METHOD FOR MANUFACTURING CHIP CARD MODULES AND TAPE MADE OF FLEXIBLE MATERIAL TO SUPPORT SUCH MODULES

Description

technical field

[0001] The invention relates to the field of smart cards. Smart cards are well known to the public, who have multiple uses for them: payment cards, SIM cards for mobile phones, transport cards, identity cards, etc. State of the art

[0002] For example, smart cards include transmission means for transmitting data from the chip to a card reader (read) or from that reader to the card (write). These transmission means can be "contact," "contactless," or dual-interface when they combine the two previous means. The invention relates in particular to the field of dual-interface smart cards.

[0003] Dual-interface smart cards typically consist of a rigid plastic core, or card body, made of PVC, PVC / ABS, PET, or polycarbonate. This core contains an electronic module and an antenna, each manufactured separately. The electronic module comprises a printed circuit board, usually flexible, with an integrated circuit (IC) containing an electronic chip. Contact pads are electrically connected to the chip and are flush with the surface of the card body, allowing for electrical contact with a card reader. Dual-interface smart cards also include at least one antenna for transmitting data between the chip and a radio frequency (RF) system, enabling contactless data reading and writing.The use of a polymer loaded with conductive particles to establish a connection between elements of a smart card is known in particular from EP3567527A1, FR3009411A1, US2011 / 011939A1 and WO2015 / 097400A1.

[0004] In dual-interface smart cards, it is relatively difficult to provide a robust and reliable electrical connection between the module and the antenna that can withstand the handling a smart card may undergo. This connection must also be implemented in a sufficiently cost-effective manner.

[0005] In addition, smart card modules may need to be stored on substrates for a relatively long time, up to several months, before being used to finalize smart card manufacturing, including integrating each module into a card body and connecting each module to an antenna integrated into the card body.

[0006] To at least partially meet the requirements mentioned above, a method for manufacturing a smart card module is proposed, comprising the provision of a dielectric substrate suitable for creating flexible electrical circuits. The dielectric substrate has a thickness defined by a front face and a back face, both forming the main faces of the substrate. Furthermore, the method includes the deposition of a polymer material containing conductive particles. This deposition can be carried out either in connection wells to connect with conductive areas located on the front face, or directly onto conductive areas located on the back face.Thus, the polymer material containing conductive particles can be deposited in at least two connection wells within the substrate's thickness. Each of these connection wells is at least partially sealed on the substrate's front face by a contact area formed in a first metallic conductive sheet (which is therefore deposited on the front face of the flexible electrical circuit, corresponding to the module's contact side). Alternatively, the polymer material containing conductive particles can be deposited on a conductive area formed in a second metallic sheet resting on the back face (or "bonding side"). Therefore, the polymer material containing conductive particles can be deposited both in a connection well and on a conductive area located on the back face.The deposition is carried out in a manner adapted so that the polymer material comprising conductive particles forms after deposition an excess thickness on the back face (i.e. in excess thickness on the back face itself if it does not have a second conductive sheet - case of a circuit for a single-sided module - or in excess thickness relative to the second conductive sheet - case of a circuit for a double-sided module).

[0007] After deposition, the polymer material containing conductive particles undergoes curing. This curing occurs spontaneously or through one or more additional operations. More precisely, the polymer material containing conductive particles cured immediately after deposition, either spontaneously due to its rheological properties and / or thermal transitions, or through one or more additional operations designed to initiate and / or complete all or part of its polymerization or crosslinking (e.g., irradiation under ultraviolet radiation, exposure to a heat source, etc.). Curing occurs prior to a storage operation during which at least one portion of the substrate, equipped with the first conductive layer and the polymer material containing conductive particles, is positioned above or below another portion of the substrate.For storage, the substrate can be rolled up or stacked in sections as sheets. Optionally, the process includes crosslinking the conductive polymer material after it has been rolled or stacked. This crosslinking process gives the conductive polymer material its final rheological properties.

[0008] Thanks to the modification of the viscoelastic properties of the polymer material including conductive particles during the setting process, after deposition, it is possible to store the modules (finished but not yet individualized) on strips of flexible material (in this case the dielectric substrate) stored with an overlap of certain portions of substrate, without the polymer material including conductive particles adhering to the portion of the strip located below or above them, or to an intercalary material that would be placed between the portions of substrate rolled or stacked on top of each other.

