Electrochemical metallization process for double-sided circuits of chip cards and circuit obtained with this process

Abstract

Electrochemical metallization method for double-sided circuits (3) of chip cards. Contact pads (5) and current leads (4) are located on the front side, antennas (8) and connection pads (51, 52) are located on the back side. The method comprises the operation of electrochemically depositing at least one layer of electrically conductive material (60) on the connection pads (51, 52) while providing an electric current to these connection pads (51, 52) through the current leads (4). The contact pads (5) and the metallization holes (40) establish electrical continuity between the front side (6) and the back side (7). The method further comprises the operation of electrically isolating at least one metallization hole (40) from the connection pads (52) after the electrochemical deposition of the at least one layer of electrically conductive material (60). Circuit obtained using the method.

Description

Technical Field

[0001] This invention relates to the field of chip cards, and more particularly to the field of electronic modules for chip cards. Background Technology

[0002] Chip cards have many uses: credit cards, mobile phone SIM cards, transportation cards, ID cards, etc.

[0003] These cards typically consist of a rigid carrier, such as plastic, which forms the main part of the card, into which a separately manufactured electronic module is incorporated. This electronic module includes flexible circuitry with, for example, an electronic chip (integrated circuit) and means for connecting the chip to devices for reading and / or writing data recorded in the chip.

[0004] This invention specifically relates to the field of so-called "dual" cards, meaning cards with dual communication interfaces to the chip. In other words, these cards allow for contact-based or contactless communication and are also known as "Combi" cards.

[0005] For “contact-based” use, the contacts are attached to the chip and exposed on the surface of the module, allowing for electrical connections that enable reading and / or writing to the device when a card is inserted.

[0006] For "contactless" use, there are two types of dual cards.

[0007] In the first type of card, an antenna arranged in the card carrier (also called the card body) is electrically connected to the chip. In this case, the chip is able to exchange data with the read / write device, either by creating a direct electrical connection between the read / write device and the module's contacts, or by creating a direct electromagnetic coupling between the antenna and the read / write device.

[0008] In the second type of card, the first antenna, called the "module antenna," is integrated into the module and allows inductive coupling (and therefore no electrical connection) to the second antenna, referred to as the "enhanced antenna or main antenna," which is integrated into the card's rigid carrier. The first antenna is smaller than the second antenna. The second antenna can cover a larger surface area on the card than the module, allowing for a greater communication range. In this case, the chip is also able to exchange data with the read / write device, either by creating a direct electrical connection between the read / write device and the module's contacts, or by creating electromagnetic coupling between the module antenna and the enhanced antenna, and vice versa. Thus, the module's antenna effectively communicates with the contactless read and / or write device via the enhanced antenna (through a resonant effect). Therefore, the only physical connections in this second type of card are located inside the module: the connection between the chip and the contacts, and the connection between the chip and the module antenna. All these connections are made inside the module. This avoids the need for an electrical connection between the antenna located in the card body and the chip located in the module.

[0009] Document WO2007026077 discloses a module including a flexible circuit having a front side carrying contacts and a back side carrying a module chip and an antenna. Holes (also called “wells” or “vias”) are then formed in the circuit, and the inner walls of these holes are metallized to electrically connect the front and back sides of the module, thereby connecting the contacts to both ends of the chip and the module antenna.

[0010] To integrate the module into the card, the antenna should be included within the module, the dimensions of which are defined by the ISO 7816-2 standard. Within these dimensions, it is necessary to provide areas on the back of the module for placing the chip, areas for metallized vias, and areas with bonding pads or solder pads (also known as "bonding tabs") for connecting the chip to the contacts and antenna. Furthermore, the antenna winding needs sufficient turns, a certain width, and minimal spacing between turns to achieve the desired electromagnetic characteristics.

