Patent Description:
A smartcard is an example of an RFID (radio frequency identification) device that has a transponder chip module (TCM) or an antenna module (AM) disposed in a card body (CB) or inlay substrate.

When operating in a contactless mode, a passive antenna module (AM) or transponder chip module (TCM) may be powered by RF from an external RFID reader, and may also communicate by RF with the external RFID reader.

A dual-interface antenna module (AM) or transponder chip module (TCM) may also have a contact pad array (CPA), typically comprising <NUM> or <NUM> contact pads (CP, or "ISO pads") disposed on a "face-up side" or "contact side" (or surface) of the module tape (MT), for interfacing with a contact reader in a contact mode (ISO <NUM>). A connection bridge (CBR) may be disposed on the face-up side of the tape for effecting a connection between two components such as the module antenna and the RFID chip on the other face-down side of the module tape.

A conventional antenna module (AM) or transponder chip module (TCM) may be generally rectangular, having four sides, and measuring approximately <NUM> x <NUM> for a <NUM>-contact module and <NUM> x <NUM> for an <NUM>-contact module. As disclosed herein, a generally rectangular transponder chip module (TCM) may have a larger or smaller form factor than a conventional transponder chip module (TCM). Alternatively, the transponder chip module (TCM) may be round, elliptical, or other non-rectangular shape.

A module antenna (MA) may be disposed on the module tape (MT) for implementing a contactless interface, such as ISO <NUM> and NFC/ISO <NUM>. Contact pads (CP) may be disposed on the module tape (MT) for implementing a contact interface, such as ISO <NUM>. The module antenna (MA) may be wire-wound, or etched, for example:.

A planar antenna (PA) structure, or simply "planar antenna (PA)", whether chemically-etched (CES) or laser-etched (LES), is a type of antenna structure (AS) and may comprise a long conductive trace or track having two ends, in the form of a planar, rectangular spiral, disposed in an outer area of a module tape (MT), surrounding the RFID chip on the face-down side of the module tape. This will result in a number of traces or tracks (actually, one long spiraling trace or track), separated by spaces (actually, one long spiraling space). The track (or trace) width may be approximately <NUM>. The planar antenna may be fabricated on other than the module tape, such as on a separate substrate, and joined to the module tape.

A module antenna (MA) connected to an RFID chip (CM), typically on a substrate or module tape (MT), may be referred to as a "transponder chip module", or simply as a "transponder", or as a "module". Reference may be made to <CIT>, <CIT> and <CIT> for examples of transponder chip modules (and coupling frames).

<CIT>, <CIT> and <CIT> each describe various smartcard constructions and other metal RFID devices. <CIT> discloses, among others, a stacked card body construction consisting of three metal layers each having a slit, the three slits being directed into the same direction (FIG. The metal layers are separated by adhesive layers. Two of the three metal layers have a recess for accepting a transponder chip module. In a similar arrangement (FIGs. <NUM>) the three slits do not overlap but are directed into different directions. The smartcards of the before embodiments are composed of metal card layers being stacked and having the same size. <CIT> discloses in FIG. 13B an RFID device payment object, namely a metal wristband, having an L-shaped slit. <CIT> discloses the principle of coupling frames. <FIG> displays a smartcard having a card body and a metal slug. The slug has an opening for accepting an antenna module and a slit or slot that extends from the opening to the perimeter of the metal slug.

Thus, smartcards made up of stacked coupling frames are known in the art as described before. However, stability of such cards is a problem as the openings for accepting the transponder chip modules and the slits weaken the metal layers.

It is an object of the invention to provide improved metal smartcards.

The object is met by the smartcard according to claim <NUM>. The invention is defined in the claims.

As used herein, a transponder chip module (TCM) may generally comprise an RFID chip and a module antenna disposed on one (face-down) side of a module tape, and contact pads on an opposite (face-up) side of the module tape. In the main, hereinafter, discussions may be directed to passive transponder chip modules operating primarily or exclusively in a contactless mode (e.g., ISO <NUM>, <NUM>). However, the techniques disclosed herein may be applicable to dual-interface transponder chip modules capable of operating in both contactless and contact modes (e.g., ISO <NUM>).

Coupling frames (CF) in combination with transponder chip modules (TCMs) may provide for inductive coupling with a contactless reader or point of sale terminal, or another RFID device. Coupling frames (CF) in combination with transponder chip modules (TCMs) may enhance (including enable) or boost contactless communication between the transponder chip module and a contactless terminal.