[0009] For example, if the polymer material containing conductive particles is a thermosetting polymer, an additional operation to at least partially crosslink the polymer material can be performed. This crosslinking operation can be carried out while the substrate strip is already wound upon itself or in stacked sheets. In the case of thermal crosslinking, the applied temperature is high enough (e.g., above 50°C) to give the polymer material its final properties, but low enough (e.g., below 150°C) so as not to alter the other components of the module or cause the uncrosslinked polymer to flow.

[0010] The polymer containing conductive particles, thus hardened either by thermal crosslinking, solidification upon cooling, or polymerization, becomes a material with a storage modulus less than or equal to 10⁸ Pa and greater than or equal to 10³ Pa, under oscillatory loading at a frequency of 1 Hz and at a temperature between 120 and 170°C. These properties of the hardened polymer containing conductive particles remain compatible with a reactivation of adhesion and / or a reactivation of tackiness sufficient to connect each module to an antenna by applying at least one pressure to the antenna's connection pads, and more specifically, at least to the areas where the polymer containing conductive particles is located.

[0011] When pressure is applied to connect the module to an antenna, an increase in operating temperature can facilitate the reactivation of the adhesive properties of the polymer containing conductive particles. For example, this operation is performed simultaneously with, or instead of, attaching the module to the board body using a hot-melt adhesive.

[0012] The process mentioned above also advantageously includes one or more of the following characteristics, considered independently of each other or in combination with one or more others: The deposition of the polymer material comprising conductive particles is carried out at a temperature between 20 and 120°C, for example at a temperature between 20 and 70°C; the polymer material comprising conductive particles is a resin having a viscosity, at the time of its deposition, between 1000 mPa.s and 100000 mPa.s, under oscillatory shear stress at a frequency of 10Hz at 25°C; for example, the polymer material is a one-component resin or a two-component resin; alternatively, the polymer material is a thermoplastic resin having a melting temperature between 90 and 140°C, and a viscosity at the time of its deposition, between 1000 and 100000 mPa.s under oscillatory shear stress at a frequency of 10Hz at 25°C, said deposition being carried out at a temperature between 90 and 140°C; alternatively, the polymer material is a pressure-sensitive polymer having a viscosity, at the time of its deposition, between 1000 mPa.s and 100000 mPa.s under oscillatory shear stress at a frequency of 10Hz at 25°C; the polymer material comprising conductive particles has thixotropic properties characterized by an increase in viscosity up to a value at least equal to 300000 mPa.s (and preferably greater than 500000 mPa.s), under oscillatory shear and at a frequency of 0.1Hz at a temperature of 25°C, in a time interval ranging from 0 seconds to 600 seconds after the deposition of the polymer material: such thixotropic properties allow its spontaneous freezing; in this case, the process may not include an additional freezing operation; the freezing of the polymer material after its deposition is obtained by crosslinking under ultraviolet radiation, in a time less than 600 seconds after this deposition; .

[0013] According to another aspect of the invention, a method for interconnecting an antenna and a smart card module is proposed, according to claim 10, comprising the supply of a smart card module obtained by a process as mentioned above, the supply of a card body in which is integrated an antenna having at least two connection pads, and the connection of at least one of the two connection pads with a contact area at least partially blocking a connection well in which polymer material comprising conductive particles is deposited, or with a conductive area formed in the second conductive sheet resting on the back face and on which polymer material comprising conductive particles is deposited, this connection being made by applying a pressure of between 0.5 and 5 bar, with a thermode having a temperature of between 170 and 210°C and for a time of less than 3 seconds.

[0014] A strip of flexible material is described below, supporting a plurality of smart card modules obtained by a process as mentioned above, wound on itself or in plates stacked one on top of the other (with or without intercalated material between two superimposed layers of this strip).

[0015] A dual-interface smart card is described below, comprising a module and an antenna interconnected using a method as mentioned above.

