Method for manufacturing a wire antenna for a smart card, and the antenna thus obtained

Abstract

The invention relates to a smart card antenna comprising at least one loop formed on a substrate (1) of generally rectangular shape having two long sides (A) and two short sides (B), said antenna (2) having two antenna ends (3), each having a contact area (6) intended to be connected to a terminal of a contactless communication interface of a microelectronic module for a smart card, characterized in that each antenna end (3) has at least one element substantially parallel to the long sides (A) of the rectangular substrate (1). Figure 3B for the abstract

Description

Title of the invention: Method for manufacturing a wire antenna for a smart card, and antenna thus obtained

[0001] The present invention relates to the field of electronic documents such as smart cards equipped with an antenna enabling them to communicate without contact with a remote reader.

[0002] These may be smart cards that operate only in contactless mode, or so-called dual or hybrid smart cards, capable of communicating with a reader in both contactless and contact modes. These smart cards, as is well known, comprise a plastic body with a cavity in which an electronic module is fixed. In the case of hybrid smart cards, the electronic module comprises a chip with, on the one hand, a communication interface connected to contacts of the module accessible on one side of the smart card, and on the other hand, a contactless communication interface connected to the ends of the smart card's antenna, hidden inside the cavity of the card body.

[0003] The antenna is generally positioned on a plastic substrate (or "inlay" in Anglo-Saxon terminology) which is positioned between several plastic layers of the card body which are laminated together.

[0004] The antenna can be made by etching metallic tracks, but a portion of the market is moving towards so-called wire antennas, made by embedding a very thin metallic wire to form antenna loops in the surface of the insert. This process uses a sonotrode that generates ultrasound and embeds the metallic wire in the surface of the insert as it moves.

[0005] Such a method for embedding the antenna of a smart card is described in document W0 2016 / 051065 AL. In order to allow contact between the antenna ends and the corresponding terminals of the contactless communication interface of the electronic module, these ends are aligned along a so-called horizontal line, namely a line parallel to the longer sides of the rectangle in which the smart card is inscribed. Furthermore, in order to optimize the quality of the contact between the antenna ends and the corresponding pads of the contactless interface of the electronic module, these antenna ends have a zigzag or looped shape with strands substantially oriented in a vertical direction, namely a direction parallel to the shorter sides of the smart card, and therefore perpendicular to the horizontal alignment line of the antenna ends on the card body insert. The strands The successive zigzags forming the ends of the antenna are connected by bends or turns.

[0006] This arrangement produces the expected advantages in terms of connection quality compared to antenna ends without zigzag elements. However, it also presents disadvantages related to the manufacturing process of the embedded antenna.

[0007] Indeed, to industrially produce embedded antennas using a sonotrode, a sheet of plastic material intended for the production of several antennas is held fixed on a table that moves relative to the sonotrode in such a way that the relative movement of the sonotrode with respect to the moving table corresponds to the geometry of the wire antenna to be produced. In practice, the table is most often moved in a direction parallel to the longer side of the rectangular antennas, and the sonotrode is most often moved above the sheet of inserts in a direction parallel to the shorter sides of the rectangular inserts.

[0008] The two movements, namely that of the table and that of the sonotrode, are coordinated by the automated controls of the antenna manufacturing machine in such a way that the relative movement of the end of the sonotrode with respect to the antenna sheet follows a trajectory corresponding to the shape of the antenna coils and their ends. The manufacturing efficiency of the antenna coils using the sonotrode is then a function of the speed at which the assembly consisting of the moving table and the sonotrode completes the entire trajectory necessary to produce a complete antenna.

[0009] Experience has shown that, among all the wire antenna sections to be produced, the zigzag ends of the antenna take the longest to manufacture, due to the changes in direction of the sonotrode's movement between two successive strands of the zigzag separated by a bend. Indeed, manufacturing each strand requires an acceleration of the relative movement between the moving table and the sonotrode parallel to the direction of the strand, then a braking before the bend is formed, followed by a slight displacement of the moving table perpendicular to the strands, and finally another acceleration of the relative movement in the opposite direction to manufacture the next strand, and so on for the different strands constituting a zigzag antenna end.

[0010] In the antenna end configuration as described in the aforementioned document, the strands of the zigzag are therefore substantially parallel to the slowest relative movement, namely that which is carried out parallel to the small sides of the insert or smart card, which considerably slows down the antenna manufacturing process.

[0011] Furthermore, some new types of electronic modules for smart cards have their antenna connection pads aligned vertically, i.e., parallel to the short sides of the smart card, and not horizontally as described in the aforementioned document. Consequently, the known method is not well suited to manufacturing antennas for this new type of electronic module. Object of the invention

[0012] The invention therefore aims to remedy the aforementioned problems and to propose an antenna structure for a security document such as a smart card, the ends of which have a zigzag or lace-like shape, and which is easier to produce with a higher manufacturing yield and therefore a lower unit cost.