Herein, the front card body and the rear card body function as first and second coupling frames, respectively.

As used herein, a "coupling frame" (CF) is a metal layer with an electrical discontinuity in the form of a slit (S) extending from an outer edge of the layer to an inner position thereof, the coupling frame (CF) capable of being oriented so that the slit (S) overlaps (crosses-over) the module antenna (MA) of the transponder chip module (TCM), such as on at least one side thereof. The slit (S) may be straight, and may have a width and a length. The first slit (S) extends to an opening (MO) for accepting the transponder chip module. Coupling frames of this type, typically a layer of metal with an opening for receiving a transponder chip module, and a slit extending from a periphery of the layer to the opening, wherein the slit overlaps at least a portion of the module antenna, may be found in <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>.

The overlap of the slit with the module antenna may be less than <NUM>%. In addition, the width and length of the slit can significantly affect the resonance frequency of the system and may be used as a tuning mechanism. As the width of slit changes, there is a resulting change in the overlap of the slit with the antenna.

In use, the coupling frame may be disposed in close proximity to a transponder chip module, such as atop the module, so that the slit (or other discontinuity) overlaps at least a portion of the module antenna of the transponder chip module, so that the coupling frame enhances (including enables) coupling between the transponder chip module and another RFID device such as a contactless reader. When the slit is not overlapping the antenna, communication with the transponder chip module may be suppressed (or inhibited, including disabled).

In order to satisfy communication requirements for a given smartcard application, in terms of maximum communication read/write range for example, the chip (IC) must have a minimum power level delivered to it. The module antenna (MA) inductance, resistance and capacitance all affect the power level delivered to the chip (IC); at the maximum communication distance from the reader antenna, the module antenna (MA) is delivering the minimum chip (IC) power level. The better the performance of a given module antenna (MA) with a given chip (IC), the greater the maximum communication distance of the transponder chip module (TCM) with respect to the reader antenna.

This disclosure also relates to passive RFID devices operating on the principle of inductive coupling to effectuate data communication and harvest energy with and from a contactless reader and to drive active elements, in particular for integration into payment and identification objects.

According to the invention, generally, a metal smartcard (SC) has a transponder chip module (TCM) with a module antenna (MA), and a card body (CB) comprising two discontinuous metal layers (ML), each layer having a slit (S) overlapping the module antenna, the slits being oriented differently than one another. One metal layer is a front card body (FCB, CF1), and the other layer is a rear card body (RCB, CF2), the rear card body optionally having a magnetic stripe (MS) and/or a signature panel (SP).

The invention focuses on the arrangement of metal layers which are coupling frames, in a card body of a smartcard. Typically, the transponder chip module is added to the smartcard after the card body is already manufactured.

According to the invention, a metal smartcard comprises at least two metal layers, each having a slit (S) and functioning as a coupling frame (CF). The card body of the smartcard comprises:.

The slits (S1, S2) in the various metal layers (CF1, CF2) may each overlap a portion of a module antenna (MA) of the transponder chip module (TCM). The slits of the different metal layers may be oriented or positioned differently than one another so that they are not aligned with one another.

The first metal layer is provided with a recess to accommodate (receive) the second metal layer. The two metal layers may be separated by a layer of non-conductive material, such as an adhesive film.

The second metal layer may form the back of the smartcard, and may contain (support) any or all of a magnetic strips (MS); a signature panel (SP); and a hologram.

One or both of the coupling frames (CF1, CF2) may be connected to a device circuit to power the circuit or improve the read/write performance of the smartcard in conjunction with a reader.

The smartcard and transponder chip module may be passive, harvesting power from an external reader.

The module antenna in the transponder chip module may comprise a planar antenna comprising a single long conductive track laid out in a spiral pattern.

The front card body (FCB) may have a thickness of <NUM> to <NUM>. The rear card body (RCB) may have a thickness of <NUM> to <NUM>.

The resulting smartcard may be operable in both contact and contactless modes. Contact mode would be facilitated by contact pads on the front surface of the smartcard. However, it is generally preferred that the smartcard be intended (and used) only in a contactless mode.

It should be understood that the metal smartcard being described herein is "predominantly" metal, and may include other materials such as protective layers, signature panel, the transponder chip module itself, ink, etc..

Other objects, features and advantages of the invention(s) disclosed herein, and their various embodiments, may become apparent in light of the descriptions of some exemplary embodiments that follows.