[0011] Furthermore, to establish a reliable solder joint with sufficiently low resistance on the connectors that electrically connect these connectors to the chip, it is necessary to have one or more metal layers of sufficient thickness on these connectors. When these metal layers are electrochemically deposited, the current required for electrochemical deposition is provided by current leads on the front side, with the connectors dedicated to connecting the chip to the contacts providing current through contacts and metallized vias. The connectors dedicated to connecting the chip to the antenna can also be powered from the front side via current leads; optionally, the conductive traces on the front side are in the shape of strips and / or contacts, which are not used for connection to contact-based read and / or write devices and are used at least for one of the antenna windings. However, when the current required for electrochemical deposition passes through the antenna windings, relatively large non-uniformity is observed, on the one hand, between the thicknesses of the metal layers electrodeposited on the connectors dedicated to connecting the chip to the contacts, and on the other hand, large non-uniformity is observed between the thicknesses of the metal layers electrodeposited on the one or more connectors dedicated to connecting the chip to the antenna and powered through the antenna windings. This also means that in order to obtain a sufficiently thick electrodeposited metal layer, the deposition time needs to be significantly increased.

[0012] All these constraints make the development of new modular antenna designs very complex.

[0013] However, the inventors have developed a new double-sided circuit for chip cards that can achieve the electromagnetic properties required for the aforementioned applications, while also improving the method of manufacturing the circuit. Summary of the Invention

[0014] Therefore, a circuit is proposed that includes at least one additional metallized via, and a method wherein the additional metallized via is used during an operation of electrodepositing one or more layers of conductive material on at least one connector dedicated to connecting an antenna to a chip, prior to electrical isolation from the connector.

[0015] More specifically, a method for electrochemical metallization of double-sided circuitry for chip cards with contact- and contactless communication is proposed, wherein a flexible dielectric substrate is provided, comprising a front side and a back side. Contacts and current leads electrically connected to at least some of the contacts are arranged on the front side of the substrate. Connecting tabs and antennas are arranged on the back side of the substrate. Some of these connecting tabs are dedicated to connecting the chip to the contacts, while others are dedicated to connecting the chip to the antenna. In implementing this method, at least one layer of conductive material is deposited on at least some of the connecting tabs, while current is supplied to these connecting tabs via the current leads, contacts, and metallized vias, thereby establishing electrical continuity between the front and back sides of the substrate.

[0016] The method also includes, after the operation of electrochemically depositing at least one layer of conductive material, an operation of electrically isolating the metallized via (i.e., at least one of the additional metallized vias described above) from the bonding pad (e.g., a bonding pad specifically designed to connect the chip to an antenna).

[0017] Therefore, by means of the additional metallized via, current can be supplied directly from the front side of the substrate to the connector plate dedicated to connecting the chip to the antenna, without using the antenna windings to supply current to the connector plate. However, the use of this additional metallized via is temporary (during the electrochemical deposition operation). This additional metallized via is no longer used in the final module produced using the circuit obtained using the method according to the invention.

[0018] The method may also optionally include one and / or another of the following features, each of which is considered independently of each other or in combination with one or more other features:

[0019] - During the operation of electrochemically depositing at least one layer of conductive material, at least two metallization holes are used to metallize the internal antenna connector and the external antenna connector, and at least one of the two metallization holes is electrically isolated from the internal and external antenna connectors in the operation after the operation of electrochemically depositing at least one layer of conductive material.

[0020] - During the electrochemical deposition of at least one layer of conductive material, one identical contact located on the front side of the substrate is connected to two separate contact pieces and is used to power the two contact pieces through two metallized vias, and then at least one of the two metallized vias is electrically isolated from each contact piece;

[0021] - Use a laser beam to electrically isolate at least one metallized hole from a bonding pad dedicated to connecting the chip to an antenna;

[0022] - The laser beam moves across the surface of the conductive area of ​​the connector patch used to connect the metallized hole to the antenna without leaving the surface, thereby isolating the metallized hole from the rest of the connector patch used to connect the chip to the antenna.

