Locally translucent contactless chip card incorporating a level-2 security element

Abstract

The invention relates to a communicating portable object (1) able to operate contactlessly, comprising a body into which is integrated a main antenna that is capable of receiving, via radio-frequency, electrical energy from an external reader and of communicating therewith, and an electronic module provided with a dielectric substrate bearing a microelectronic chip, characterized in that the dielectric substrate of the electronic module is made of a translucent material and comprises a region bearing an opaque security pattern, and in that the layers of the body arranged facing the security pattern are sufficiently translucent in the region of the electronic module to allow the security pattern (8) to be seen under external illumination directed towards the region of the security pattern.

Description

[0001] DESCRIPTION

[0002] Title: Locally translucent contactless smart card incorporating a level 2 security element

[0003] The invention relates to secure and communicating portable objects such as, in particular, chip identification cards or documents, provided with a contactless microelectronic module. The communicating portable object comprises an antenna integrated into the body of the portable object for communicating remotely with a radiofrequency reader.

[0004] By way of example and simplification of the description, the invention will be described in the context of its application to smart cards, without however limiting the scope of the invention to this form factor, the invention being applicable to other portable objects or to other form factors.

[0005] However, contactless smart cards produced in the standard format according to ISO 7810 constitute the most widespread example of identification cards to which the invention applies.

[0006] State of the art

[0007] For several years, a large number of contactless smart card designs have been available. A problem that regularly arises is counterfeiting, with fake cards copying the appearance of original cards issued by legitimate issuers being put on the market. Some of these smart cards have security patterns placed on the surface of the smart card. These patterns are clearly visible and can also be counterfeited.

[0008] Document US 2018 / 194158 A1 discloses a security document comprising an antenna and a chip connected to the antenna. This document also includes a transparent window located in front of a portion of the antenna, thus forming a security pattern of level 1 only, i.e. always visible to the naked eye.

[0009] Document US 2015 / 085285 A1 discloses a directional opacity watermark that can be seen through the front and back of a card by means of light-transmitting holes formed in a first optically opaque layer. The holes are partially filled with material from the optically transparent inner layer in order to transmit light through the light-transmitting holes. The card includes an electronic module but this is not provided with a translucent substrate, and no security pattern is provided on the module substrate.

[0010] WO 2010 / 007287 A1 describes a card having a multi-layer structure comprising a chip, a watermark and an antenna. The watermark can be observed in light transmitted through the structure, but it is not a level 2 security pattern arranged on a translucent substrate of an electronic module incorporated in a card body formed by a stack of layers whose light transmittance is adapted according to the transmittance of the module substrate, to ensure that the watermark is visible by contrast only under certain predefined lighting conditions.

[0011] It would therefore be useful to design a smart card with one or more security elements buried in the card body, or even in the electronic module itself, so as to be invisible to the naked eye in the absence of specific observation conditions. This therefore involves providing the smart card with a level 2 security element. This would strengthen the resistance of these cards to counterfeiting. Checking the presence or absence of security features is then made more complex and requires specialized equipment, especially since the card body and the electronic module are generally opaque to light.

[0012] Purpose of the invention

[0013] The general aim of the invention is therefore to propose a new structure for a portable communicating object with contactless operation, in particular a new structure for a smart card or equivalent, which is free from the above drawbacks, and in particular a structure allowing the discreet integration of a level 2 security pattern, forming part of the electronic module incorporated in the body of the smart card. This security pattern must therefore remain invisible under normal circumstances, but become visible under particular observation conditions, only on request, for example in the context of checks carried out by a law enforcement officer.

[0014] Another aim of the invention is to propose a new smart card structure making it possible to verify the existence of a security element using a simple visual check using a low-power lamp, such as that commonly available on mobile phones.

[0015] Another object of the invention is to propose a smart card structure which remains compatible with conventional and proven manufacturing processes, consisting of manufacturing an electronic module and a card body provided with a cavity, then transferring the module into the cavity of the card body.

[0016] Summary of the invention

[0017] In principle, the invention provides for adding a level 2 security element to the electronic module buried in the body of the smart card, using for the electronic module a translucent structure capable of receiving a security pattern visible on demand under a certain level of lighting. The degree of translucency of the module is adapted to that of the layers of the card body, to ensure that the security pattern of the module becomes visible by contrast only by subjecting the card to through-lighting, of a suitable power.

[0018] A level 2 security feature is defined as a feature with a security level higher than level 1, which implies a security feature directly visible to the naked eye, but lower than level 3, the detection of which requires sophisticated electronic equipment.

[0019] The invention implements the combined use of a translucent film for the substrate of the electronic module, and a specially adapted card structure in the area of ​​the electronic module to allow its examination in transmission (observation from the side opposite the light source) using a simple torch of the type commonly found as an accessory on mobile phones.