[0016] Other features and advantages of the invention will become apparent upon reading the detailed description and accompanying drawings, in which: FIG. 1 schematically represents in perspective an example of a dual interface smart card in which the module has not yet been integrated, the module being represented three times, twice with the contact face visible and once with the connection face visible; FIG. 2 schematically represents an example of the implementation of a manufacturing process, from reel to reel, of a smart card module; FIG. 3 represents in cross-section, partially and schematically, an example of the implementation of one of the operations of the process shown on the figure 2 , this operation corresponding to the filling of certain connection wells with a material comprising electrically conductive particles; FIG. 4 represents in cross-section, partially and schematically, before winding onto a storage reel, a strip of flexible material supporting a plurality of smart card modules obtained by the process shown on the figure 2 ; FIG. 5 represents in cross-section, partially and schematically, an example of the implementation of an embedding operation for a smart card module obtained by the process shown on the figure 2 ; And FIG. 6 schematically represents the footprint of the material comprising electrically conductive particles on tracks at one end of an antenna.

[0017] As depicted on the figure 1 The invention can be used to manufacture a smart card 1 (of the bank card type or otherwise). This card 1 comprises a module 2 intended to be inserted into a cavity 3, for example, milled into the body of the card 1. This module 2 consists of a flexible electrical circuit comprising a dielectric substrate 4. The substrate 4 is initially in the form of a strip of material having a first and a second principal face that are essentially parallel to each other and separated by the thickness of the substrate 4. The substrate 4 has a thickness, flexibility, and suppleness compatible, on the one hand, with its implementation in a continuous roll-to-roll manufacturing process and, on the other hand, with the norms and standards determining the maximum thickness of finished smart cards.The example of an implementation of the process according to the invention described below and illustrated in the figures relates to a reel-to-reel (or roll-to-roll) implementation of the substrate 4, and / or one comprising at least one storage operation on a reel. Alternatively, the process according to the invention can be implemented with a substrate 4 in the form of a sheet, and / or can comprise at least one storage operation in substrate sheets. The substrate 4 is generally thin. Its thickness, advantageously less than 400 µm, is, for example, on the order of 20 to 200 µm, or even between 50 and 150 µm. This substrate 4 is, for example, made of a flexible strip of plastic material (polyimide, PET, PEN, PVC, etc.) or composite material (glass-epoxy).

[0018] On one face of this substrate 4, called the front face 5 (or contact face), conductive areas electrically insulated from each other are formed in a first conductive sheet 6. These conductive areas may include contacts for establishing contact with a card reader, as well as other conductive areas not used in the connection with the card reader contacts. The conductive areas can be formed by etching the first conductive sheet 6. This sheet is made of an electrically conductive material such as a copper alloy (alternatively, aluminum, an aluminum alloy, or steel may also constitute this electrically conductive material). In this case, prior to etching, the first conductive sheet 6 is bonded and / or laminated to the substrate 4, with or without an adhesive layer between the substrate 4 and the first conductive sheet 6.Alternatively, the conductive areas can be made by cutting (the so-called "leadframe" technique according to Anglo-Saxon terminology) in the first conductive sheet 6, prior to its gluing and / or lamination onto the substrate 4 (also with or without a layer of glue between the substrate 4 and the first conductive sheet 6).

[0019] In all cases, the first conductive sheet 6 is therefore ultimately supported by the substrate 4, with one face facing a first principal face, corresponding to the front face 5 of the substrate 4 (see figures 3 à 5 ), while the other side is designed to establish an electrical contact connection with a smart card reader. The first conductive sheet 6 can receive various metallization layers (nickel, gold, palladium, etc.) on one or both of its faces. The quality of the face of the first conductive sheet 6 (generally metallized) facing the substrate 4 is important, particularly to ensure a good connection to the chip 7, for example by soldering conductive wires 8. The substrate 4 with the conductive areas 6 constitutes a flexible metallized electrical circuit.

[0020] On the second main face of the substrate 4, called the rear face 9 (or connection face), the substrate 4 supports the electronic chip 7. The mechanical attachment of the chip 7 to the substrate 4 is achieved by at least one known technique such as die-attachment, and its electrical connection to the conductive pads is achieved by at least one known technique such as flip-chip technology, wire bonding, etc. In the embodiment described below, wire bonding is used as an example.