Reference will be made in detail to embodiments of the disclosure, non-limiting examples of which may be illustrated in the accompanying drawing figures (FIGs). Some figures may be in the form of diagrams. Some elements in the figures may be exaggerated, others may be omitted, for illustrative clarity.

Any text (legends, notes, reference numerals and the like) appearing on the drawings are incorporated by reference herein.

Some elements may be referred to with letters ("AM", "BA", "CB", "CCM", "CM", "MA", "MT", "PA", "TCM", etc.) rather than or in addition to numerals. Some similar (including substantially identical) elements in various embodiments may be similarly numbered, with a given numeral such as "<NUM>", followed by different letters such as "A", "B", "C", etc. (resulting in "310A", "310B", "310C"), and variations thereof, and may be collectively (all of them at once) or individually (one at a time) referred to simply by the numeral ("<NUM>").

The figures presented herein show different examples of RFID devices, such as smart cards, solid metal cards, plastic hybrid metal cards (also known as embedded metal cards) or payment objects such as wearable devices. Some of the drawings may omit components such as the transponder chip module or module antenna, for illustrative clarity. Some of the figures may show only components of an RFID device, such as coupling frames.

Various embodiments (or examples) may be described to illustrate teachings of the invention(s), and should be construed as illustrative rather than limiting. It should be understood that it is not intended to limit the invention(s) to these particular embodiments. It should be understood that some individual features of various embodiments may be combined in different ways than shown, with one another. Reference herein to "one embodiment", "an embodiment", or similar formulations, may mean that a particular feature, structure, operation, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Some embodiments may not be explicitly designated as such ("an embodiment").

The embodiments and aspects thereof may be described and illustrated in conjunction with systems, devices and methods which are meant to be exemplary and illustrative, not limiting in scope. Specific configurations and details may be set forth in order to provide an understanding of the invention(s). However, it should be apparent to one skilled in the art that the invention(s) may be practiced without some of the specific details being presented herein. Furthermore, some well-known steps or components may be described only generally, or even omitted, for the sake of illustrative clarity. Elements referred to in the singular (e.g., "a widget") may be interpreted to include the possibility of plural instances of the element (e.g., "at least one widget"), unless explicitly otherwise stated (e.g., "one and only one widget").

In the following descriptions, some specific details may be set forth in order to provide an understanding of the invention(s) disclosed herein. It should be apparent to those skilled in the art that these invention(s) may be practiced without these specific details. Any dimensions and materials or processes set forth herein should be considered to be approximate and exemplary, unless otherwise indicated. Headings (typically underlined) may be provided as an aid to the reader, and should not be construed as limiting.

Reference may be made to disclosures of prior patents, publications and applications. Some text and drawings from those sources may be presented herein, but may be modified, edited or commented to blend more smoothly with the disclosure of the present application. Citation or identification of any reference should not be construed as an admission that such reference is available as prior art to the disclosure.

<FIG> is a diagram (cross-sectional view) of a conventional prior-art dual-interface smart card (SC) and readers, as exemplary of an RFID device. This RFID device is "dual interface" since it can interact either with external contact readers (e.g., ISO <NUM>) or with contactless readers (e.g., ISO <NUM>, <NUM>).

The diagram illustrates a smart card SC (<NUM>) in cross-section, along with a contact reader (e.g., ISO <NUM>) and a contactless reader (e.g., ISO <NUM>). An antenna module (AM, or transponder chip module TCM) <NUM> may comprise a module tape (MT) <NUM>, an RFID chip (CM or IC) <NUM> disposed on one side (face-down) of the module tape MT along with a module antenna (MA) <NUM> for interfacing with the contactless reader. The antenna module (AM) may comprise contact pads (CP) <NUM> disposed on the other (face-up) side of the module tape (MT) for interfacing with the contact reader. The card body (CB) <NUM> comprises a substrate which may have a recess (R) <NUM> extending into one side thereof for receiving the antenna module (AM). (The recess R may be stepped - such as wider at the surface of the card body (CB) - to accommodate the profile of the antenna module AM. ) The booster antenna (BA) <NUM> may comprise turns (or traces) of wire (or other conductor) embedded in (or disposed on) the card body CB, and may comprise a number of components such as (i) a card antenna (CA) component <NUM> and (ii) a coupler coil (CC) component <NUM>. It may be noted that, as a result of the recess R being stepped, a portion of the card body (CB) may extend under a portion of the antenna module (AM), more particularly under the module antenna (MA).