[0020] The invention therefore relates to a portable communicating object with contactless operation, comprising a body formed by a stack of different layers in which is integrated a main antenna capable of receiving by radio frequency electrical energy coming from an external reader and of communicating with the latter, and an electronic module provided with a dielectric substrate carrying a microelectronic chip, characterized in that the dielectric substrate of the electronic module is made of a translucent material and comprises an area carrying an opaque security pattern, said translucent material of the dielectric substrate of the electronic module having an optical transmission rate greater than 20% for light illumination wavelengths between 400 and 800 nm,and the stacking of the layers of said body and said dielectric substrate having an overall optical transmission rate of between 1% and 5% for light illumination wavelengths of between 400 and 800 nm, making it possible to view said security pattern only under external lighting of a minimum power of 50 lumens directed towards the area of ​​the security pattern from the face opposite the observation face.,

[0021] According to a preferred embodiment, the stack of layers of the body and the dielectric substrate has an overall optical transmission rate of approximately 3% for light illumination wavelengths between 400 and 800 nm.

[0022] According to one embodiment, said security pattern is a so-called level 2 security pattern, invisible under ambient lighting.

[0023] According to one embodiment, the dielectric substrate and the body are configured to have differentiated light transmission rates, so as to ensure the vision of the security pattern by contrast under the effect of external lighting.

[0024] According to one embodiment, the electronic module comprises a secondary antenna connected to the microelectronic chip and inductively coupled with the main antenna of the body.

[0025] According to an alternative embodiment, the electronic module comprises contact pads which are connected to the terminals of the main antenna of the body by wired galvanic connections or conductive vias.

[0026] According to one embodiment, the electronic module comprises a drop of transparent coating resin protecting the microelectronic chip, and said security pattern is produced on the translucent dielectric substrate, outside said drop of coating resin.

[0027] According to an alternative embodiment, said security pattern is produced on the translucent dielectric substrate, inside said drop of coating resin.

[0028] Preferably, the body comprises in its structure a white opaque layer 50 to 150 micrometers thick, and additional layers substantially transparent to visible light. According to one embodiment, said security pattern is a metallic pattern produced by chemical or laser etching from a metallic layer arranged on one face of the translucent dielectric substrate. Preferably, said metallic security pattern is produced on the same metallic layer as that forming an antenna of the electronic module.

[0029] According to one embodiment, the portable communicating object according to the invention is produced in the form of a smart card in the ISO 7810 standardized format.

[0030] Other characteristics and advantages of the invention will appear on reading the detailed description given in the application of the invention to a smart card, and the appended drawings in which:

[0031] - Figure 1 represents a plan view by transparency of a smart card according to the invention.

[0032] - Figure 2 represents a view along a section AA of the smart card of figure 1.

[0033] - Figure 3 represents a view along a section B-B of the smart card of figure 1 according to a first embodiment.

[0034] - Figure 4 represents a view along a section B-B of the smart card of figure 1 according to a second embodiment, and a view from below of the electronic module.

[0035] - Figure 5 shows an enlarged top view of the electronic module with its level 2 security pattern.

[0036] - Figure 6 represents a diagram of the procedure for controlling a smart card according to the invention.

[0037] - Figure 7 shows a curve of the transmittance of the smart card at the electronic module level, as a function of the wavelength.

[0038] Detailed description

[0039] Figure 1 shows a plan view by transparency of a smart card 1 according to the invention. This smart card 1 comprises a body (2) in which is integrated a main antenna (3) capable of receiving by radio frequency electrical energy coming from an external reader and of communicating with it, and an electronic module (4). In a known manner, the latter is provided with a dielectric substrate (5) carrying a microelectronic chip (6) (visible in Figure 3). In the schematic embodiment, the electronic module (4) itself comprises a module antenna (9) (visible in Figure 5) which can be electromagnetically coupled with the main antenna (3) of the card body (2).

[0040] Figure 2 schematically represents a sectional view of the smart card 1 along the section line AA of Figure 1. This sectional view shows the stacking of the different layers which constitute the card body 2. Thus, in the example shown, the card body 2 is composed of external layers 20, 21, 23 made of transparent plastic material, opaque layers 22, 24, and at least one layer 25 intended to be printed with an image personalized by the issuer of the smart card and visible from the outside.

[0041] As visible in Figure 3 which corresponds to a sectional view along the cutting line BB of Figure 1 and passing through the electronic module (4), a cavity (12) is arranged in the central layers of the card body, to receive the electronic module (4). This comprises a dielectric substrate (5) on one face of which is fixed a microelectronic chip (6) protected by a drop of coating resin (11).