[0021] An antenna 10 (for example, Class 1 or Class 2 according to ISO 14443-1) may have several turns and is inserted into the body of the card 1, between two laminated layers. The ends 11 of this antenna 10 are accessible in the cavity 3, after milling of the cavity, for connection with the chip 7.

[0022] The conductive areas intended to form contacts are connected to chip 7 with conductive wires 8 (not visible on the figure 1 , but represented on the figures 4 et 5 ) through connection wells 12 formed in the substrate 4. These connection wells 12 are, for example, made by mechanically drilling the substrate 4 before laminating the first conductive sheet 6 to the substrate 4. Alternatively, they can be made by laser (for example, when using a laminated substrate, such as a copper laminate or "copperclad"). The first conductive sheet 6 then at least partially covers the connection wells 12. The face of the first conductive sheet 6 facing the substrate 4 thus forms the bottom of these connection wells 12. The connection wells 12 then form blind holes and allow access to the front face 5 from the rear face 9, with only the first conductive sheet 6 on the front face 5.

[0023] The dimensions and positions of the conductive pads are defined to comply with ISO 7816-2, among other standards. For example, according to ISO 7816-2, the conductive pads are designated C1 to C8 for an eight-contact module 2. In this case, conductive pads C1, C2, C3, C5, C6, and C7 are intended to establish communication with chip 7 via contact on the front panel 6. This leaves at least two conductive pads, each with a connection well 12 underneath, which can be used to connect the antenna 10 to chip 8. For this purpose, as shown in the figure 3 , a polymer material 13 comprising conductive particles is deposited in each of these two connection wells 12. Each of these two connection wells 12 is filled with this polymer material 13 by dispensing or by jetting a drop of it (alternatively a screen printing method may be used).

[0024] When deposited in the connection wells 12, the polymer material 13 has thixotropic properties such that they allow an increase, for a time ranging from 0 seconds to 600 seconds after deposition, in viscosity up to a value greater than 300000 mPa.s, under oscillatory shear and at a frequency of 0.1Hz. Example 1: Two-component epoxy adhesive

[0025] In a first example, a chip 7 is fixed to the rear face 9 of the substrate 4 using a chip fixation technology, as mentioned above. The chip 7 is electrically connected to certain conductive areas using connecting wires 8. The chip 7 and its connecting wires 8 are encapsulated in a crosslinked encapsulation resin 15 after deposition under ultraviolet radiation. This crosslinking can be carried out in two stages: a first stage shortly after deposition and a second stage, called post-crosslinking, intended to optimize its mechanical properties.

[0026] The polymer material 13 is a two-component resin prepared by mixing the two parts under the conditions recommended by the supplier. Using dispensing equipment, the mixture thus prepared, constituting the polymer material 13 and containing conductive particles, is deposited at room temperature into at least one connection hole 12. The polymer material 13 is, for example, a two-component epoxy resin consisting of an epoxy polymer and conductive particles such as silver particles.

[0027] At the time of its deposition in the connection wells 12, the polymer material 13 comprising conductive particles has a viscosity whose value is compatible with the deposition of the polymer material 13 by dispensing, in the connection holes 12. For example, this viscosity value is between 30000 and 60000 mPa.s under oscillatory shear stress carried out at 25°C at a frequency of 10Hz.

[0028] Immediately after dispensing the polymer material 13 containing conductive particles, its viscosity increases beyond 500,000 mPa·s. This increase in viscosity allows the material 13 to solidify without it having been cross-linked at this stage of the process. Once solidified, the shape of the droplet of polymer material 13 remains stable in the absence of stress (such as finger pressure, liner pressure, contact with a foreign body, etc.). This increase in viscosity allows the substrate to be wound into a coil without altering the shape of the polymer material 13 as initially given during dispensing.

[0029] The flexible substrate strip 4, thus wound upon itself, is heated to a temperature of 70°C for 12 hours. This operation, initially intended to ensure the post-crosslinking of the encapsulation resin 15, is advantageously used to crosslink simultaneously the conductive polymer material 13 previously deposited by dispensing.

[0030] At the end of this crosslinking operation, the polymer material 13 has a conservation modulus, under oscillatory tensile stress at 1Hz, equal to 3.5 x 10 7< Pa, for a measurement temperature between 120 and 170°C.