In the main, hereinafter, RFID devices having only a contactless interface (and not having a contact interface) may be described. In the main, hereinafter, RFID devices having a coupling frame rather than a booster antenna may be described.

The booster antenna in an RFID device may be eliminated, or replaced by a "coupling frame" (CF). Generally, the overall function of both a booster antenna and a coupling frame are to enhance (improve) coupling and communication between a transponder chip module (TCM) and an external contactless reader (or with another RFID device).

As used herein, a coupling frame (CF) may generally comprise a conductive, planar surface or element (such as a conductive layer, or a conductive foil) having an outer edge, and a discontinuity such as a slit (S) or a non-conductive stripe extending from the outer edge of the conductive surface to an interior position thereof. The coupling frame may be a curved surface, rather than being planar.

The coupling frames described herein have a "continuous" surface, and comprise a sheet or layer of metal having a slit (an electrical discontinuity) for overlapping a module antenna and, in some cases having an appropriate opening (MO) for accommodating mounting the transponder chip module.

When referring to the overall coupling frame as being "continuous", it should be understood that the slit (S) represents a mechanical and electrical discontinuity. A "discontinuous" coupling frame could be made from a solid metal layer, or from embedding wire in a suitable pattern in a substrate, both of which would be arranged to exhibit a slit/discontinuity.

In use, a coupling frame may be disposed closely adjacent to (in close proximity, or juxtaposed with) a transponder chip module (TCM) having a module antenna (MA) so that the slit (S) overlaps (traverses, over or under) at least a portion of the module antenna. For example, the slit (S) may extend from a position external to the module antenna, crossing over (or overlapping) at least some of the traces of the module antenna, such as extending over all of the traces on one side of the module antenna and may further extend into the interior area (no-man's land) of the module antenna.

In use, the coupling frame CF may be positioned so that the slit S overlaps or traverses at least some of the traces of the module antenna MA on at least one side thereof. The slit S may extend at least partially, including completely across only one side of the module antenna, and may extend further across a central area ("no-man's land") of the module antenna (devoid of traces) to the opposite side of the module antenna. The coupling frame and the module antenna may both be substantially planar, positioned very close together, parallel with one another, and separated by an air gap or dielectric layer which may be no greater than <NUM>, <NUM> or <NUM>. Generally, the closer the coupling frame is to the module antenna (smaller separation), the better the communication (such as read/write performance) with the external contactless reader will be. With increasing separation distance, the read/write performance may degrade.

The coupling frame may enhance communication (signal, power) between an external contactless reader and the transponder chip module when the slit is positioned across (to traverse) the traces of the module antenna on at least one side thereof.

Transponder chip modules are conventionally incorporated into RFID devices which are smart cards (including plastic smartcard, metal smartcard, metal veneer smartcard, hybrid smartcard). A coupling frame can be incorporated into the smart card. Refer to <CIT>. A coupling frame may be incorporated into the transponder chip module itself. Refer to <CIT>.

Generally, a transponder chip module (with or without its own coupling frame) can be incorporated into an RFID device such as a smartcard or a payment object. The device may constitute a passive transponder.

A metal layer in a metal hybrid smartcard (aka embedded metal card) may comprise a metal core having two metal layers with slits located in different (including opposite) directions, or otherwise offset from each other (including in the same direction), and said metal layers being electrically insulated by a dielectric such as a screen printed adhesive film or a preassembled adhesive/plastic laminate. Alternatively the metal layer may have recesses milled or etched one side over the area of the slit to accommodate a re-enforcing structure to prevent bending of the finished card around the area of the slit (S).

By incorporating a coupling frame into the device, contactless communication between the RFID chip of the transponder chip module and an external RFID reader or another RFID device may be enhanced or enabled.

Generally, the slit (S) in a coupling frame may be linear (straight) or curved, and may have a width of approximately <NUM> microns, <NUM> microns, <NUM> microns, <NUM> microns, <NUM>-<NUM> and a length of approximately <NUM>-<NUM>, but may have other dimensions and form factors. The slit (S) may be arranged to overlap (traverse) the traces of the module antenna at <NUM>° thereto, or at another angle. The slit (S) may be other than straight.

Generally, the slit (S) may be disguised as part of the card artwork or its presence may be invisible (hidden, rendered inconspicuous) by the application of lacquers and inks. The slit (S) may be widened to enable display of artwork or form a visible decorative feature, the area of the slit may be filled with a decorative panel that may be of different material, texture or colour from other elements of the card.

