Metal-containing dual interface smartcards
View Patent ↗Smartcard (SC) having a metal card body (MCB) which is a coupling frame (CF) with a slit (S), and a coupling loop antenna/structure (CLA, CLS) connected to termination points (TP) on each side of the slit (S) and coupled with the module antenna (MA) of a transponder chip module (TCM). A portion of the card body (CB) may be metal and another, coplanar portion of the card body may be a synthetic material which may be transparent or translucent. Currents may be collected from the interface between the two portions. The card body (CB) may have two metal layers of different materials, adhesively joined to each other using a thermosetting epoxy that converts from B-stage to C-stage during lamination.
1. A smartcard comprising:
a card body including at least one metal layer; and
a flexible circuit separate from the card body and including two coils interconnected with each other by at least one conductor,
wherein the flexible circuit includes at least one of flexible tape, an FR4 film, or a Kapton film.
2. The smartcard of claim 1 , wherein:
the card body includes a first slit in the at least one metal layer, wherein the first slit extends to a periphery of the at least one metal layer; and
a first coil of the two coils overlaps the first slit.
3. The smartcard of claim 2 , wherein:
the card body includes a second slit in the at least one metal layer, wherein the second slit extends to a periphery of the at least one metal layer; and
a second coil of the two coils overlaps the second slit.
4. The smartcard of claim 1 , wherein the flexible circuit includes a capacitor.
5. The smartcard of claim 1 , wherein a first coil of the two coils is configured to inductively couple with a module antenna to communicate with an integrated circuit.
6. The smartcard of claim 5 , wherein a second coil of the two coils is not configured to inductively couple with the module antenna.
7. The smartcard of claim 1 , wherein a second coil of the two coils is configured to pick up surface currents around a slit in the at least one metal layer extending to an outer edge of the at least one metal layer.
8. The smartcard of claim 1 , wherein the at least one metal layer includes a first metal layer and a second metal layer, and wherein the flexible circuit is interposed between the first metal layer and the second metal layer.
9. The smartcard of claim 1 , wherein the flexible circuit includes flexible tape.
10. A smartcard, comprising:
a first metal layer including an aperture and a first slit extending through a thickness of the first metal layer and extending from the aperture to an outer edge of the first metal layer;
a transponder chip module including an integrated circuit and a module antenna, wherein the transponder chip module is received by the first metal layer; and
a flexible circuit separate from the first metal layer and including a first coil, at least one conductor connected to the first coil, and at least one of a flexible tape, an FR4material, or a Kapton material,
wherein the first coil overlaps the first slit.
11. The smartcard of claim 10 , wherein the first metal layer includes a second slit through the thickness of the first metal layer and to an outer edge of the first metal layer.
12. The smartcard of claim 11 , wherein the second slit does not extend to the aperture of the first metal layer.
13. The smartcard of claim 10 , wherein the flexible circuit includes a second coil connected to the at least one conductor, wherein the second coil overlaps the second slit.
14. The smartcard of claim 10 , further comprising a second metal layer, wherein the flexible circuit is interposed between the first metal layer and the second metal layer.
15. A smartcard, comprising:
a first metal layer having an aperture and a first slit extending through a thickness of the first metal layer and extending from the aperture of the first metal layer to an outer edge of the first metal layer;
a second metal layer having an aperture and a first slit extending through a thickness of the second metal layer and extending from the aperture of the second metal layer to an outer edge of the second metal layer;
a transponder chip module including a chip and a module antenna, received by the aperture of the first metal layer and the aperture of the second metal layer; and
a flexible circuit including a sense coil portion and an elongate portion extending from the sense coil portion,
wherein the sense coil portion includes a sense coil configured to couple with the module antenna of the transponder chip module.
16. The smartcard of claim 15 , wherein:
the first metal layer further comprises a second slit extending through the thickness of the first metal layer and extending to the outer edge of the first metal layer;
the second metal layer further comprises a second slit extending through the thickness of the second metal layer and extending to the outer edge of the second metal layer; and
the flexible circuit is configured to direct current to the sense coil from a region apart from the sense coil.
17. The smartcard of claim 16 , wherein a region in the flexible circuit distal from the sense coil and across at least a portion of the elongate portion includes a second sense coil overlapping the second slit of the first metal layer and the second slit of the second metal layer.
18. The smartcard of claim 16 , wherein a region in the flexible circuit distal from the sense coil and across at last a portion of the elongated portion includes a plurality of termination points.
19. The smartcard of claim 15 , wherein the flexible circuit includes flexible tape.
20. The smartcard of claim 15 , wherein the flexible circuit further includes a capacitor.