Electronic module for smart card provided with a display screen, and its manufacturing method

Abstract

The invention relates to an electronic module (1) for a smart card, comprising a flexible printed circuit (2) having a rear face on which electronic components (4, 5, 6, 7) are fixed and a front face on which a display screen (3) is fixed, and said electronic module (1) comprising at least one protective layer (13a, 13b, 13c) for the display screen (3), characterized in that it comprises a spacer (14) surrounding the periphery of the display screen (3). Figure for the Abstract: Figure 1

Description

Title of the invention: Title Electronic module for smart card provided with a display screen, and its manufacturing method

[0001] The present invention relates to an electronic module for a smart card, its manufacturing method, as well as the smart card obtained after integration of this electronic module into a card body.

[0002] The electronic module according to the invention is particularly suitable for smart cards capable of displaying a dynamic security cryptogram called “dCVV”, an acronym for the English expression “dynamic Card Verification Value”. This smart card will then be called a “dynamic CW card” or more simply a “dCVV card”. STATE OF THE ART

[0003] A dCVV card is intended to further secure e-commerce transactions using a dynamic code and to improve the online shopping experience of users, compared to older cards simply provided with a fixed verification code known by the Anglo-Saxon expression "Card Verification Value", also noted CW, which is a fixed code printed on the body of the card.

[0004] Known dCVV cards have a 3-digit display integrated into the back of some standard credit cards. Instead of the conventional 3-digit static CW code printed on the chip card and which can be easily duplicated, this easy-to-use dynamic code solution prevents so-called "Card Not Present" fraud and is likely to give consumers, merchants and banks more confidence in their online transactions. For example, the so-called "eSecu" dynamic CW card is a conventional EMV contactless payment card that displays a dynamic value that automatically refreshes based on a time-varying One Time Password (OTP).

[0005] These known dCVV cards require the integration into the card body of a specific electronic module, for example such as that described in document WO 2021 / 206780 A1 (Ellipse) having both a contact terminal block on the front face, compliant with the ISO 7816 standard, and a screen on the rear face for displaying the dCVV code. This type of module, known as "all in one" or "all in one", has the advantage of integrating all the electronic components necessary for the operation of the smart card, in particular the microelectronic chip and its software application, in particular of the banking type, as well as the screen for displaying the dCVV code.

[0006] In principle, this architecture is therefore simple and makes it possible to integrate such a module with all the necessary electronic components in a cavity of the card body, without requiring the integration of discrete electronic components distributed on a printed circuit integrated into the card body.

[0007] However, this known architecture poses new technical problems in practice. A first problem that arises is to obtain a solution that allows the electronic module to be integrated and bonded into the machined cavity of the card body while maintaining sufficient transparency of the cavity bottom to allow good readability of the screen after its integration into the cavity of the card body. The screen located on the back of the electronic module must in fact be clearly visible at the back of the smart card, given that the front face of this electronic module is occupied by a contact terminal block.

[0008] Furthermore, the structure of the smart card must be compatible with the manufacturers' standard card manufacturing processes, in particular with the hot lamination phases of the card body layers.

[0009] Also known from document WO2021 / 091587 (Ellipse) is an electronic module comprising integrated electronic elements, and intended to be used in smart cards. The electronic module comprises a face provided with contacts intended to cooperate with the contacts of a smart card reader. The smart card also comprises a display screen, either on the electronic module itself, or arranged next to it on a face of the smart card. However, the electronic module described in this document does not itself comprise a screen protection layer, which does not make it possible to protect the screen during the handling phases before and during assembly of the module in a smart card body. Such protection would however be necessary, in particular against humidity, in particular when bistable screens such as electronic paper type screens must be used. PURPOSE OF THE INVENTION

[0010] The general aim of the invention is to propose a new structure of electronic module for contactless smart card, and a smart card provided with such a module, the front face of which has a display screen (also simply called a display), in particular for displaying a dynamic CW code, and which is capable of solving all of the technical problems mentioned above. By front face of the electronic module, we will designate the face of the module which remains visible after insertion of the module into the body of a smart card. The rear face of the module will then be the one which will be invisible after transfer of the module into the body of the smart card.