It should be understood that the coupling frame may be on a different plane than the module antenna. The slit of the coupling frame may overlap or traverse at least some outer turns (or traces) of the module antenna on one side thereof, including overlapping all of the turns of the module antenna on the one side thereof and extending into (above) the inner area (no-man's land) of the module antenna. The slit may be long enough to overlap one or more turns of the module antenna on an opposite side of the module antenna. The slit may be wide enough to overlap one or more inner turns of the module antenna on one or both adjacent side(s) of the module antenna.

<FIG> shows an example which is not part of the invention of a smart card <NUM> with a coupling frame (CF) <NUM> incorporated into its card body (CB) <NUM> which has a stepped recess (R). A transponder chip module (TCM) <NUM> has a planar antenna (PA) which may be a laser-etched antenna structure (LES) <NUM>. The coupling frame (CF) has an opening (MO) <NUM> for receiving the transponder chip module (TCM). The coupling frame (CF) may have a slit (not visible) extending from the opening (MO) to an outer edge of the coupling frame (CF). The dashed line indicates, schematically, that the coupling frame may comprise a metal layer in a stackup of a card body. An inner edge of the coupling frame (CF) may overlap (or underlie) at least some outer turns of the module antenna (MA), which may be a planar antenna (PA) which is laser-etched antenna structure (LES) in the transponder chip module (TCM). Viewed from another perspective, an outer portion of the module antenna (MA may overhang an inner portion of the coupling frame (CF). The coupling frame (CF) may enhance communication between the transponder chip module and another RFID device such as a contactless reader. The transponder chip module may be dual-interface, supporting both contactless and contact communication with external readers.

<FIG> illustrates as a non-claimed example a transponder chip module (TCM) <NUM> disposed in the card body (CB) <NUM> of a metal smartcard (SC) <NUM>, or metal card (MC), wherein substantially the entire card body (e.g., <NUM> thick) comprises metal, and may be referred to as a metal card body (MCB). The transponder chip module (TCM) may reside in an opening (MO) <NUM> extending completely through the card body, the opening may be stepped, having a larger area portion and smaller area portion, as shown. This may result in a void <NUM> behind the transponder chip module (TCM), and the void may be filled with non-conductive filler <NUM>. In a conventional metal smart card (not having a slit to function as a coupling frame), the void behind the transponder chip module may allow electromagnetic radiation from an external reader to interact with the transponder chip module.

A slit (S) <NUM> extends from an outer edge of the metal card body (MCB) to the opening (MO) and may overlap (underneath, as viewed) an outer portion of the module antenna (MA) <NUM> which may be a laser-etched antenna structure (LES). Similarly, a slit may be provided through a metal layer of a hybrid smart card. The slit (S) modifies the metal card body (MCB) or layer, allowing it to operate as a coupling frame <NUM> to enhance contactless communication with the transponder chip module.

<FIG> is illustrative of a coupling frame <NUM> substantially surrounding a transponder chip module and having an opening to accommodate the transponder chip module.

Although a module opening for the transponder chip module may be shown in the illustrations of this and some other embodiments, it should be understood that many of the techniques described herein may be applicable to coupling frames having a slit, without a module opening. Such coupling frames may not be strictly coplanar with the transponder chip module, but they may be disposed closely adjacent and parallel thereto.

Metal payment objects such as metal smart cards may feature a cavity to accommodate the transponder chip module TCM. The cavity may not completely penetrate the payment object, or it may be covered from one face by a continuous metal. The transponder chip module may be shielded from the continuous metal layer by magnetic shielding material. This allows the cavity to be concealed. In addition the slit may be concealed by jewels or crystals.

It is noteworthy that, in some of the figures of prior publications discussed above, such as FIGs. 2C and 2D of <CIT> there is typically a sizeable opening (module opening MO, central opening CO) in the body of the coupling frame to accommodate the transponder chip module, and the slit S in the coupling frame extends from the opening to an outer edge of the coupling frame. This was driven by the form factor of smart cards and the desire to keep the coupling frame as close as possible to the module antenna. The coupling frame was typically substantially coplanar with the module antenna, and typically surrounded it.

