soldered to one of metal traces  38  using solder  42 . Component  20 , which may be an integrated circuit, a packaged adjustable or fixed circuit based on one or more inductors, capacitors, and resistors, or other circuitry, or a flexible printed circuit with traces may also be soldered to metal traces  38  using solder  42 . 
       FIG. 4  is a diagram showing how antenna  18  may be formed from a foam carrier. Foam material such as foam block  70  may be machined using machining tool  72  to produce foam carrier  40  in a desired shape. Machining tool  72  may be a computer numerical control (CNC) machine tool or other equipment that uses computer-controlled drills, saws, milling bits, or other equipment to shape foam  70  into carrier  40 . If desired, foam  70  may be molded in a heated press such as thermal molding tool  48  to form carrier  40 . Foam carrier  40  may also be formed by introducing liquid foam precursor material  50  into a mold civility in low-pressure injection molding equipment  52 . 
     After forming foam carrier  40 , patterned metal traces  38  may be deposited on the surface of foam carrier  40 . With one suitable arrangement, laser-based processing techniques are used to form traces  38 . Initially, powder coating equipment  54  may be used to deposit a powder coating onto the surface of foam carrier  40 . Electrostatic power coating techniques may be used in which the power is attracted to the surface of carrier  40  by electrostatic attraction. The powder coating equipment may include a temporary metal insert (e.g., a metal rod or blade) that is inserted into the interior of foam carrier  40  to help charge foam carrier  40  and electrostatically attract the power to the outer surfaces of carrier  40 . Baking equipment (e.g., an oven that raises the temperature of the powder-coated carrier to 150° C. for 15 minutes) may be used to form a smooth coating from the powder. 
     The powder that is used may be based on plastic particles and may include metal suitable for activation by laser light. As an example, the powder that is applied to the surface of carrier  40  may be a laser direct structuring powder (LDS powder) based on polyester particles with metal suitable for activation by application of laser light. 
     Following application of the powder to the surface of carrier  40 , laser-based tool  56  may be used to selectively activate the surface of the powder for subsequent metal growth. Tool  56  may include a laser such as laser  58  that is positioned using computer-controlled positioner  60 . By controlling the position of laser  58 , laser light  62  may be applied in desired areas of LDS powder coating  64  on carrier  40 . The application of laser light activates the coating in the exposed areas so that when carrier  40  is subjected to electroplating in plating tool  66 , metal traces  38  will selectively grow in the activated areas and not in the areas that were not activated by application of the laser light. By depositing metal traces  38  in a pattern that is defined by the pattern of light  62  applied to coating  64  on carrier  40 , desired patterns for antenna structures such as antenna resonating element  34  and antenna ground  36  can be formed. 
     Following formation of patterned traces  38  on carrier  40 , soldering tool  68  (e.g., a reflow oven, a hot bar tool, or other soldering equipment) may be used to solder components  20 , transmission lines  16 , flexible printed circuits, wires, and other conductive structures to metal traces  38 , thereby forming antenna  18 . If desired, the traces on carrier  40  may be used for forming sensor structures such as proximity sensor structures (e.g., electrode structures formed from antenna traces or other traces). In this type of configuration, solder  42  may be used to couple signal lines for a proximity sensor control circuit or other external circuitry to the proximity sensor structures on carrier  40 . 
     Laser-based processing techniques for forming metal traces  38  on carrier  40  for antenna  18  are illustrated in  FIG. 5 . Initially, carrier  40  is formed from a dielectric such as a polymer foam. 
     Following formation of foam carrier  40 , an LDS powder such as powder  64  may be applied to carrier  40 . Powder  64  may cover the exposed outer surfaces of carrier  40 . An oven or other equipment may be used to elevate the temperature of powder  64  and carrier  40  sufficiently to form a smooth coating from powder  64  prior to application of laser light. 
     After forming baked powder coating  64  on carrier  40 , laser equipment  56  can expose the surface of coating  64  to light in selected areas. Carrier  40  and its exposed coating  64  may then be placed in an electrochemical deposition tool (e.g., an electroplating bath). Areas of coating  64  that were not exposed to laser light  62  will not promote metal growth and will therefore remain bare of traces  38 . Areas of coating  64  that were activated by exposure to laser light  62  will promote metal growth during plating operations and will therefore result in the formation of corresponding patterned areas of metal traces  38 . 
     Multiple layers of metal traces may be formed using this type of laser-based processing technique. As shown in  FIG. 5 , for example, one or more additional coatings of powder  64  such as powder coating  64 ′ may be deposited over previously deposited metal traces  38 . Laser light may then be selectively applied to portions of the surface of coating  64 ′ and the exposed coating  64 ′ may be exposed to plating solution to grow an additional layer of patterned metal traces  38 ′. Soldering operations may then be performed to attach components  20 , transmission line  16 , and other circuitry, thereby forming antenna  18  of  FIG. 5 . 