[0023] According to another aspect, the present invention relates to a double-sided circuit for a chip card having contact- and contactless communication. The circuit includes a flexible dielectric substrate having a front and a back side. Contacts and current leads are located on the front side of the substrate. Antennas and connecting tabs are located on the back side of the substrate. Some connecting tabs are dedicated to connecting the chip to the contact, while others are dedicated to connecting the chip to the antenna. The circuit also includes at least one contact that closes at least two metallized vias. One of these metallized vias is connected to a contact connecting tab dedicated to connecting the chip to that contact, and the other of these metallized vias is electrically isolated from an antenna connecting tab dedicated to connecting the chip to the antenna, and is not used for conduction during the operation of the circuit in the module.

[0024] The circuit may also optionally include one and / or another of the following features, each of which is considered independently of each other or in combination with one or more other features:

[0025] - The external connection piece of the antenna is electrically connected to the antenna through two metallized holes, which are closed by conductive traces located on the front side of the substrate;

[0026] - The external connecting piece of the antenna is electrically connected to the antenna via a contact piece;

[0027] - The antenna forms at least one loop around a central region corresponding to the area used for chip mounting, and all contact tabs and antenna tabs are located around this central region, within the antenna loop; and

[0028] - At least one metallized hole electrically isolated from all connecting pieces, which is surrounded by an isolation area caused by abrasion produced by a laser beam. Attached Figure Description

[0029] Other features, objects, and advantages of the invention will become apparent from the following detailed description and with reference to the accompanying drawings, which are given by way of non-limiting example, and in which:

[0030] Figure 1 A chip card including an example of a module according to the invention is shown schematically in perspective view;

[0031] Figure 2 The previous view schematically illustrates the use of, for example Figure 1 The front or contact surface of the corresponding circuit section of the chip card module shown;

[0032] Figure 3 schematically shown in top view Figure 2 The circuit section shown, Figure 3 Corresponding to the back side of the substrate or the bonding surface (“bonding surface”) of the module;

[0033] Figure 4schematically shown in top view Figure 2 A variant of the circuit shown;

[0034] Figure 5 schematically shown in top view Figure 4 The circuit section shown;

[0035] Figure 6 The details of the metallized hole are schematically shown, which is electrically isolated by an isolation region caused by abrasion produced by a laser beam; and

[0036] Figures 7a to 7h schematically illustrate cross-sectional views of various steps of an exemplary embodiment of the method according to the present invention. Detailed Implementation

[0037] An exemplary embodiment of the circuit according to the present invention is described below.

[0038] like Figure 1 As shown, the chip card 1, which features contact and contactless communication, includes a module 2. Module 2 specifically includes a circuit 3 and a chip 100 (in...). Figure 1 (Not shown in the image). Module 2 is manufactured as a separate component and is inserted into a cavity formed in the body of card 1. The enhancement antenna (not shown) is integrated into the body of card 1 in a known manner.

[0039] Circuit 3 includes multiple contacts 5 (see Figure 7h), which are connected to chip 100. Figure 2 Circuit 3 is shown from the front 6 (contact surface). Figure 3 Circuit 3 is shown from its back side 7 (bonding side). Figure 2 and Figure 3 The circuit 3 shown corresponds to a double-sided printed circuit board for a "dual" card, with contacts 5 on the front side 6 and antenna 8 on the back side 7; only a portion of the circuit is actually shown. This portion essentially corresponds to the part required for production module 2, and multiple similar portions can be carried by a single, identical flexible substrate, for example, to implement the method according to the invention in roll-to-roll or roll-to-roll mode.

[0040] For example, there are six contacts 5: C1, C2, C3, C5, C6, and C7. Contact C1 is used to connect to the positive terminal of chip 100. Contact C2 is used to connect to the reset terminal of chip 100. Contact C3 is used to connect to the clock signal terminal 100 of chip 100. Contact C5 is used to connect to the ground terminal of chip 100. Contact C6 is not directly connected to chip 100 in the application targeted by this invention. Contact C7 is used to connect to the input / output terminal of chip 100.