As disclosed herein, a second coupling frame CF may be a planar (or non-planar, 3D) conductive element having an outer periphery (edge) and having a slit S extending from its outer edge to an inner location on the conductive element. In the metal smartcard, the coupling frame is disposed (arranged) to overlap a module antenna of the transponder chip module, and may be oriented (arranged) so that the slit S overlaps (traverses over, or under) the turns (traces) of the module antenna on one side thereof. As distinguished from the coupling frames disclosed for example in <CIT> (see also <CIT> and <CIT>), in the second coupling frames disclosed herein the inner end of the slit S need not terminate in a distinct opening sized to accommodate the transponder chip module TCM. Essentially, it is the slit rather than the opening that dictates the electrical characteristics of the coupling frame.

In many of the examples and embodiments presented herein, coupling frames and transponder chip modules may be integrated into payment objects, which may also be referred to as "payment devices", or simply "devices".

<FIG> illustrates the front side of a smartcard (SC) <NUM> which may be a metal card having a metal layer (ML), which may constitute substantially the entire thickness of the card body (CB) <NUM>. The card body (CB) may have a module opening (MO) <NUM> wherein a transponder chip module (TCM) <NUM> may be disposed, and a slit (S) <NUM> extending from the module opening (MO) to the outer perimeter of the metal layer (ML) so that the metal card body (MCB) <NUM> may function as a coupling frame (CF) <NUM>. The metal layer (ML) (or card body CB, or metal card body MCB) may comprise stainless steel, titanium, or any other metal or metal alloy and is provided with a slit, slot or gap in the metal to create an open loop coupling frame (CF) closely adjacent to and substantially fully surrounding the transponder chip module (TCM).

The slit (S) may overlap at least a portion of the module antenna (MA, not shown) of the transponder chip module. In some examples and embodiments of coupling frames incorporated into RFID devices disclosed herein, there may not need to be an opening (MO) in the coupling frame (CF) for the transponder chip module (TCM).

This concept of modifying a metal element to have a slit (S) to function as a coupling frame (CF) may be applied to other products which may have an antenna module (AM) or transponder chip module (TCM) integrated therewith, such as watches, wearable devices, and the like.

The slit (S) may extend completely (fully) through the metal layer (ML) forming the coupling frame (CF). The slit (S) may extend only partially through the metal layer, and remaining material of the metal layer below the slit (S) may have a thickness below a transparency threshold or skin depth for the metal layer. The slit (S) may have a width which is smaller than the opening. The slit (S) may be at least partially filled with an electrically nonconducting material selected from the group consisting of polymer and epoxy resin, reinforced epoxy resin. A reinforcing structure (RS) may be disposed at a location of the slit (S) to reinforce the metal layer (ML).

An activation distance for a transponder chip module (TCM) disposed in (or under, or above) the opening (MO) of the coupling frame may be at least <NUM>; at least <NUM>; at least <NUM>; at least <NUM>; up to <NUM>; and more than <NUM>.

A component element may be connected across the slit such as a capacitor to enhance performance. The transponder chip module may also house a capacitor to improve coupling.

<FIG> are included for illustrative purposes and for explaining general principles implemented in claimed embodiments.

<FIG> illustrates an exploded view of a solid metal smartcard comprising two metal layers (ML) attached together (joined with one another) by an adhesive film (AF) <NUM>. The front card body (FCB) <NUM> composed of a metal layer (ML) contains a first module opening (MO1) <NUM> that accepts a specially designed transponder chip module (TCM) <NUM>. The front card body (FCB) <NUM> may have thickness <NUM> to <NUM>. The rear card body (RCB) <NUM> fits into a pocket milled, etched, stamped or otherwise formed in the rear side of the front card body (FCB) <NUM>. The front card body (FCB) <NUM> comprises a first slit (S1) <NUM> that allows the front card body (FCB) <NUM> to perform as a coupling frame (CF). The module antenna on the transponder chip module (TCM) <NUM> may have suitable overlap with the front card body (FCB) <NUM> to allow optimum performance of the device when operating in contactless communication with an external reader.

An insert <NUM> made of plastic or other suitable non-conductive material may be disposed behind the first module opening (MO1) <NUM> in the front card body (FCB) <NUM> and may be milled or otherwise shaped to accommodate the volume occupied by the chip IC and encapsulation from the transponder chip module (TCM) <NUM>. An insert adhesive <NUM> in film or liquid form may be provided to bond the insert <NUM> to the card. The rear card body (RCB) <NUM> is composed of a metal layer (ML), featuring a second module opening (MO2) <NUM> and a second slit (S2) <NUM>; it behaves as a coupling frame (CF). The rear card body (RCB) <NUM> may have thickness <NUM> to <NUM>. The insert <NUM> may be composed of multiple parts and may contain a tuning circuit with antenna windings and/or capacitors to influence the resonant characteristics of the smartcard.