[0011] One of the main objectives of the invention is to propose an all-in-one module, comprising a display screen on the front face, and means for protecting this screen directly integrated into the module, which will allow it to be handled without risk before and during the smart card assembly phase.

[0012] The invention also aims to propose a method for manufacturing such an electronic module, and a smart card using such an electronic module. SUBJECT OF THE INVENTION

[0013] In principle, the invention consists of proposing an electronic module provided with a display on the front face and comprising protective layers for the display directly integrated into the electronic module. For this purpose, the front and rear faces of the display are protected by protective layers, in particular protection against humidity. Thus, the visible front face of the module's display is surmounted by a first protective layer forming part of the module, and intended to protect the display against humidity and other external aggressions such as ultraviolet radiation or shocks.

[0014] The rear face of the module screen, invisible from the outside of the smart card, will also be protected either by a protective layer similar to that of the front face, or by a copper layer.

[0015] The protective layers chosen will depend on the technology chosen for the display screen and its specific weaknesses.

[0016] Furthermore, the display screen will be surrounded on its periphery by a plastic spacer chosen to withstand the application of pressure and temperature during the steps of inserting the electronic module into a smart card body.

[0017] The invention therefore relates to an electronic module for a smart card, comprising a flexible printed circuit (also simply called "flex") having a rear face on which electronic components are fixed and a front face on which a display screen is fixed, and said electronic module comprising at least one layer for protecting the display screen, characterized in that it comprises a spacer surrounding the periphery of the display screen. This has the effect in particular of protecting the screen against the pressures and temperatures applied when inserting the module into a cavity of a smart card.

[0018] According to one embodiment, said display screen is an electronic paper type screen.

[0019] According to one embodiment, said at least one protective layer is a layer of protection against humidity, UV radiation, or shocks.

[0020] According to one embodiment, the electronic module comprises a first transparent protective layer located on the front face of the module and surmounting the display screen. This protective layer is made of a material such as polyimide or a PET treated to form a barrier against humidity.

[0021] According to one embodiment, said first protective layer has a three-dimensional shape and covers the upper face and the lateral edges of the display screen, and extends under said spacer.

[0022] Alternatively, said first protective layer has a flat shape and covers the entire front face of the electronic module, including the upper face of the spacer.

[0023] According to one embodiment, the module has a gap between the periphery of the display screen and the internal circumference of the spacer, this gap being filled with a filling material to avoid empty areas inside the electronic module likely to weaken the latter.

[0024] Preferably, the electronic module comprises a second protective layer located on the rear face of the module and integrated into the flexible printed circuit.

[0025] According to one embodiment, said flexible printed circuit of the module comprises two dielectric layers interposed with three metal layers interconnected by conductive vias, and said second protective layer is then constituted by a continuous portion of one of said metal layers of the flexible printed circuit.

[0026] Alternatively, the electronic module comprises a second protective layer located on the rear face of the module, made of a layer of polyimide or PET treated to form a moisture barrier, and this second protective layer extends under the display screen and under the spacer.

[0027] This second protective layer can be configured so as to encompass the entirety of said rear face of the module, including the passive electronic components.

[0028] The spacer preferably has a thickness corresponding to the thickness of the display screen. It is made of a plastic material chosen to withstand the pressure and temperature of the steps of fixing the electronic module in a smart card body. It is in particular made of PET or polyimide. The plastic spacer may be coated on its upper face with a thin metal layer, allowing heat to dissipate during the insertion of the module. This thin metal layer is optionally provided with a graphic personalization pattern.

