Chip card with optimized coupled antenna and method for manufacturing same

Abstract

The present invention relates to a contactless or contact-contactless chip card, comprising a chip card body 5 and an antenna insert 21 arranged between the outer layers 2 of the chip card body 5, the antenna insert 21 comprising a substrate and, on at least one side of the substrate, a coil of a concentrator 3, 4 intended to be electromagnetically coupled to a coil of an antenna 14 of an electronic module 9 arranged in a cavity 6 of the card body 5, the electronic module being characterized in that the concentrator 3, 4 comprises at least one inner coil 3a, 4a which emerges into the cavity 6 and is in the chip card body 5 flush with an internal side wall 17 of the cavity 6.

Description

[Technical Field]

[0001] The present invention relates to an antenna of the type used for contactless chip cards or mixed contact and contactless chip cards, or other security documents in which such an antenna may be used. [Background technology]

[0002] Known antennas for such chip cards are generally incorporated into a multi-layer antenna insert that comprises a substrate typically made from plastic, often polyethylene terephthalate (PET), with the antenna trace formed by an etched layer of aluminum along with a stack of multiple thin layers also made from plastic.

[0003] The antenna is generally configured in the form of two sets of coils, forming a first antenna, called the ID1 antenna, of large size, similar to that of a chip card, intended to be electromagnetically coupled to an external reader, and a second antenna, called the concentrator antenna (more simply known as the concentrator), intended to be electromagnetically coupled to the antenna of the electronic module and electrically connected in series or parallel to the ID1 antenna.

[0004] A network of adjustable capacitors incorporated in both the ID1 antenna and the concentrator antenna allows the entire antenna system to resonate at a given operating frequency, and the antenna system is therefore taken to mean the ID1 antenna, the concentrator antenna and the adjustable capacitors that allow adjusting the resonant frequency of the antenna insert.

[0005] The above-mentioned antenna system is electromagnetically coupled to an electronic module, which is also provided with an antenna arranged around the electronic module, called the module antenna, whether it is, for example, an electronic module of a contactless chip card or an electronic passport. The module antenna is limited in terms of the number of coils by the small size of the electronic module, which must accommodate a microelectronic chip and optionally galvanic contacts in accordance with ISO 7816-2, for example for so-called dual cards for mixed contact and contactless operation.

[0006] In a known embodiment of the antenna insert, the ID1 antenna and concentrator are formed by very narrow etched aluminum traces arranged on a PET substrate, and the adjustable capacitor is formed by metal pads located on both sides of the booster antenna substrate. The coils of the ID1 antenna and the concentrator antenna can be formed on one or both sides of the insert. To close the electrical circuit, crimps, i.e., electrical connections formed by pressing or stamping, are usually used to connect the metal pads located on both sides of the antenna insert substrate. In this known embodiment, the antenna metal traces typically have a thickness of about 10 to 30 micrometers, and the dielectric substrate has a thickness of about 25 to 38 micrometers, which allows obtaining radio frequency operating performance in accordance with current standards (ISO 14443 and ISO 10373-6).

[0007] EP 3543913A1 discloses a chip card provided in an antenna insert for a contactless chip card or a mixed contact / contactless chip card, which is intended to be sandwiched between the outer layers of the chip card body. The antenna insert comprises a substrate and, on at least one side of the substrate, a concentrator coil intended to be electromagnetically coupled to the coil of the antenna of an electronic module located in a cavity in the card body. However, the inner coil of the concentrator is offset with respect to the antenna of the module, which has a negative effect on the quality of the coupling between the two antennas.

[0008] The present invention will be described in general terms with reference to contactless chip card or dual chip card components, and it will be understood that this may be substituted with other products of different formats such as, but not limited to, electronic passports.

[0009] The electronic module of the chip card is inserted into a cavity made in the card body by machining in a known manner, in particular by means of a milling cutter, said cavity comprising two areas of different depths: an area called P2, corresponding to a greater machining depth and containing a sealing drop protecting the module's microelectronic chip, and an area called P1, corresponding to a shallower machining depth and defining the area on which the peripheral antenna of the electronic module rests.