<FIG> shows the outer face of the rear card body (RCB) <NUM> panel. The second slit (S2) <NUM> is shown in this example as commencing from an internal edge of the panel with respect to the overall perimeter of the assembled card. It is noted that a small gap is provided between the internal edges of the rear card body (RCB) <NUM> and the front card body (FCB) <NUM> in order to prevent electrical short circuiting of the second slit (S2) <NUM>, this gap may be of the order of <NUM> to <NUM>. The rear card body (RCB) <NUM> also features two recesses that may be formed by any appropriate technique including laser ablation, chemical etching or milling. One recess may be used to accommodate a magnetic stripe, i.e. the magnetic stripe recess (MSR) <NUM>. A second recess for a signature panel, i.e. signature panel recess (SPR) <NUM>, may also be provided. These recesses may enable these features to sit flush with the card surface. The recesses may be, alternatively, simply textured regions to assist alignment and adhesion of the appropriate features.

Either one or both of the front card body (FCB) <NUM> and the rear card body (<NUM>) may be coated in a dielectric material. For example, the coating may be a hard wearing decorative black diamond-like-carbon (DLC) with characteristics of very high electrical resistivity. This may be achieved by control of the ratio of conductive carbon (e.g. graphitic sp<NUM> hybridised and amorphous carbon) to insulating carbon (e.g. diamond type sp<NUM> hybridised carbon). Alternative coatings may be considered and may be transparent or other colour, this also includes the use of paints and lacquers or layers of coatings to achieve a desired finish. The coating(s) may be applied to any or all of the surfaces or edges of either of the front card body (FCB) <NUM> or rear card body (RCB) <NUM> in order to provide the necessary electrical isolation between the two panels and enable each to perform as a coupling frame (CF). The use of a dielectric or high resistivity coating in this manner enables the slit (S2) <NUM> to commence from an internal part of the overall card structure and extend towards the second module opening (MO2) <NUM>. This is significant as this configuration can allow strengthening of the assembled card by offsetting the positions of the two slits (S1, <NUM>; S2, <NUM>), in this particular example allowing them to run perpendicular to one another, thereby stabilising the card in the region of the module openings (MO1, <NUM>; MO2, <NUM>).

Either one or both of the front card body (FCB) <NUM> and the rear card body (RCB) <NUM> may be electrically connected, across their respective slits (S1, S2) or other locations to a device or circuit assembly in order to power a circuit or to improve the read/write performance of the smartcard with respect to a reader antenna. The additional circuit or device may be housed in a layer independent of the FCB and RCB and may, for example, reside between them, interacting with the induced eddy currents in each of the coupling frames (CF1, CF2).

The slits (S1, <NUM>; S2, <NUM>) may be made discrete and less visible by cutting them to a narrow width (e.g. <NUM>, <NUM>, <NUM> to <NUM>), this may be achieved by laser cutting for example. In addition the apparent width of the slits (S1, <NUM>; S2, <NUM>) may be reduced by the thickness of coating applied to front or rear card bodies (FCB <NUM>, RCB <NUM>). For example for a diamond-like-carbon (DLC) coating each edge of the slits (S1, <NUM>; S2, <NUM>) may have a coating thickness of <NUM> microns thereby reducing the apparent slit width by <NUM> microns. Alternative coating types or use of multiple coating layers may allow a greater reduction in apparent slit width.

Attention is directed to <CIT>, particularly FIG. 16A thereof, which describes a smartcard having multiple metal layers with slits, the slits in the various layers being oriented differently than one another.

<FIG> illustrates an exploded view of a similar construction to that shown in <FIG> with similar layout of transponder chip module (TCM) <NUM>, front card body (FCB) <NUM>, first slit (S1) <NUM>, module opening (MO) <NUM> and adhesive film (AF) <NUM>. The design does not necessarily feature an insert at the module position. The rear card body (RCB) <NUM> comprises a second slit (S2) <NUM> and accommodates the magnetic stripe (MS) <NUM> and signature panel (SP) <NUM>.

<FIG> shows the outer face of the rear card body (RCB) <NUM>. The panel shown features a magnetic strip recess (MSR) <NUM> and a signature panel recess (SPR) <NUM>. The rear card body does (RCB) <NUM> not feature a module opening (MO) as described previously. Instead, the design features an extended slit (S2) <NUM> which runs inwards from an edge of the rear card body (RCB) <NUM> panel that is internal to the metal smart card and describes a loop around an area overlapping the module antenna (MA) of the transponder chip module (TCM) <NUM>.