[0029] The invention also relates to a method of manufacturing an electronic module as described above, characterized in that it comprises steps consisting of:

[0030] - Supply a flexible printed circuit having an upper face and a lower face and comprising a dielectric core and two metal layers arranged on either side around the dielectric core;

[0031] - Place a lower protective layer on the upper face of the circuit flexible print;

[0032] - Connecting a display screen above said lower protective layer with passive components located on the underside of the flexible printed circuit;

[0033] - Position a spacer around the display screen;

[0034] - Arrange a top protective layer over the display screen and the spacer;

[0035] - Laminate the different components together by hot lamination.

[0036] The invention also relates to a smart card comprising a card body formed by a stack of layers secured to each other, and a cavity intended to receive an electronic module, said cavity having a first peripheral zone of depth PI and a second central zone of depth P2 greater than PI, this smart card being characterized in that it comprises an electronic module as defined above. DETAILED DESCRIPTION

[0037] The invention will be described in more detail with the aid of the drawings, in which: - Figures 1 and 2 represent a first embodiment of an electronic module according to the invention, this module being represented respectively in sectional view ([Fig.l]) and in top view ([Fig.2]); - [Fig.3] represents a sectional view of a second embodiment of the electronic module according to the invention; - [Fig.4] represents a sectional view of a third embodiment of the electronic module according to the invention; - [Fig.5] represents a sectional view of a fourth embodiment of the electronic module according to the invention; - [Fig.6] represents a partial sectional view of a smart card incorporating an electronic module conforming to [Fig.3]; - [Fig.7] represents a partial sectional view of a smart card incorporating an electronic module conforming to [Fig.4].

[0038] Identical elements of the different embodiments described will be designated by the same numerical references.

[0039] Referring to [Fig.l]. The electronic module 1 comprises a flexible printed circuit 2, also called “flex” for simplification, on a front face of which is mounted a display screen or display 3 and on the rear face of which are mounted electronic components 4, 5, 6, 7. These comprise in particular, in a known manner, a secure identification component hosting the applications smart card software, a display driver circuit, and one or more passive components such as resistors or capacitors.

[0040] In the various embodiments of the module 1, the display 3 may be of different types. But it will preferably be a bistable display of the electronic paper type, also known as "papiel", or "e-paper" in English terminology. This type of display does not require backlighting and therefore no energy to leave a text or an image displayed after its power supply has been cut off. On the other hand, this type of display contains a gel which makes it sensitive to humidity. It is therefore particularly important that the module itself has an optimized structure to protect the display against any exposure to humidity, throughout the manufacturing cycle of the electronic module and the smart card which will receive it.

[0041] In order to solve this problem, the electronic module 1 according to the invention comprises protective layers directly integrated into its structure. This may be at least one transparent protective layer on the front face of the module, and preferably also a protective layer on the rear face of the electronic module.

[0042] According to one embodiment (figures 1, 3), the flexible printed circuit 2 comprises two dielectric layers 8 interposed with three metal layers 10a, 10b, 10c, in particular made of copper, interconnected by conductive vias 11, 12. A first protective layer 13a is arranged on the front face of the module, above the display 3, and a second protective layer 13b is arranged on the rear face of the module. In this case, this second protective layer 13b is constituted by a continuous part of one of said metal layers of the flexible printed circuit, namely a continuous part of the middle metal layer 10b. The middle metal layer 10b forms at the periphery of the module the turns of an antenna of the module, and in the central part of the module, it has a continuous zone forming a second protective layer 13b, intended to block the rise of humidity towards the display 3 from the rear face of the module.In the embodiment of [Fig.l], the electronic module 1 comprises a first transparent protective layer 13a covering the upper face of the display. This protective layer 13a is in particular made of transparent polyimide or other materials capable of constituting a barrier to humidity and UV radiation, such as a PET benefiting from treatment with an inorganic material, in particular mineral. This protective layer 13a has a thickness of a few micrometers, in particular approximately 50 micrometers.