[0041] In the final module 2, each contact C1, C2, C3, C5 and C7 is therefore connected to the terminal of the chip 100 through the metallized hole 40 of the contact connector 51 (that is, dedicated to connecting the contact to the chip), and the contact connector 51 is connected to the terminal of the chip 100 through the conductive line 70 (see FIG7h). Figure 3 C'1, C'2, C'3, C'5, and C'7 are used to indicate the connecting pieces 51 that are connected to the contact pieces 5 (C1, C2, C3, C5, or C7 respectively) through the metallized holes 40. Figure 2 and Figure 3 The proportions are different. This can be understood as the surface area occupied by antenna 8 being basically less than or equal to the surface area occupied by contact piece 5. Figure 3 It is actually a mirror of the real configuration. Figure 3 The right side corresponds Figure 2 (Since the right side in the diagram should be on the left, and vice versa), relative to the markings of the contact connecting pieces 51 (C'1, C'2, C'3, C'5, and C'7) of contact pieces 5 (C1, C2, C3, C5, and C7), as shown. Figure 2 As shown. Therefore, these metallized holes 40 are used simultaneously to connect the contacts 5 to the contacts 51 and the terminals of the chip 100 in the final module 2, but they are also used during one or more electrochemical metallization operations, thereby enabling the deposition of one or more layers of conductive material 60 (e.g., nickel or gold) on these contacts 51.

[0042] The chip should also be connected to both ends of the antenna 8. For this purpose, two internal and external antenna connecting tabs 52 (i.e., dedicated to connecting the antenna 8 to the chip 100) are provided on the back side 7. The antenna 8 includes a multi-turn winding wound around a central region, which corresponds to the area used to secure the chip 100. Advantageously, within the winding of the antenna 8, all contact connecting tabs 51 and antenna connecting tabs 52 are located around this central region.

[0043] In order to perform the electrochemical metallization of these internal and external antennas, these connecting pieces 52 must be connected to current leads 4 located on the front side 6. Current leads 4 are conductive traces that can establish an electrical connection between the electrodes of the electrodeposition unit and the contact piece 5. The external antenna connecting piece 52 is connected to the outer end 81 of the antenna 8 through two metallization holes 40 and conductive traces 9 connecting these two metallization holes 40 to the front side 6.

[0044] The conductive trace 9 is also connected to the current lead 4. The conductive trace 9 exists in the reference... Figure 2 and Figure 3In the described embodiment, but which may be removed and replaced with contact 5 or a portion thereof according to other embodiments. The internal antenna connector 52 is connected to the internal end 82 of the antenna 8 and the contact C5 (in the metallized hole 40I) through a metallized hole 40I. Figure 3 In the diagram, the metallized hole 40I is shown as electrically isolated from the internal antenna connector 52 (although it is indeed connected to the antenna connector 52 during the metallization stage). However, since the contact C5 is used for grounding in the final module 2, after the metallization operation, the metallized hole 40I is electrically isolated from the internal antenna connector 52, for example, by using a laser beam to remove the insulating ring 90 on the back surface 7 around the metallized hole 40I. Figure 4 An enlarged view of this region, including the metallized via 40I, is shown. (See attached image.) Figure 3 and 4 As shown, the laser beam moves along the surface of the conductive region connecting the metallized aperture 40I to the internal antenna connector 52 without leaving the surface, always surrounding the metallized aperture 40I. For example, the width L of the isolation region 90 caused by the abrasion of the conductive layer by the laser beam is 17 micrometers. Therefore, considering the accuracy, tolerance, and ease of setting of the laser beam parameters, it is preferable to set an area covered by the conductive layer within a radius R of at least 200 micrometers starting from the center of the metallized aperture 40I.