[0010] The cavity of the module is machined when all of the layers of the chip card are assembled, and the antenna insert is held between the outer layers of the card body. For a standard thickness module, i.e., a module having a thickness of about 500 micrometers, the machining in region P2 generally penetrates the antenna insert, which is located at a depth of approximately 400 micrometers, while the shallower machining depth of region P1 does not reach the depth of the antenna insert.

[0011] To maintain the functionality of the coil of ID1 and the concentrator antenna of the insert, there must not be any traces located in the machined area P2. However, to ensure good electromagnetic coupling between the concentrator antenna of the insert and the antenna of the electronic module, the concentrator coil must also be as close as possible to the coil of the antenna of the electronic module.

[0012] Coupling is defined by the geometric similarity between the two antennas and by the distance between them. Therefore, the greater the distance separating the concentrator antenna and the module antenna to define the interaction, the less good the coupling will be, negatively impacting performance. Therefore, the first inner coil of the concentrator is the most critical, and to maximize this performance, it must be as close as possible to the trace coil of the module antenna, and have as many coils as possible in the smallest possible footprint.

[0013] These two simultaneous conditions are already difficult to achieve for modules of standard thickness due to the positioning tolerance of the antenna insert during assembly of the chip card layers, which is approximately 1-2 mm. They become even more difficult when the modules used are so-called "thick" modules, i.e., modules in which both areas P1 and P2 require deep cavities, both of which require machining through the antenna insert layers. This is typically the case for modules known as dCVV, i.e., dynamic card verification value, modules, in which the depths of both areas P1 and P2 are greater than 500 micrometers. In this scenario, the coil of the concentrator antenna cannot be positioned close enough to the coil of the electronic module, resulting in poor radio frequency communication performance of known chip cards equipped with such modules. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] EP3543913A1 Summary of the Invention [Problem to be solved by the invention]

[0015] It is therefore a general object of the present invention to propose an improved antenna insert arrangement, in particular for the body of a contactless chip card or for an electronic passport, which does not have the above-mentioned drawbacks.

[0016] Another more specific object of the invention is to propose an antenna insert structure for contactless chip cards or the like, which ensures optimal coupling with the antenna of the electronic module intended to be integrated into the card body, regardless of the thickness of the module, i.e. in particular whether it is a standard module or a so-called "thick" module, in particular a dCVV module with a thickness of more than 500 micrometers.

[0017] Another object of the invention is to propose a method for manufacturing a chip card that uses the optimized antenna insert according to the invention. [Means for solving the problem]

[0018] According to the principles of the present invention, the solution to the above-mentioned problem consists in making an inner concentrator coil on the antenna insert, which emerges directly into the cavity on its side walls and is wider than the others, and in any case wide enough to compensate for positioning tolerances of the antenna insert between the other layers of the card body during assembly of the antenna insert with the other layers of the chip card.

[0019] To form this wider inner coil, a concentrator blank is manufactured that is provided with a substantially solid central metal area, then the insert provided with this blank is placed between the other layers of the card body, and finally the cavity of the card body and the substantially solid central metal area of the antenna insert are machined, so that after machining, an inner concentrator coil remains on the antenna insert that emerges directly into the cavity and is flush with the side walls of the cavity. The wider inner coil that remains after machining of the module cavity therefore makes it possible both to accommodate positioning tolerances of the antenna insert within the card body and to position this inner coil of the concentrator as close as possible to the coil of the antenna of the electronic module, as can be seen in the figure.

[0020] This method and this concentrator antenna configuration can be advantageously used regardless of which of the regions P1 and P2 of the module is penetrated by the antenna insert, i.e. whether it is a standard module or a thick module.