[0013] Another object of the invention is to propose a smart card antenna structure better suited to modules whose connection pads to the contactless communication interface of the module are aligned in a vertical direction, i.e. parallel to the short sides of the smart card. Object of the invention

[0014] The invention therefore relates to a smart card antenna, comprising at least one loop made on a substrate of generally rectangular shape having two long sides and two short sides, said antenna having two antenna ends each having a contact area intended to be connected to a terminal of a contactless communication interface of a microelectronic module for smart card, characterized in that each antenna end has at least one strand substantially parallel to the long sides of the rectangular-shaped substrate.

[0015] According to one embodiment, each antenna end comprises a plurality of strands substantially parallel to the long sides of the rectangular substrate of the antenna, said strands being arranged in a zigzag and connected in pairs by bends oriented substantially perpendicular to the long sides of the substrate, so that the contact area of ​​each antenna end with the terminals of an electronic module for a smart card is located straddling several contiguous strands.

[0016] According to one embodiment, the contact areas of the two antenna ends are aligned along a line parallel to the short sides of the rectangular-shaped substrate.

[0017] According to one embodiment, said substrate is a layer of insulating plastic material, 86.5 mm long, 54 mm wide, and approximately 800 micrometers thick, to within 50 micrometers.

[0018] The invention also relates to a smart card comprising a card body having a cavity integrating a microelectronic module having an interface of contactless communication with a reader, characterized in that it comprises within its thickness a substrate equipped with an antenna such as described above.

[0019] The invention also relates to a method for manufacturing an antenna as described above, comprising steps of producing, by embedding a metal wire in the surface of a substrate by means of an ultrasonic sonotrode, an antenna comprising turns and two antenna ends in the form of zigzag strands separated by bends, characterized in that for the production of the antenna ends, said substrate and the sonotrode are animated by a relative movement consisting of displacements substantially parallel to a long side of the substrate, corresponding to the production of the zigzag strands, interspersed with displacements substantially parallel to a short side of the antenna, corresponding to the production of the bends between the zigzag strands.

[0020] According to one embodiment of the method, several antennas are made on a substrate sheet fixed on a mobile table in translation parallel to the strands of the ends of the antennas, and the sonotrode is moved perpendicularly to the strands of the ends of the antennas for the making of the bends. Detailed description

[0021] The invention will be described in more detail in connection with the figures, in which: - The [Fig. 1] represents a plan view of an insert for a contactless smart card provided with an antenna whose zigzag ends conform to the prior art represented by the prior art document W0 2016 / 051065 Al cited above; - Figures 2A and 2B are respectively a plan view of a smart card insert provided with a first embodiment of an antenna according to the invention, and an enlarged view of the zigzag ends of this antenna; - Figures 3A and 3B are respectively a plan view of a mode a preferred embodiment of a smart card insert provided with an antenna according to the invention, and an enlarged view of the ends of the antenna according to the invention; - Fig. 4 is a schematic perspective view of a movable table and sonotrode used for manufacturing antennas according to the invention by inlay. - Fig. 5 is an exploded perspective view of a smart card equipped with an antenna according to the invention.

[0022] Reference is made to [Fig. 1] corresponding to a smart card insert 1 provided with an antenna 2 conforming to the prior art. The turns of the antenna 2 are arranged in the upper half of the insert 1, so as not to be damaged by The creation of characters will be carried out by embossing on the lower half of the body of a smart card using the insert. The turns of the antenna 2 terminate in two ends 3 which extend in a vertical direction, parallel to the axis denoted y. These ends 3 are aligned along the horizontal direction denoted X and are accompanied by a set of zigzag strands 4, which also extend substantially along the vertical axis Y, the successive strands being connected by very small bends.

[0023] For the fabrication of this type of antenna, a substrate consisting of a sheet of plastic material large enough to support a large number of antennas arranged in rows and columns is used in a known manner. This sheet is fixed to a movable table that can move along the horizontal direction denoted X, and a sonotrode moves above the sheet along the Y direction to embed a metal wire into the plastic sheet. The combined movement of the table and the sonotrode is calculated to obtain the desired shape of the antenna tracks and their ends.

[0024] As explained above, this configuration is not well suited for the realization of antennas whose ends must be aligned along the vertical Y direction, perpendicular to the long side of the smart card, as required by a number of microelectronic modules.

[0025] In order to remedy this problem, the invention proposes modified antennas, as explained in relation to figures 2 and 3.

[0026] According to an improved embodiment of the antenna 2, shown in Figure 2, the antenna comprises a set of turns and two ends 3 extending parallel to each other and parallel to the direction X corresponding to the long side A of the substrate and the board in which it will be incorporated. Furthermore, the ends 3 are separated by a distance corresponding to the distance between the contact pads of the contactless interface of a microelectronic module whose position is represented by line 5 in the figures.

[0027] This arrangement makes it possible to manufacture antennas 2 and substrates or inserts better suited to the manufacture of contactless smart cards using electronic modules whose output pads of the contactless communication interface are aligned in a vertical direction, denoted Y.

[0028] However, given the positioning tolerances of the ends 3 achieved by the sonotrode, and the positioning tolerances of the electronic module during smart card assembly, this antenna configuration as such is not yet sufficient to ensure optimal manufacturing efficiency. Indeed, due to the tolerances related to the displacement of the sonotrode, the contact areas 6 may not perfectly align with the output pads of the contactless interface of a smart card electronic module, and the antenna thus obtained will not It could then not be used to manufacture a functional contactless smart card.