[0045] according to Figure 5 and Figure 6 In one variant, contact C5 is used for metallizing connector C'5, while contact C6, which is not used in the finished product and functional module, is used for metallizing connector 52 connected to the outer end 81 of antenna 8. The outer end 81 of antenna 8 is connected to contact C6 through a first metallization hole 40, and then connected to connector 52 through a second metallization hole of contact C6, thus eliminating the need for conductive traces 9 on the front side 6.

[0046] Figures 7a to 7h schematically illustrate various steps of an exemplary method for manufacturing circuit 3 according to the present invention, which is implemented in roll-to-roll or roll-to-roll mode.

[0047] As shown in Figure 7a, a structure is provided that includes a first conductive material sheet 10 laminated on an electrically insulating material substrate 20. This structure (also referred to as a "cladding") can be obtained by directly laminating the first conductive material sheet 10 and the electrically insulating material substrate 20 together. Alternatively, an adhesive material layer (not shown) may be applied or laminated onto the first conductive material sheet 10 and / or the electrically insulating material substrate 20 before laminating an adhesive material layer (not shown) between the first conductive material sheet 10 and / or the electrically insulating material substrate 20.

[0048] The first conductive material sheet 10 can be formed of a metal such as copper, steel, aluminum, or alloys of these metals. The first conductive material sheet 10 has a thickness of, for example, 18 micrometers or 25 micrometers. The electrically insulating material substrate 20 is formed of a dielectric material, such as a composite (glass-epoxy) material or a plastic (PET, PEN, polyimide, etc.) material. The electrically insulating material substrate 20 is typically very thin (with a thickness on the order of, for example, 100 micrometers) to maintain flexibility compatible with roll-to-roll or roll-to-roll methods used to manufacture the electronic module 3. The assembly consisting of the electrically insulating material substrate 20 covered by the first conductive material sheet 10 also forms a flexible circuit compatible with roll-to-roll or roll-to-roll methods used to manufacture the electronic module 3.

[0049] In the following steps, as shown in FIG7b, a thin film or adhesive material layer 30 is applied to the surface of the electrically insulating material substrate 20 opposite to the first conductive material sheet 10.

[0050] In the next step, as shown in Figure 7c, holes 40 and 40I are made through the entire structure obtained in the previous step. For example, holes 40 and 40I are made by punching holes in a direction substantially perpendicular to the plane of the structure.

[0051] In the next step, as shown in Figure 7d, a second conductive material sheet 50 is laminated onto the adhesive material layer 30 on the front side of the electrically insulating material substrate 20 opposite to the first conductive material sheet 10. The bottoms of these holes 40, 40I are closed by the second conductive material sheet 50, and the holes 40, 40I then become blind vias, also known as connection traps (as described below, these holes 40, 40I are metallized in subsequent steps to make them conductive).

[0052] The second conductive material sheet 50 can be formed of a metal such as copper, steel, aluminum, or alloys of these metals. The second conductive material sheet 50 has a thickness of, for example, 18 micrometers, 25 micrometers, or 35 micrometers.

[0053] In the following steps, as shown in FIG7e, patterns are formed in each of the first conductive material sheet 10 and the second conductive material sheet 50 by photolithography in a known manner. On the front side 6, that is, in the second conductive material sheet 50, these patterns include contacts 5 and current leads 4 (not visible in FIG7e). On the back side 7, that is, in the first conductive material sheet 10, these patterns mainly include contact connectors 51 and antenna connectors 51, as well as an antenna 8.