[0031] During the insertion (operation consisting of integrating the module 2 into the body of a smart card 1), the polymer material 13, which has retained the viscoelastic properties mentioned above, establishes an elastic electrical connection with each of the ends 11 of the antenna 10. A pressure is applied to the module 2, at least at the level of the connection wells 12 filled with polymer material 13. This pressure, advantageously close to or equal to 1 bar, is applied, for a time advantageously close to or equal to 1 second, with a thermode whose temperature is between 170 and 190°C. Example 2: One-component epoxy resin

[0032] According to a second example, the process described above in relation to the first example (two-component resin) differs essentially from the latter only in that the polymer material 13 is a one-component epoxy resin. For example, it is a resin whose trade name is included in the following list: Henkel CA3556HF, Henkel ICP8282. Example 3: Thermoplastic having a melting point between 100°C and 140°C.

[0033] According to a third example, a chip 7 is fixed to the rear face 9 of the substrate 4 using a chip fixing technology, as mentioned above. The chip 7 is electrically connected to certain conductive areas using connecting wires 8. The chip 7 and its connecting wires 8 are encapsulated in a cross-linked encapsulation resin 15, after deposition, under ultraviolet radiation.

[0034] Polymer material 13 is, for example, a conductive adhesive consisting of a thermoplastic polymer and conductive particles. For example, it is a thermoplastic polyester resin loaded with silver particles.

[0035] The polymer material 13 comprising conductive particles has a melting temperature of 100°C and its deposition in the connection wells 12 is then carried out at a temperature of 120°C.

[0036] At the time of its deposition in the connection wells 12, the polymer material 13 comprising conductive particles has a viscosity of less than 100000mPa.s.

[0037] Immediately after dispensing the polymer material 13 containing conductive particles, and within a time interval of less than 600 seconds, the temperature of the polymer material 13 is lowered below its melting point. This results in recrystallization, which increases the viscosity of the polymer material 13 to a value exceeding 300,000 mPa·s. At this viscosity, the shape of the droplet of polymer material 13 deposited at the connection holes 12 remains stable under no stress. The increased viscosity then allows the substrate 4 to be wound into a coil without altering the shape of the polymer material 13 as initially dispensed.

[0038] The polymer material 13 has a conservation modulus, at 1Hz, less than or equal to 10⁸ Pa and greater than or equal to 10³ Pa, at a temperature between 120 and 170°C.

[0039] During the insertion, the polymer material 13, whose viscoelastic properties are those mentioned above, establishes an elastic electrical connection with each of the ends 11. A pressure is applied to the module 2, at least at the level of the connection wells 12 filled with polymer material 13. This pressure, advantageously close to or equal to 1 bar, is applied for a time of 2.5 seconds with a thermode having a temperature between 170 and 190°C. Example 4: Pressure-sensitive polymer

[0040] According to a fourth example, a chip 7 is fixed to the rear face 9 of the substrate 4 using a chip fixing technology, as mentioned above. The chip 7 is electrically connected to certain conductive areas using connecting wires 8. The chip 7 and its connecting wires 8 are encapsulated in a cross-linked encapsulation resin 15, after deposition, under ultraviolet radiation.

[0041] At room temperature, the polymer material 13, comprising conductive particles, is deposited into at least one connection hole 12. For example, the polymer material 13, comprising conductive particles, corresponds to a formulation of UV-curable acrylic monomers and oligomers loaded with conductive particles. For example, this is the resin marketed under reference 127-41 by Creative Materials.

[0042] At the time of deposition of the polymer material 13 containing conductive particles, its viscosity is on the order of 20,000 to 30,000 mPa·s, under the following measurement conditions: Oscillatory shear stress, at a frequency of 10 Hz and a temperature of 25°C. This viscosity allows the polymer material 13 containing conductive particles to be dispensed into the connection holes 12.

[0043] Immediately after dispensing the polymer material 13 containing conductive particles, the flexible strip of the substrate 4 is exposed, for a period ranging from a few seconds (e.g., 2 seconds) to one minute, to ultraviolet radiation generated by a mercury vapor lamp. The polymer material 13 thus polymerized forms a pressure-sensitive adhesive. After this polymerization, the shape of the droplet of polymer material 13 deposited at the connection holes 12 remains stable.