[0043] The surface area of ​​the display 3 is smaller than the surface area of ​​the module 1, leaving a crown free around the display 3. In order to be able to apply the necessary temperatures and pressures to the module when it is inserted into a card body, chip, the electronic module 1 according to the invention further comprises a spacer 14 surrounding the periphery of the display 3. This spacer 14 is made of plastic, epoxy glass, polyimide or another material capable of withstanding the temperatures and pressures applied during the insertion of the module into a card body. The thickness of the spacer 14 is chosen so that the level of the upper face of the spacer 14 corresponds to the level of the upper face of the display 13. Furthermore, the thickness of the spacer 14 is an adjustment parameter making it possible to produce in a smart card a cavity whose depth PI (figures 6, 7) is adapted either for a galvanic connection or for a connection by inductive coupling with a concentrator antenna.The copper or aluminum antenna circuits are then preferably placed at the neutral fiber of the smart card, which limits bending stresses and increases the durability of the smart card.

[0044] In the embodiment shown in [Fig. 1], the first transparent protective layer 13a extends to the periphery of the electronic module 1, and the spacer 14 is arranged below the peripheral zone of the upper protective layer 13a, which reinforces the protection of the display 3 against possible infiltration of humidity from the front face of the module.

[0045] Preferably, in the embodiment of [Fig. 1], the gap between the periphery of the display 3 and the internal circumference 16 of the spacer 14 is filled with a filling material 17, for example a thermosetting resin or glue, making it possible to avoid empty areas inside the module and likely to weaken it.

[0046] Optionally, the electronic module 1 may comprise a thin metal layer 15 on the upper face of the spacer 14, to improve its resistance to mechanical friction and its external appearance. This metal layer 15 then preferably has an internal edge chamfered towards the transparent protective layer 13a, which makes it possible to improve the visual appearance of the module. This metal layer 15 may optionally be accompanied by a logo or a graphic personalization pattern.

[0047] In the embodiment shown in [Fig. 3], the upper transparent protective layer 13a is three-dimensional, instead of being flat as in [Fig. 1]. In this way, the transparent protective layer 13a surmounts the display 3, then folds back on the peripheral sides of the display 3 and passes in its periphery under the spacer 14. The spacer 14 can also be bi-material or bi-layer, for example with a metallic upper layer provided with an engraved pattern visible from the outside of the module.

[0048] According to another embodiment (figures 4, 5), the flexible printed circuit 2 comprises a single dielectric core 8 and only two metal layers 10a, 10b located on either side of the dielectric core 8 and interconnected with each other by conductive vias 11. The metal layers 10a and 10b are discontinuous because they are only used to make antenna turns or connections between the electronic components 4, 5, 6, 7 and the display 3. They are therefore devoid of a continuous part which could act as a rear protective layer of the display 3. In the case shown in [Fig. 4], the absence of a continuous metal layer is compensated either by a second flat protective layer 13b made of plastic material, in particular polyimide, directly integrated under the display screen. In this embodiment, the protective layer 13b is located directly under the display 3 and extends under the spacer 14.In this way, the display 3 is sandwiched between the two protective layers 13a, 13b made of plastic. In the case shown in [Fig.5], the absence of a continuous metal layer is compensated by a second three-dimensional protective layer 13c made of plastic integrated in the lower part of the electronic module and encompassing the passive components 4,5,6,7 of the module. The protective layers of plastic 13a, 13b, 13c are preferably surface-treated with an inorganic material to give them a very high level of insulation against humidity, necessary for e-paper technology screens.

[0049] The embodiment of figures 4 and 5 makes it possible to dispense with a flex 2 with three metal layers, so that the flex 2 is simplified, thinner and less expensive, since it now only comprises one dielectric layer 8 and two metal layers 10a, 10b.