[0054] In the next step, as shown in FIG7f, one or more layers of conductive material 60 are electrochemically deposited on at least the contacts 5, connecting pieces 51, 52, and the vias 40. A portion of this step (e.g., the step for creating conductive vias) may have been performed prior to this step. The conductive material 60 may comprise one or more metals from nickel, gold, palladium, silver, and / or alloys thereof. A mask may be used optionally to selectively deposit some of these conductive materials on some areas but not others, or to have a greater or lesser thickness depending on the deposited area and / or the conductive material. The electrochemical deposition of this layer or these layers or the conductive material layer 60 is important to enable reliable soldering to the connecting pieces 51, 52, electrically connecting the chip 100 to the conductive lines 70 of the connecting pieces 51, 52. Current flows through the current leads 4 and the contacts 5 and connecting pieces 51, 52 located on the front side 6. The current flow between the metallized vias 40, 40I between the antenna 8 and any other traces located on the back surface 7 enables electrochemical deposition of one or more layers or conductive material layers 60 on the back surface 7. It can be noted that at this stage, some contacts 5 (e.g., on the right in FIG. 7f) are electrically connected to only one metallized via 40 and substantially electrically connected to the connecting piece 51, while at least another (on the left in FIG. 7f) is electrically connected to both metallized vias 40 and substantially electrically connected to the contact connecting piece 51 and the antenna connecting piece 51. For the contact 5 connected to both metallized vias 40, the two metallized vias 40 and the two connecting pieces 51, 52 are therefore short-circuited at least by the front surface 6.

[0055] The steps shown in Figure 7g mainly involve de-short-circuiting at least some of the metallized holes 40 and connecting tabs 51, 52 that are electrically connected to each other. Isolation (de-short-circuiting) is specifically performed on the holes that must be isolated. This can be advantageously performed using a laser beam. Advantageously, a ring 90 is created in one or more layers of conductive material 60 and also in the first conductive material sheet 10. Thus, the laser beam makes it possible to expose the electrically insulating material substrate 20, that is, to remove one or more layers of conductive material 60 and the first conductive material sheet 10 at the ring. Of course, other shapes can be created using the laser beam, but it is preferable to give a closed shape corresponding to the movement of the beam on the material that is structurally uniform. In practice, moving the laser beam from the area where the substrate of the electrically insulating material 10 is exposed to the area covered by one or more layers of conductive material 60, and to the first conductive material sheet 10, requires setting the laser beam parameters appropriately for each of these areas, which, while not impossible, requires a high degree of precision. In contrast, setting the laser beam is easier when the entire path of the laser beam along the electrically insulating material substrate 20 is clearing the same stack of layers.

[0056] As an alternative, the de-short-circuit step shown in Figure 7g can be performed by photolithography, for example by implementing steps such as applying an anti-electrodeposition film (“electroplating resist”), isolating and developing the film before metallization and etching.

[0057] Once the short-circuit removal step has been performed, other steps can be implemented. For example, as shown in Figure 7h, chip 100 is attached to the back side 7 of the electrically insulating material substrate 20. Next, wire 70 can be connected to chip 100 on one side and to connectors 51 and 52 on the other.

[0058] Then other known steps, not shown, can be performed. For example, the connecting wire 70 and the chip 100 are encapsulated in resin, the circuit 3 is cut to obtain a single-cut module 2, and the single-cut module 2 is integrated into a cavity milled out of the main card 1.

[0059] Since the operation of electrochemically depositing one or more layers of conductive material 60 on the antenna connector 52 no longer depends on the current flowing through the antenna 8, the antenna winding can be made thinner, and therefore the winding can have more turns. The turns can also be more compact.

[0060] Similarly, during the electrochemical deposition of one or more layers of conductive material 60, the antenna 8 can be connected to the front side 6 via metallization holes 40 at each end, thereby achieving a better distribution of the deposition of this or these layers or conductive material 60. This allows for a reduction in the inductance of the antenna 8, thereby improving its radio frequency performance.