[0044] Optionally, the encapsulation resin 15 undergoes a post-crosslinking operation by exposing it to a temperature of 70°C for 12 hours.

[0045] At the end of polymerization, the polymer material 13 has a conservation modulus, under oscillatory shear stress at 1Hz, of the order of 10 3< Pa.s, at a temperature between 120 and 170°C.

[0046] During insertion, the polymer material 13 establishes an elastic electrical connection with each of the ends 11 of the antenna 10. Pressure is applied to the module 2, at least at the connection wells 12 filled with polymer material 13. This pressure, advantageously close to or equal to 1 bar, is applied for a duration advantageously close to or equal to 2 seconds, using a thermode with a temperature between 170 and 210°C. In this example, the tackiness of the polymer material 13 contributes to generating a permanent adhesion between the polymer material 13 and the ends 11 of the antenna 10.

[0047] In all cases, and particularly for the examples mentioned above, the deposition of the droplet of polymer material 13 is carried out in such a way that the polymer material 13, comprising conductive particles, forms a thicker dome on the rear face 9 after deposition. This operation of deposition of a droplet of polymer material 13 into a connection well 12 can be carried out continuously, from roll to roll, as illustrated in the figure 2 , after photolithography operations (to form the conductive areas in the first conductive sheet 6), electrodeposition of metallic layers (nickel, gold and / or palladium for example), etc.

[0048] Advantageously, the polymer material 13, after being deposited in the connection wells 12 and a possible freezing or hardening operation, only develops adhesion properties when subjected to pressure.

[0049] Following the treatments corresponding to the process described and illustrated with the examples above, a flexible material strip 14 is obtained, supporting a plurality of smart card modules. This strip 14 is then wound upon itself, with or without an interlayer material between two superimposed layers or turns of this strip 14. In other words, due to its properties after freezing or hardening, the polymer material 13 does not adhere to the surfaces of the strip 14 that come into contact with it during the winding and storage of the strip 14 in a roll. Nevertheless, an interlayer material can be used to provide mechanical protection for the smart card modules.

[0050] A portion of this strip 14 is shown on the figure 4 This portion of the strip 14 corresponds, for example, to what is obtained after unwinding the strip 14, in preparation for inserting the modules 2 it contains. In the portion shown, there are two modules 2. Each module 2 has a chip 7 connected to contacts etched in the first conductive sheet 6 by conductive wires 8 passing through connection wells 12. Each chip 7, as well as the conductive wires connected to it, are protected by an encapsulation resin 15 (known as "glob top"). Outside the encapsulation resin 15, and therefore not covered by it, there remain at least two connection wells 12 for each module 2. Each of these two connection wells 12 is filled with a fixed, hardened polymer material 13. The polymer material 13 protrudes, in excess, on the rear face 9.For example, the polymer material 13 protrudes by a height of between 60 and 250 micrometers, for example this height is close to 150 micrometers.

[0051] Before insertion, the Module 2s are individualized. As shown on the figure 5 Each module 2 is inserted by placing it in a cavity 3 previously milled in the body of the card 1. The milling process notably exposes the ends 11 of the antenna 10. These ends 11 are, for example, each provided with a conductive pad to which each is connected (for example, by soldering). Alternatively, the ends 11 form zigzags. As schematically illustrated by the figure 6 Such zigzags have tracks 20 (formed of wires embedded in a support or of strips etched into a conductive layer supported by an insulating substrate). The spacing between the tracks 20 determines a pitch. These tracks 20 are spaced from each other with a certain more or less regular pitch (on the figure 6 (The ends of the 20 tracks connected to form the zigzag are not shown). On the left of the figure 6The tracks 20 are spaced apart by a pitch P1 greater than the pitch P2 of the tracks 20 shown on the right. As a result, the dome of material 13, containing conductive particles and filling a connection hole 12, electrically connects fewer tracks 20 in the configuration shown on the left than in the configuration shown on the right (3 tracks on the left, 4 tracks on the right). Thus, advantageously, the pitch of the tracks 20 forming a zigzag is less than or equal to 250 micrometers and, more preferably, close to or equal to 200 micrometers. If the tracks are too far apart, the material 13 containing conductive particles, particularly if it is not centered with respect to the zigzag, may no longer establish a sufficient electrical connection with the ends 11 of the antenna 10.