[0021] The present invention therefore relates to an antenna insert for a contactless chip card or a mixed contact-contactless chip card intended to be sandwiched between the outer layers of a chip card body, said antenna insert comprising a substrate and, on at least one face of said substrate, a coil of a concentrator intended to be electromagnetically coupled to the coil of an antenna of an electronic module placed in a cavity of the card body, said concentrator comprising at least one inner coil which emerges into the cavity and is flush with the internal side wall of said cavity of the chip card body.

[0022] According to one preferred embodiment, said inner coil of the concentrator is wider than the other coils of the concentrator.

[0023] According to one advantageous embodiment, the width of the inner coil of the concentrator is greater than the value of the positioning tolerance of the antenna insert between the outer layers of the chip card body, which makes it possible to compensate for the lateral positioning tolerance of the insert between the layers of the chip card body and prevents the inner coil of the concentrator from being cut off during machining of the cavity.

[0024] According to one embodiment, the width of the inner coil is greater than approximately 2.2 mm when the positioning tolerance of the antenna insert within the card body is less than 2 mm.

[0025] According to one embodiment, the concentrator is a single-sided antenna, with all of its coils located on one side of the substrate of the insert, and with a single inner coil emerging into the cavity.

[0026] According to one variant embodiment, the concentrator is a double-sided antenna, the coils of which are distributed between two opposite faces of the substrate of the antenna insert and connected in series or parallel using vias or crimps, said concentrator comprising two inner coils emerging into cavities on either side of the substrate.

[0027] The present invention also relates to a method for manufacturing a chip card equipped with an antenna insert as defined above, - forming an antenna insert blank having a substrate bearing a plurality of etched aluminum coils and a solid unetched core on at least one side of the substrate; - placing the antenna insert blank between outer layers and laminating them together to form a card body; - machining one face of the card body to form therein a cavity intended to receive an electronic module, said cavity passing through said solid center of the antenna insert blank and said substrate, so that after machining of the cavity, said center leaves an inner concentrator coil flush with the inner sidewall of the cavity; - depositing a layer of adhesive around the periphery of the module; - transferring and fixing an electronic module into said cavity, around which traces of a module antenna are provided, so that said antenna traces of the module are adjacent to or face said inner traces of the concentrator; The present invention is characterized by comprising:

[0028] Further features and advantages of the present invention will become apparent upon reading the detailed description and upon reference to the accompanying drawings. [Brief explanation of the drawings]

[0029] [Figure 1A] 1 shows a cross section of a known chip card during the steps of machining a cavity and inserting a module of standard thickness; [Figure 1B] 1 shows a cross section of a known chip card during the steps of machining a cavity and inserting a module of standard thickness; [Figure 1C] 1 shows a cross section of a known chip card during the steps of machining a cavity and inserting a module of standard thickness; [Figure 1D] 1 shows a cross section of a known chip card during the steps of machining a cavity and inserting a module of standard thickness; [Figure 1E] 1A-1D show top views of the relative placement of the coils of the single-sided concentrator and the coils of the antenna of the module. [Figure 2A] 1 shows a cross-section of a known chip card during the steps of machining a cavity and inserting a thick dCVV module; [Figure 2B] 1 shows a cross-section of a known chip card during the steps of machining a cavity and inserting a thick dCVV module; [Figure 2C] 1 shows a cross-section of a known chip card during the steps of machining a cavity and inserting a thick dCVV module; [Figure 2D] 2A-2C show top views of the relative placement of the coils of the concentrator and the coils of the antenna of the module; [Figure 3A] 2 shows different views of a chip card according to the invention during the steps of machining a cavity and inserting a thick electronic module into the cavity; [Figure 3B] 2 shows different views of a chip card according to the invention during the steps of machining a cavity and inserting a thick electronic module into the cavity; [Figure 3C] 2 shows different views of a chip card according to the invention during the steps of machining a cavity and inserting a thick electronic module into the cavity; [Figure 3D] 2 shows different views of a chip card according to the invention during the steps of machining a cavity and inserting a thick electronic module into the cavity; [Figure 3E] 3A-3D show top views of the relative placement of the coils of the concentrator and the coils of the antenna of the module. [Figure 4A] 1 shows different views of a chip card according to the invention with a single-sided antenna insert during the steps of machining the cavity and inserting a module of standard thickness; [Figure 4B] 1 shows different views of a chip card according to the invention with a single-sided antenna insert during the steps of machining the cavity and inserting a module of standard thickness; [Figure 4C] 1 shows different views of a chip card according to the invention with a single-sided antenna insert during the steps of machining the cavity and inserting a module of standard thickness; [Figure 4D]1 shows different views of a chip card according to the invention with a single-sided antenna insert during the steps of machining the cavity and inserting a module of standard thickness; [Figure 4E] 4A-4D show top views of the relative placement of the coils of the concentrator and the coils of the antenna of the module. [Figure 5A] 1 shows different views of a chip card according to the invention with double-sided concentrator antenna inserts during the steps of machining the cavity and inserting the thick module; [Figure 5B] 1 shows different views of a chip card according to the invention with double-sided concentrator antenna inserts during the steps of machining the cavity and inserting the thick module; [Figure 5C] 1 shows different views of a chip card according to the invention with double-sided concentrator antenna inserts during the steps of machining the cavity and inserting the thick module; [Figure 5D] 1 shows different views of a chip card according to the invention with double-sided concentrator antenna inserts during the steps of machining the cavity and inserting the thick module; [Figure 5E] 5A-5D show top views of the relative placement of the coils of the concentrator and the coils of the antenna of the module. DETAILED DESCRIPTION OF THE INVENTION