Claims

1. An electrochemical metallization method for a double-sided circuit (3) of a chip card having contact and contactless communication, wherein a flexible dielectric substrate (20) is provided, the flexible dielectric substrate (20) comprising a front side (6) and a back side (7), the front side (6) having contacts (5) and current leads (4) electrically connected to at least some of the contacts (5), the back side (7) having an antenna (8), a first connecting piece and a second connecting piece, wherein the first connecting piece (51) is dedicated to connecting a chip (100) to the contacts (5), and the second connecting piece (52) is dedicated to connecting the chip (100) to the antenna (8), the method comprising: electrochemically depositing at least one layer of conductive material (60) on at least one of the first connecting piece and the second connecting piece, while providing current to at least one of the first connecting piece and the second connecting piece via the current leads (4), establishing electrical continuity between the front side (6) and the back side (7) through the contacts (5) and metallization holes (40), characterized in that, The method includes, after an operation of electrochemically depositing at least one layer of conductive material (60), an operation of electrically isolating at least one of the metallized holes (40) from the second connecting piece (52) dedicated to connecting the chip (100) to the antenna (8).

2. The method according to claim 1, wherein during the operation of electrochemically depositing at least one layer of the conductive material (60), the inner antenna connector in the second connector and the outer antenna connector in the second connector are metallized using at least two metallization holes (40), and in the operation after electrochemically depositing the at least one layer of the conductive material (60), at least one of the two metallization holes (40) is electrically isolated from the inner antenna connector and the outer antenna connector.

3. The method according to any one of the preceding claims, wherein, During the electrochemical deposition of at least one layer of the conductive material (60), the two first connecting pieces are powered through the two metallized holes (40) using one and the same contact (5) connected to the front side (6) of the two separate first connecting pieces and the second connecting piece, and then at least one of the two metallized holes (40) is electrically isolated from each of the first connecting pieces and the second connecting piece.

4. The method of claim 1, wherein the operation of electrically isolating the at least one metallized hole (40) from the second connecting piece (52) dedicated to connecting the chip (100) to the antenna (8) is achieved by using a laser beam.

5. The method of claim 4, wherein the laser beam moves over a conductive region of the second connecting piece (52) dedicated to connecting the metallized hole (40) to the antenna (8) without leaving the surface, and the laser beam moves around the metallized hole (40) to isolate the metallized hole (40) from the remainder of the second connecting piece (52) dedicated to connecting the chip (100) to the antenna (8).

6. A double-sided circuit for a chip card with contact and contactless communication, comprising a flexible dielectric substrate (3) having a front side (6) and a back side (7), a contact (5) and a current lead (4) on the front side (6), an antenna (8), a first connecting piece (51), and a second connecting piece (52) on the back side (7); wherein the first connecting piece (51) is dedicated to connecting a chip (100) to the contact (5), and the second connecting piece (52) is dedicated to connecting the chip (100) to the antenna (8); characterized in that, It includes at least one contact (5) that closes at least two metallized holes (40), one of the metallized holes (40) being connected to a first connecting piece (51) dedicated to connecting the chip (100) to the contact (5), and the other of these metallized holes (40) being electrically isolated from a second connecting piece (52) dedicated to connecting the chip (100) to the antenna (8).

7. The circuit according to claim 6, wherein the outer connecting piece (52) of the second connecting piece of the antenna (8) is electrically connected to the antenna (8) through the two metallized holes (40), the two metallized holes (40) being closed by conductive traces located on the front side (6).

8. The circuit according to claim 6, wherein, The outer connecting piece (52) of the second connecting piece of the antenna (8) is electrically connected to the antenna (8) via the contact piece (5).

9. The circuit according to any one of claims 6 to 8, wherein, The antenna (8) forms at least one loop around a central region corresponding to the fastening area of ​​the chip (100), and all the first connecting pieces and the second connecting pieces are located around the central region within one of the loops of the antenna.

10. The circuit of claim 6, wherein at least one of the metallized holes (40) electrically isolated from all the first and second connecting pieces (51, 52) is surrounded by an isolation region (90) caused by abrasion produced by a laser beam.

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