[0052] Optionally, module 2 is glued into its cavity 3 using a heat-activated adhesive and pressure is applied to the polymer material 13 and to the heat-activated adhesive during the operation of gluing module 2 into its cavity 3.

[0053] In essence, the polymer material 13, at the time of its deposition in a connection well 12, has a viscosity advantageously less than 100,000 mPa·s, measured under oscillatory shear stress at 25°C and a frequency of 10 Hz. After this deposition, the polymer material 13 sets spontaneously or undergoes a setting process to achieve a storage modulus, under oscillatory shear stress at 1 Hz, of between 10⁻³ Pa·s and 10⁸ Pa·s, at a temperature between 120 and 170°C. At the time of insertion, the polymer material 13 is subjected to pressure, and possibly heating, to reactivate its adhesive and / or tackiness properties.

[0054] A method for manufacturing a single-sided module 2, i.e., one comprising only a first conductive layer 6 on its front face, has been described above. In this case, the polymer material 13 is deposited in connection wells 12. However, the invention also relates to a method for manufacturing a double-sided module 2. In this case, the substrate 4 comprises a first and a second conductive layer, respectively on each of its main faces. The polymer material 13 can then be deposited onto conductive areas formed in the second conductive layer, which is therefore located on the rear face of the substrate 4. The operations subsequent to the deposition of the polymer material 13 onto these conductive areas are analogous to those described above in relation to the production of a single-sided module.

Claims

1. A method for manufacturing at least one smart card module (2) of a smart card (1) comprising • providing a flexible dielectric substrate (4) in tape form, the substrate (4) having a thickness delimited by a front face (5) and a rear face (9), both forming the main faces of the substrate (4), with at least one conductive land formed in a first conductive foil (6) resting on the front face (5), • depositing a polymer material (13) comprising conductive particles in a suitable manner so that the polymer material (13) comprising conductive particles forms, after deposition, an extra thickness on the rear face (9), this deposition being carried out according to at least one of the following two options: ∘ in at least one connection well (12) formed in the thickness of the substrate (4), said at least one connection well being at least partially closed off at the level of the front face (5) of the substrate (4) by a conductive land formed in the first conductive foil (6), ∘ on a conductive land formed in a second conductive foil resting on the rear face (9), characterised in that • the polymer material (13) comprising conductive particles has, at the moment of deposition, a viscosity comprised between 1000 and 100000 mPa.s, measured under oscillatory shear stress at 25°C and at a frequency of 10Hz, • the method comprises a step of setting the polymer material (13) comprising conductive particles, and • a storage operation, comprising the winding of the substrate (4) onto itself, provided with the first conductive foil and the polymer material (13) comprising conductive particles, or the stacking of portions of the substrate (4) in the form of sheets, this storage operation succeeding the setting step and preceding an operation consisting of integrating said at least one module (2) into the body of a smart card (1), and during which storage operation at least one portion of the substrate (4), provided with the first conductive foil and the polymer material (13) comprising conductive particles, is positioned above or below another portion of the substrate (4), this other portion of the substrate (4) originating either from the substrate (4) wound onto itself, or from a sheet of substrate (4) placed above or below said at least one portion of the substrate (4), provided with the first conductive foil and the polymer material (13) comprising conductive particles, the polymer material (13) comprising conductive particles being configured by the setting step not to adhere to this other portion of the substrate (4) and to allow, by at least the application of pressure, the connection of said at least one module (2) to an antenna (10).

2. Method according to claim 1, wherein the polymer material (13) comprising conductive particles is a material having a storage modulus, after setting, of less than or equal to 10^6 Pa and greater than or equal to 10^3 Pa, under oscillatory stress at a frequency of 1 Hertz, and at a temperature comprised between 120 and 170°C.

3. Method according to any one of the preceding claims, wherein the deposition of the polymer material (13) comprising conductive particles is carried out at a temperature comprised between 20 and 70°C.