[0050] [Fig. 6] represents a schematic view in partial section of a smart card 20 integrating an electronic module 1 according to [Fig. 1] or [Fig. 3], provided with a flex 2 with a double layer of dielectric 8 and three metal layers. Conventionally, the body of the smart card 20 comprises external layers 20a, 20b made of plastic, and an insert 21 provided with an antenna 22 of the card body allowing communication with an antenna of a remote reader (not shown). The card body 20a, 20b also comprises, in a known manner, a cavity 23 having a first zone of depth PI receiving the periphery of the electronic module 1, and a second zone of depth P2 greater than PI and receiving the central part of the module 1, thicker and provided with the electronic components 4, 5, 6, 7.

[0051] In the embodiment shown in [Fig.6], the electronic module 1 comprises an antenna 24 whose turns are positioned opposite certain turns of the antenna 22 of the card body, so as to be able to be electromagnetically coupled with them. The periphery of the lower face of the module 1 is fixed to the bottom of the PI depth cavity area by a heat-activated adhesive 25, of the “hotmelt” type in Anglo-Saxon terminology.

[0052] Despite the presence of the display 3 and the protective layers 13a, 13b, the structure of the module 1 is particularly thin, compatible with a cavity 23 of depth PI less than or equal to 320 micrometers and of depth P2 less than or equal to 620 micrometers.

[0053] The smart card 20 of [Fig. 7] comprises an electronic module 1 according to [Fig. 4], even thinner than that of figures 1 and 3, due to the use of a flex 2 with only two metal layers 10a, 10b, the display 3 of the module being protected on its front face by a first transparent protective layer 13a made of plastic, and on its rear face by a second protective layer 13b also made of plastic. The module 1 used in [Fig. 7] is without antenna, and is glued in the cavity 23 of the smart card 20 using an anisotropic adhesive 26, making it possible to establish a galvanic connection between the connections of the electronic components 4, 5, 6, 7 located on the metal layer of the flex, and the connections of the antenna 24 of the module.

[0054] In practice, the electronic modules 1 can therefore be designed to be compatible with an inductive, capacitive or direct connection with the communication device of the card body.

[0055] In a concrete embodiment, the protective layers 13a, 13b or 13c have a thickness of the order of 50 pm, the spacer 14 has a thickness of the order of 130 pm, the flex 2 with two metal layers has a thickness of the order of 90 pm, the flex 2 with three metal layers has a thickness of the order of 160 pm, the hotmelt adhesive 25 or the ACF 26 has a thickness of approximately 30 pm once pressed. The module 1 has a total thickness of approximately 600 pm. In total, the smart card 20 then has a typical thickness of 800 + / - 40 pm. ADVANTAGES OF THE INVENTION

[0056] The invention achieves the set objectives. In particular, it has the advantage of integrating a display screen in an easily readable manner into an electronic module, and of integrating means for protecting this screen directly onto the electronic module.

[0057] The display screen of the module allows in particular the display of a dCVV code on the visible surface of a smart card integrating such an electronic module. However, the invention is applicable to other types of smart cards and applications, provided that the smart card has a display screen.

[0058] The invention makes it possible to protect the module display well behind an upper protective layer located above the display and a lower protective layer located at the rear of the display. Thus the module display is well protected on both sides against external aggressions, in particular humidity, during the entire manufacturing cycle of the module and the smart card. This allows in particular the use of bistable displays of the e-paper type which are particularly thin and energy-saving, but sensitive to humidity.

[0059] The integration of the electronic module with its screen is particularly clean, without requiring buttons or other components in the card body or on its surface.

[0060] Ultimately, the solution according to the invention makes it possible to advantageously replace the dCVV cards which embed the screen and its control electronics on a PCB substrate located in the card body, away from the electronic module.

[0061] A smart card provided with a module according to the invention can be manufactured using a method using proven, reliable and economical techniques, including the machining of a cavity in the card body, then the transfer and gluing of the electronic module in the cavity.

[0062] The resulting smart card is fully compatible with the existing credit card system, easy to deploy on both the merchant and user sides.