[0030] Reference is made to FIG. 1, which illustrates the steps for manufacturing a dual-chip card provided with an antenna insert 1 according to the prior art. This antenna insert is provided with a coil 3 forming a concentrator, and another coil shown forms part of another component of the insert, for example the ID1 antenna. This antenna insert 1 is first laminated between outer layers 2 to obtain a card body 5 (FIG. 1A). After lamination of the card body, a cavity 6 is machined in this card body 5 using a milling cutter 7 (FIG. 1B). The milling cutter 7 machines one cavity portion to a depth P2 and another, wider cavity portion to a depth P1. As the depth P2 is deeper than half the thickness of the card body 5, this machining penetrates the antenna insert 1, which means that the inner coil 3a of the concentrator 3 has to be located at a certain distance 15 from the inner side wall of the cavity machined to the depth P2 (FIG. 1D), so that the machining of the area P2 does not damage the concentrator 3, in particular its inner coil 3a, during said machining.

[0031] Once the cavity 6 has been machined, the chip card electronic module 9 is inserted into the cavity 6 (FIGS. 1C and 1D). As is known, the module comprises a substrate 10 on which contacts, particularly in ISO 7816-2 format, are formed, and a microelectronic chip 11, protected by a drop of encapsulating resin 12, is fixed underneath the substrate 10. The electronic module 9 is fixed in the cavity 6 by means of a layer of adhesive 13, which is placed between the antenna 14 of the electronic module 9 and the bottom of the cavity 6 at a depth P1 (FIGS. 1C and 1D). As can be seen more clearly in the enlarged view 1D of FIG. 1C, the lateral positioning tolerance of the antenna insert 1 requires that a certain distance 15 be maintained between the coil 3a of the concentrator 3 and the inner side wall 17 of the cavity 6 during machining of the cavity 6 in order to avoid the risk of cutting the inner coil 3a of the concentrator. This distance 15 causes an offset between the coil of the concentrator 3 and the coil of the antenna 14 of the module, which has a negative effect on the good coupling coefficient between the antenna 14 of the electronic module and the concentrator 3. The arrangement of the coil of the concentrator 3, in particular its inner coil 3a, is shown in solid lines in Figure 1E, which is a top view (ISO contacts of the module not shown), and the coil of the antenna 14 of the electronic module is shown in dashed lines.

[0032] The problem of causing offset 15 persists when the standard electronic module used in FIG. 1 is replaced with a thicker module that requires a cavity, and as shown in FIG. 2, particularly in FIGS. 2C and 2D, both cavity depths P1 and P2 are at a position that exceeds the depth at which the antenna insert 1 is located.