4. Method according to any one of claims 1 and 2, wherein the polymer material (13) comprising conductive particles is a thermoplastic resin having a melting temperature comprised between 90 and 140°C and wherein this deposition of the polymer material (13) is carried out at a temperature comprised between 90 and 140°C.

5. Method according to any one of claims 1 to 3, wherein the polymer material (13) comprising conductive particles is a pressure-sensitive adhesive.

6. Method according to any one of the preceding claims, wherein the polymer material (13) comprising conductive particles has thixotropic properties characterised by a viscosity becoming greater than 300000 mPa.s, under shear stress at a frequency of 0.1Hz, after a time ranging from 0 seconds to 600 seconds following the moment of deposition of the polymer material (13).

7. Method according to any one of the preceding claims, wherein the polymer material (13) comprising conductive particles undergoes a setting operation by being exposed to ultraviolet radiation.

8. Method according to any one of the preceding claims, wherein the polymer material (13) comprising conductive particles undergoes, after deposition, a heating operation.

9. Method according to any one of the preceding claims, wherein the polymer material (13) comprising conductive particles forms an extra thickness on the rear face (9) whose height is comprised between 60 and 250 micrometres.

10. Method for interconnecting an antenna (10) and a smart card module (2) of a smart card (1) comprising • providing a flexible dielectric substrate (4) in tape form, the substrate (4) having a thickness delimited by a front face (5) and a rear face (9), both forming the main faces of the substrate (4), with at least one conductive land formed in a first conductive foil (6) resting on the front face (5), • depositing a polymer material (13) comprising conductive particles in a suitable manner so that the polymer material (13) comprising conductive particles forms, after deposition, an extra thickness on the rear face (9), this deposition being carried out according to at least one of the following two options: ∘ in at least one connection well (12) formed in the thickness of the substrate (4), said at least one connection well being at least partially closed off at the level of the front face (5) of the substrate (4) by a conductive land formed in the first conductive foil (6), ∘ on a conductive land formed in a second conductive foil resting on the rear face (9), • providing a card body in which is integrated an antenna (10) comprising at least two connection ends (11), • connecting at least one of the two connection ends (11) with said conductive land formed in the first conductive foil (6) at least partially closing off said at least one connection well (12) in which is deposited the polymer material (13) comprising conductive particles, or with said conductive land formed in the second conductive foil resting on the rear face (9) and on which is deposited the polymer material comprising conductive particles, this method being characterised in that • the polymer material (13) comprising conductive particles has, at the moment of deposition, a viscosity comprised between 1000 and 100000 mPa.s, measured under oscillatory shear stress at 25°C and at a frequency of 10Hz, • it comprises a step of setting the polymer material (13) comprising conductive particles, and a storage operation, comprising the winding of the substrate (4) onto itself, provided with the first conductive foil and the polymer material (13) comprising conductive particles, or the stacking of portions of the substrate (4) in the form of sheets, this storage operation succeeding the setting step and preceding an operation consisting of integrating said at least one module (2) into the body of a smart card (1), and during which storage operation at least one portion of the substrate (4), provided with the first conductive foil and the polymer material (13) comprising conductive particles, is positioned above or below another portion of the substrate (4), this other portion of the substrate (4) originating either from the substrate (4) wound onto itself, or from a sheet of substrate (4) placed above or below said at least one portion of the substrate (4), provided with the first conductive foil and the polymer material (13) comprising conductive particles, the polymer material (13) comprising conductive particles being configured by the setting step not to adhere to this other portion of the substrate (4) and to allow, by at least the application of pressure, the connection of said at least one module (2) to an antenna (10).

11. Interconnection method according to claim 10, wherein the connection is operated by applying a pressure comprised between 0.5 and 5 bars, with a thermode whose temperature is comprised between 170 and 210°C and for a time of less than 3 seconds.

12. Interconnection method according to claim 10 or 11, wherein the connection between the antenna (10) and the smart card module (2) of the smart card (1) is carried out by applying the polymer material (13) comprising conductive particles onto an end portion of the antenna (10) forming zigzags comprising tracks spaced from each other with a pitch of less than 250 micrometres.