Claims

Claims

1. Electronic module (1) for a smart card, comprising a flexible printed circuit (2) having a rear face on which electronic components (4, 5, 6, 7) are fixed and a front face on which a display screen (3) is fixed, and said electronic module (1) comprising at least one protective layer (13a, 13b, 13c) for the display screen (3), characterized in that it comprises a spacer (14) surrounding the periphery of the display screen (3).

2. Electronic module (1) according to claim 1, characterized in that said display screen (3) is an electronic paper type screen.

3. Electronic module (1) according to claim 1 or claim 2, characterized in that said at least one protective layer (13a, 13b, 13c) is a protective layer against humidity, UV radiation, or shocks.

4. Electronic module (1) according to claim 3, characterized in that it comprises a first transparent protective layer (13a) located on the front face of the module and surmounting the display screen (3), and made of a material chosen from polyimide or a PET treated to form a barrier against humidity.

5. Electronic module (1) according to claim 4, characterized in that said first protective layer (13a) has a three-dimensional shape and covers the upper face and the lateral edges of the display screen (3), and extends under said spacer (14).

6. Electronic module (1) according to claim 4, characterized in that said first protective layer (13a) has a flat shape and covers the entire front face of the electronic module (1).

7. Electronic module (1) according to claim 6, characterized in that it has a gap between the periphery of the display screen (3) and the internal circumference (16) of the spacer (14), this gap being filled with a filling material (17) to avoid empty areas inside the electronic module (1).

8. Electronic module (1) according to one of the preceding claims, characterized in that it comprises a second protective layer (13b) located on the rear face of the module and integrated into the flexible printed circuit (2).

9. Electronic module (1) according to claim 8, characterized in that said flexible printed circuit (2) comprises two dielectric layers (8) interposed with three metal layers (10a, 10b, 10c) interconnected by conductive vias (11, 12), and in that said second protective layer (13b) is constituted by a continuous portion of one (10b) of said metal layers of the flexible printed circuit (2).

10. Electronic module (1) according to one of claims 1 to 8, characterized in that it comprises a second protective layer (13b) located on the rear face of the module, produced by a layer of polyimide or PET treated to form a moisture barrier, and extending under the display screen (3) and under the spacer (14).

11. Electronic module (1) according to claim 10, characterized in that said second protective layer (13b) is configured so as to encompass the entirety of said rear face of the module, including the passive components (4, 5, 6, 7).

12. Electronic module (1) according to one of the preceding claims, characterized in that the spacer (14) has a thickness corresponding to the thickness of the display screen (3).

13. Electronic module (1) according to one of the preceding claims, characterized in that the spacer (14) is made of a plastic material chosen to withstand the pressure and temperature of the steps of fixing the electronic module (1) in a smart card body (20), in particular PET or polyimide.

14. Electronic module (1) according to claim 13, characterized in that the spacer (14) made of plastic material is coated on its upper face with a thin metallic layer (15), possibly provided with a graphic personalization pattern.

15. Method for manufacturing an electronic module (1) according to one of the preceding claims, characterized in that it comprises steps consisting of: - Providing a flexible printed circuit (2) having an upper face and a lower face and comprising a dielectric core (8) and two metal layers (10a, 10b) arranged around the dielectric core (8); - Arranging a lower protective layer (13b) on the upper face of the flexible printed circuit (2); - Connect a display screen (3) above the lower protective layer (13b) with passive components (4,5,6,7) located on the underside of the flexible printed circuit; - Position a spacer (14) around the display screen (3); - Arrange an upper protective layer (13a) above the display screen (3) and the spacer (14); - Laminate the different components together by hot lamination.

16. Smart card (1) comprising a card body (2) formed by a stack of layers (20a, 20b) integral with each other, and a cavity (23) intended to receive an electronic module (1), said cavity (23) having a first peripheral zone of depth PI and a second central zone of depth P2 greater than PI, characterized in that it comprises an electronic module (1) according to any one of the preceding claims 1 to 14.

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