[0033] To overcome this problem, the present invention proposes a structure and method as shown diagrammatically in FIG. 3. As shown in FIG. 3A, an antenna insert blank 21a is used, which is provided around its periphery with a concentrator formed by its coil 3 in a known manner. The center of the concentrator is initially formed by a substantially solid metal core 16. The right-hand portion of FIG. 3A shows a simplified top view of the area of the concentrator 3, with hatching corresponding to the future position of the module 9. Once the antenna insert blank 21a is laminated between the outer layers 2 of the card body, the cavity 6 of the card body is machined as diagrammatically shown in FIG. 3B, removing the solid center 16 of the antenna insert blank 21a and leaving the inner concentrator coil 3a along the cavity 6, which emerges directly within the cavity 6 and is flush with the inner sidewall 17 of the cavity 6. Thus, an antenna insert 21 according to the present invention is obtained, embedded between the outer layers 2 of the card body 5. The electronic module 9 provided with the antenna 14 is then inserted into the cavity in a known manner. As can be seen in FIG. 3D, an enlarged view of FIG. 3C, and in the top view in FIG. 3E, there is very little distance between the outer coil of the module's antenna 14 and the inner coil 3a of the antenna insert 21 (besides the very small gap that allows the module 9 to be inserted into the cavity 6). Here, these two coils 3a and 14 are actually continuous, merely positioned at potentially different depths. In any case, for a given thickness of electronic module 9, these two coils are much closer than in the configurations of FIGS. 1 and 2, since the distance 15 (FIG. 1D) due to the lateral positioning tolerance of the insert within the card body is eliminated. The increased proximity between the coil of the concentrator 3 and the coil of the antenna 14 of the electronic module 9 makes it possible to achieve improved coupling between the antenna of the electronic module and the antenna of the antenna insert. Furthermore, the distance between the inner coil 3a of the concentrator 3 and the outer coil of the module's antenna 14 is constant here for a given module type.

[0034] 4A-4D are similar to FIGS. 3A-3D, except that the electronic module 9 used is a standard thickness module, so that region P1 of cavity 6 does not penetrate antenna insert 21. As can be seen in FIG. 4B, in this scenario, only machining to depth P2 penetrates antenna insert 21. As a result, inner coil 3a of the concentrator is now directly opposite the coil of antenna 14 of the electronic module, which produces optimal coupling (FIG. 4D).

[0035] FIG. 5 is similar to FIG. 3, except that the antenna insert 21 now includes a double-sided concentrator, whose coils 3 and 4 are distributed on both sides of the insert's substrate. In this case, a concentrator blank 21a is first used, provided with two substantially solid metal centers 16, one on each side of the substrate. When a thick electronic module is used, a cavity 6 is machined in this case (FIG. 5B), and within the cavity 6, two regions P1 and P2 are drilled through the insert blank, thereby removing the solid metal center regions on both sides of the concentrator blank (FIG. 5D), leaving only the inner walls 17 of the cavity's inner coils 3a and 4a emerging within the cavity 6. This again minimizes the distance between these inner coils 3a and 4a of the double-sided concentrators 3 and 4 and the coils of the electronic module's antenna 14, thus improving the coupling between the double-sided concentrator and the module's antenna 14. [Industrial Applicability]

[0036] Ultimately, the invention makes it possible to achieve the stated objective, in particular with regard to the communication performance of a chip card equipped with an antenna insert according to the invention, by bringing the inner coil of the concentrator closer to the coil of the antenna of the module, thereby making it possible to eliminate the negative effects of positioning tolerances of the antenna insert, and consequently leading to an increase in the coupling coefficient between these two antennas.

[0037] Furthermore, here the distance between the inner coil 3a of the concentrator 3 and the outer coil of the antenna 14 of the module is constant for a given type of module.