The second slit (S2) <NUM> is formed, such as as-shown, to leave an area of solid metal behind the transponder chip module (TCM) <NUM> instead of a module opening (MO). The second slit (S2) <NUM> in this manner enables the rear card body (RCB) <NUM> to function as a coupling frame (CF) by directing induced eddy currents around the module antenna (MA) and permitting inductive coupling. In addition, the design of the second slit (S2) <NUM> in this manner eliminates the need for an insert or other fill material to cover a module opening (MO) and prevents the occurrence of a potential weak spot in the card body behind the transponder chip module (TCM) <NUM>.

The slit (S2) <NUM> may describe any shape, including spiral, in order to optimise the overlap of the coupling frame with a given module antenna (MA). The slit (S2) <NUM> may have varying width along its length, e.g. it may begin at the edge of the panel at a width of <NUM> and widen when in proximity to the module antenna (MA) to <NUM> in order to increase the radio frequency communication performance of the device. The slits (S1, <NUM>; S2, <NUM>) may be filled with resin or other material to prevent ingress of liquid or debris during use of the card. The slit (S2) <NUM> may also be concealed by placement of a security hologram, logo or other feature.

<FIG> shows an exploded view of a variation of a solid metal dual interface card. In this case the first slit (S1) <NUM> of the front card body (FCB) <NUM> runs parallel to the second slit (S2) <NUM> of the rear card body (RCB) <NUM> but is off-set in position such that the slits do not overlap, thereby increasing the mechanical stability of the card near the position of the transponder chip module (TCM) <NUM>. The configuration shown may apply equally to a rear card body (RCB) <NUM> panel that includes a module opening (MO) and second slit (S2).

<FIG> shows a rear view of the assembled solid metal dual interface card, excluding the magnetic stripe (MS) <NUM> and signature panel (SP) <NUM>. The offsetting of the positions of the slits (S1) <NUM> and (S2) <NUM> is shown, such that the slits do not overlap. The rear card body (RCB) <NUM> fits into a pocket milled, etched, stamped or otherwise formed in the rear side of the front card body (FCB) <NUM>. The pocket may allow the rear card body (RCB) <NUM> to be wrapped around its perimeter by a frame from the front card body (FCB) <NUM>. This frame may serve a role in stabilising the front card body (FCB) <NUM> during production of the pocket. For example, if the pocket is formed by a milling tool stress on the metal layer (ML) comprising the front card body (FCB) <NUM> may cause permanent warping. The presence of the frame as shown in <FIG> may add rigidity and stability to the front card body (FCB) <NUM> and to the overall card assembly.

In order to assist milling of the pocket, particularly in the case where the size of the rear card body (RCB) <NUM> occupies a significant portion (e.g. ><NUM> %) of the area of the card, an easily machined metal or metal alloy may be chosen for some or all of the card construction. This could include various alloys of stainless steel or aluminium alloys such as duralumin.

An additional benefit to using a metal alloy relates to the reading and writing of data to the high coercivity magnetic stripe (MS) <NUM>. Placing the magnetic stripe on top of a nonmagnetic metal or metal alloy (e.g. <NUM> series stainless steel, aluminium, aluminium alloys, titanium) results in reduced data corruption and problems reading data using conventional magnetic stripe readers.

Claim 1:
A metal smartcard comprising:
a front card body (FCB, <NUM>, <NUM>) composed of a first metal layer (ML) with a first slit (S1, <NUM>, <NUM>) extending from an outer edge thereof to a module opening (MO, <NUM>, <NUM>) for accepting a transponder chip module (TCM, <NUM>, <NUM>), the first metal layer functioning as a first coupling frame; and
a rear card body (RCB, <NUM>, <NUM>) composed of a second metal layer (ML) with a second slit (S2, <NUM>, <NUM>) extending from an outer edge thereof, the second metal layer functioning as a second coupling frame;
wherein the two metal layers mechanically support one another, in particular around the two slits and the module opening;
the second slit being an extended slit running inwards from an edge of the rear card body that is internal to the metal smart card and describing a loop around an area overlapping a module antenna of the transponder chip module, the second slit further being formed so as to leave an area of solid metal behind the transponder chip module;
further comprising a recess in the first metal layer to accommodate the second metal layer.