       FIG. 6  shows how a foam carrier may be used to form an antenna in a scenario in which metal antenna traces are formed using a fabrication technique that does not rely on laser-based processing. As shown in  FIG. 6 , metal structures such as layers  74  may be attached to the surfaces of foam carrier material  70  (e.g., a foam block). Layers  74  may include unpatterned (blanket) metal foil layers or patterned metal foil. Layers  74  may also include one or more flexible printed circuits. A flexible printed circuit may be formed from a flexible polymer substrate such as a layer of polyimide or other sheet of polymer having one or more layers of substrate material and one or more layers of patterned metal traces (e.g., antenna traces). Layers  74  may be attached using adhesive or by heating foam material  70  while pressing layers  74  against foam material  70 . Layers  74  may be applied using rollers, may be applied inside a heated mold, or may be applied using other techniques. 
     To shape foam  70  into a desired shape, foam  70  and layers  74  may be inserted into a mold cavity in a heated mold. Components  20  may be soldered to the metal of the foil or the metal of the metal traces using solder  42  before molding foam  70 . After soldering any desired components  20  onto the metal on foam  70 , the heated mold may be used to compress and shape foam  70  and layers  74  into a desired finished shape, thereby forming molded carrier  40  and layers  74  on the surface of carrier  40  for antenna  18 . As shown in  FIG. 6 , there may be seams such as seam  76  at locations where the metal of layers  74  on the opposing upper and lower surfaces of carrier  40  is joined together. To form a satisfactory electrical connection between the joined layers at seam  76 , a bead of solder  42  may be formed that runs along seam  76  (e.g., into the page in the orientation of  FIG. 6 ). Solder  42  may be formed using soldering tool  68  (e.g., a reflow oven, a hot bar tool, etc.). As an example, solder paste may be applied along seam  76 . Following application of the solder paste, an elevated temperature may be applied to reflow the solder paste and form solder  42  along seam  76 . 
     Carrier  40  may be formed from closed cell or open cell foam. In closed cell foam, the polymer that forms the foam surrounds and encloses individual foam gas bubbles. As shown in  FIG. 7 , closed cell foam  70  may be shaped into a desired carrier shape for carrier  40  using machining, molding, or other fabrication techniques. Because foam  70  in the  FIG. 7  example is formed for a closed cell material, the surface of carrier  40  will generally be of sufficient smoothness to allow coating  64  to be deposited and laser processed to form patterned metal traces  38 , as described in connection with  FIG. 4 . 
     In open cell foam, individual gas bubbles in the foam are connected to each other, creating a potentially porous and rough surface following machining. Illustrative techniques suitable for forming antennas  18  from open cell foam are shown in  FIG. 8 . As shown in  FIG. 8 , foam  70  (e.g., open cell foam) may be machined to form open foam carrier structure  40 . In situations in which the gas bubbles in the foam are sufficiently small, laser-based processing techniques of the type described in connection with  FIG. 4  may be used to form patterned metal traces  38  directly on the machined surfaces of carrier  40 . For example, powder coating  64  may be deposited followed by selective activation of desired areas with laser exposure and plating operations to form traces  38  in antenna structures  18 A. If the gas bubbles are not sufficiently small or if additional smoothness is desired on the surface of carrier  40 , carrier  40  may be coated with a smoothing layer (e.g., a layer of polymer such as epoxy or other material) or may be subjected to a heat treatment or other treatment to smooth the surface of carrier  40 . Following application of a smoothing coating or heat treatment of the surface of carrier  40 , carrier  40  will have a smooth outer layer such as outer layer  40 ′. Layer  40 ′ may also be formed by heating foam  70  in a heated mold during molding of carrier  40  from foam  70 . 
     Following formation of smooth coating  40 ′ on carrier  40 , carrier  40  may be processed using laser-based processing techniques of the type described in connection with  FIG. 4 . For example, powder coating  64  may be deposited followed by selective activation of desired areas with laser exposure and plating operations to form traces  38  in antenna structures  18 A. 
     Coated carrier  40  (i.e., carrier  40 ′ with smoothing coating  40 ′) or carrier  40  formed by machining foam  70  without forming coating  40 ′ may be used as a dielectric carrier for antenna structures  18 B. Layers  74  of metal foil and/or flexible printed circuits may be attached to carrier  40  using adhesive, as part of a thermal molding process, or using other attachment mechanisms. Layers  74  may contain metal structures (e.g., patterned metal traces, ground plane structures, foil patterns, unpatterned regions of metal foil, etc.) for forming antenna  18 B. 
     Following formation of antenna structures  18 A or  18 B of  FIG. 8 , components  20 , transmission line  16 , flexible printed circuits, and other circuitry can be attached using solder  42  to form antenna structures  18  for device  10 . 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

Metadata:
Filing Date: 20130410
Publication Date: 20161213
Grant Date: 20161213
Priority Date: 20130410
Inventors: SHIU BOON W.
CHEN CHUN-LUNG
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T29/49016", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49016", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 51686423