[0029] The preferred solution is then shown in Figure 3. In this antenna configuration 2, the ends 3 of the antenna 2 are arranged vertically along the Y-axis parallel to the short sides B of the substrate 1 and are formed by zigzag elements 4 arranged along the horizontal X-axis parallel to the long side A of the antenna substrate 1. In other words, the elements 4 of the ends 3 of the antenna 2 extend perpendicularly to the alignment axis Y of the contact pads 6 of the electronic module intended for use with the antenna.

[0030] As schematically illustrated in [Fig. 4], in order to further optimize the manufacturing yield of the antenna according to the invention, the manufacturing process will use a movable table 11 on which is placed a substrate 1 in the form of a plastic sheet 12, on which will be fabricated a plurality of antennas 2 arranged in rows parallel to the X-axis and in columns parallel to the Y-axis. Optimally, the table 11 will be movable in translation along the same X-axis, parallel to the zigzag wires 4 at the ends 3 of the antennas 2. The relative X,Y movement of the sonotrode 14 and the X movement of the table 11 will correspond to the path of the wire used to fabricate each antenna 2.

[0031] When a board 12 of antennas 2 has been completed by the sonotrode 14, these antennas will be individualized by cutting in a known way to form inserts intended to be integrated into contactless smart cards.

[0032] In [Fig. 5] a smart card 10 capable of using an antenna 2 according to the invention is shown. The smart card 10 comprises, in a known manner, an electronic module 7 provided on its underside with a microelectronic chip 5 embedded in a protective resin, and two output pads 8 of the contactless communication interface of the electronic module 7. A cavity 9 in the body of the smart card 10 exposes the contact areas 6 of the ends of the antenna 2 according to the present invention. Advantages of the invention

[0033] The invention achieves the stated objectives. It allows for the production, in a more efficient and lower cost manner, of wire antennas for contactless smart cards or for cards with mixed contact and contactless operation, having optimized ends so as to allow for very rapid inlay of the metal wire to form the antennas more efficiently while using conventional tools such as a sonotrode and a moving platform carrying the sheets intended for the production of the inserts equipped with antennas.

[0034] Furthermore, the new method for manufacturing the antennas is better suited to the use of electronic modules whose connection pads at the interface The module contacts are aligned along a vertical Y direction, parallel to the short sides of the insert or smart card.

Claims

Claims

1. Antenna (2) for a smart card, comprising at least one turn produced on a substrate (1) of generally rectangular shape having two large sides (A) and two small sides (B), said antenna (2) having two antenna ends (3) each comprising a contact zone (6) intended to be connected to a terminal of a contactless communication interface of a microelectronic module for a smart card, each antenna end (3) comprising a plurality of strands (4) substantially parallel to the large sides (A) of the rectangular substrate (1) of the antenna (2), said strands (4) being arranged in a zigzag pattern and connected two by two by bends oriented substantially perpendicular to the large sides (A) of the substrate (1),such that the contact area (6) of each antenna end (3) is located astride several contiguous strands (4) and that the strands (4) of the ends (3) of the antenna (2) extend perpendicular to an alignment axis (Y) of the contact pads (6) of the electronic module parallel to the short sides (B) of the substrate (1) and intended to be used with the antenna (2), characterized in that the contact areas (6) of the two antenna ends (3) are aligned along a line parallel to the short sides (B) of the rectangular substrate (1), and in that said substrate (1) is a layer of insulating plastic material, 86.5 mm long, 54 mm wide, and 800 micrometers thick to within 50 micrometers.,

2. Smart card (10) comprising a card body provided with a cavity integrating a microelectronic module (7) provided with a contactless communication interface with a reader, characterized in that it comprises in its thickness a substrate (1) provided with an antenna (2) according to claim 1.

3. Method for manufacturing at least one antenna (2) according to claim 1, this method comprising steps consisting in producing, by inlaying a metal wire in the surface of a substrate (1) by means of an ultrasonic sonotrode (14), an antenna (2) comprising turns and two antenna ends (3) in the form of zigzag strands (4) separated by bends, characterized in that for producing the ends (3) of the antenna (2), said substrate (1) fixed on a table (11) and the sonotrode (14) are driven by a relative movement consisting of displacements substantially parallel to a large side (A) of the substrate (1), corresponding to the production of the strands (4) of the zigzag, interspersed with displacements substantially parallel to a small side (B) of the antenna (2), corresponding to the production of the elbows, and in that the relative movement along axes (X,Y) of the sonotrode (14) and along an axis (X) of the table (11) corresponds to the path of the metal wire to produce each antenna (2).

4. Manufacturing method according to claim 3, characterized in that several antennas (2) are produced on a substrate sheet (1) fixed on a table movable in translation parallel to the strands (4) of the ends (3) of the antennas (2), and in that the sonotrode (14) is moved perpendicular to the strands (4) of the ends (3) of the antennas to produce the bends.

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