[0038] The novel structure does not require a significant change in the method for assembling the antenna insert within the card body. Only the method for manufacturing the insert is changed by using a concentrator blank having a substantially solid metal center prior to the machining step that removes this substantially solid metal center and completes the geometry of the concentrator and antenna insert.

[0039] This method and this concentrator antenna configuration can be used to advantage no matter which region P1, P2 of the module is penetrated by the antenna insert and what the machining depth of the cavity in the module is.

Claims

1. A non-contact or contact-non-contact hybrid chip card comprising a chip card body (5) and an antenna insert (21) sandwiched between the outer layer (2) of the chip card body (5), wherein the antenna insert (21) comprises a substrate and the coils of concentrators (3, 4) on at least one surface of the substrate, which are intended to be electromagnetically coupled to the coils of an antenna (14) of an electronic module (9) disposed in a cavity (6) of the card body (5), wherein the concentrators (3, 4) comprise at least one inner coil (3a, 4a), the at least one inner coil (3a, 4a) appearing in the cavity (6) and being coplanar with the inner side wall (17) of the cavity (6) of the chip card body (5).

2. The chip card according to claim 1, characterized in that the inner coils (3a, 4a) of the concentrators (3, 4) of the antenna insert (21) are wider than the other coils of the concentrators.

3. The chip card according to claim 2, characterized in that the width of the inner coils (3a, 4a) of the concentrators (3, 4) is greater than the value of the positioning tolerance of the antenna insert (21) between the outer layers (2) of the chip card body (5).

4. The chip card according to claim 3, characterized in that when the positioning tolerance of the antenna insert (21) in the card body (5) is less than 2 mm, the width of the inner coils (3a, 4a) is greater than 2.2 mm.

5. The chip card according to any one of claims 1 to 4, characterized in that the concentrator (3) is a single-sided antenna, and all of the coils of the concentrator (3) are arranged on one side of the substrate of the insert (21) and comprise a single inner coil (3a) that appears in the cavity (6) of the card body (5).

6. A chip card according to any one of claims 1 to 4, characterized in that the concentrator of the insert (21) is a double-sided antenna, the coils (3, 4) of the concentrator are distributed between the two opposing surfaces of the substrate of the antenna insert (21) and connected in series or parallel using vias, crimps or capacitors, and the concentrator comprises two inner coils (3a, 4a) that appear in the cavity (6) of the card body (5).

7. An antenna insert (21) for a chip card, comprising a substrate (1) and the coils of concentrators (3, 4) intended to be electromagnetically coupled to the coils of an antenna (14) of an electronic module (9) disposed in a cavity (6) of a card body (5), wherein the concentrators (3, 4) comprise at least one inner coil (3a, 4a), the at least one inner coil (3a, 4a) appears in the cavity (6) of the card body (5) and is coplanar with the inner side wall (17) of the cavity (6) of the chip card body (5), according to any one of claims 1 to 4.

8. A method for manufacturing a chip card, - The steps include forming an antenna insert blank (21a) comprising a substrate (21) having a plurality of etched aluminum antenna coils (3, 4) and an unetched substantially solid center (16), - The steps include placing the antenna insert blank (21a) with the antennas (3, 4) provided between the outer layers (2), and stacking them together to form the card body (5), - The steps of machining one surface of the card body (5) to form a cavity (6) inside it, which is intended to receive an electronic module (9), the cavity (6) passing through the solid center (16) of the antenna insert blank (21a), and as a result, after machining the cavity (6), the center (16) forms an inner concentrator coil (3a, 4a) which is coplanar with the inner side wall (17) of the cavity (6), - A step of depositing an adhesive layer (13) around the electronic module (9), - The electronic module (9) is moved and fixed into the cavity (6), and traces of the module antenna (14) are provided around the electronic module (9), so that the antenna traces of the module are adjacent to the inner traces (3a, 4a) of the concentrators (3, 4), or face the inner coils (3a, 4a) of the concentrators, A method for manufacturing a chip card according to any one of claims 1 to 4, characterized by including the following:

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