[0042] According to the invention, the substrate (5) of the electronic module (4) is made of a translucent material and it comprises an area bearing an opaque security pattern (8). This may in particular be a metallic pattern, produced, in particular by etching, in the same metallic layer as that used to produce the antenna (9) of the module or to produce contact pads for the galvanic connection with the antenna (3) of the card body (2). In the embodiment of Figure 3, the security pattern (8) of the electronic module is arranged inside the coating drop (11).

[0043] In an alternative embodiment shown in Figure 4, the security pattern (8) is arranged outside the drop of coating resin (11).

[0044] It is important that the dielectric substrate (5) of the electronic module (4) is translucent, so that illumination directed towards the card in the area of ​​the electronic module (4) makes it possible to distinguish the opaque shape of the security pattern (8) through the substrate (5), as appears in more detail in Figure 5. A substrate (5) of the electronic module (4) having a light transmission rate of the order of 30% for visible wavelengths is a possible choice, whereas the epoxy glass substrates usually used for module substrates are generally much more opaque.

[0045] The layers (20, 21, 23) of the body (2) are chosen to be sufficiently translucent, with transmittances of the order of 80-85%, while the white layers (22, 24) are more opaque and only have a transmittance of the order of 10 to 20% (for light wavelengths between 400 and 800 nm) at least in the area of ​​the electronic module (4), to allow said security pattern (8) to be viewed under external lighting (13) directed towards the area (7) of the electronic module (4) in which the security pattern (8) is arranged.

[0046] Layers 20 to 24 are made of plastic material, preferably polycarbonate, but other materials such as PVC or PET can be used. These layers are consistent in thickness with the layers usually used for this type of card. Advantageously, at least one of these layers is customizable / markable by laser carbonization.

[0047] According to a tested embodiment, in the vicinity of the security pattern (8), the stack of all the layers of the card body including that of the substrate (5) of the module (4) may only have a transmittance of the order of 1% to 5% as shown in figure 7, while ensuring the visibility of the security pattern (8) under adequate lighting, for example a lamp (13) having a power of the order of 50 lumens. This type of lamp is very widespread, it is found in particular in mobile phones.

[0048] To verify the existence of a security pattern (8) within the smart card according to the invention, it is then sufficient for a controller (14) to proceed as shown diagrammatically in Figure 6, by means of a transmission examination, by sending the light flux from the lamp (13) onto one face of the smart card, while observing the opposite face. The opaque appearance of the security pattern (8) will be seen by contrast with the translucent substrate (5) and the transparent layers of the card body. The positions of the controller and the light flux can be swapped for this observation.

[0049] Advantages of the invention Ultimately, the invention allows a portable communicating object, in particular a smart card or an electronic passport, to achieve the intended goals.

[0050] In particular, the invention makes it possible to incorporate into the smart card a level 2 security pattern, invisible from the outside during normal use of the smart card, but the presence of which is simply detectable during a visual examination of the smart card using a simple moderate power flashlight.

[0051] The security pattern (8) can take a wide variety of forms, and it remains protected inside the smart card, out of reach of attempts at erasure or counterfeiting. Its production does not require an additional manufacturing step, since it can be etched into the metal layer of the antenna of the electronic module and produced at the same time as it. Checking for the presence of the security pattern (8) is not destructive.

[0052] Furthermore, the structure of the smart card according to the invention makes it possible to continue to use existing manufacturing processes and equipment, making it possible to form card bodies consisting of a stack of plastic layers and a cavity in which an electronic module is placed and fixed.

Claims

CLAIMS 1. A portable communicating object (1) with contactless operation, comprising a body (2) formed by a stack of different layers (20, 21, 22, 23, 24, 25) in which is integrated a main antenna (3) capable of receiving electrical energy by radio frequency from an external reader and of communicating with it, and an electronic module (4) provided with a dielectric substrate (5) carrying a microelectronic chip (6), characterized in that the dielectric substrate (5) of the electronic module (4) is made of a translucent material and comprises a zone (7) carrying an opaque security pattern (8), said translucent material of the dielectric substrate (5) of the electronic module (4) having an optical transmission rate greater than 20% for light illumination wavelengths between 400 and 800 nm, and the stack of layers of the body (2) and of the dielectric substrate (5) having an overall optical transmission rate between 1% and 5%,preferably approximately 3%, for light illumination wavelengths between 400 and 800 nm, making it possible to view said security pattern (8) only under external lighting (13) with a minimum power of 50 lumens directed towards the area (7) of the security pattern (8) from the face opposite the observation face., 2. Portable object according to claim 1, characterized in that the stack of layers of the body (2) and of the dielectric substrate (5) has an overall optical transmission rate of approximately 3% for light illumination wavelengths between 400 and 800 nm.

3. Portable communicating object (1) according to claim 1 or claim 2, characterized in that said security pattern (8) is a so-called level 2 security pattern, invisible under ambient lighting.

4. Portable communicating object (1) according to one of the preceding claims, characterized in that the dielectric substrate (5) of the electronic module (4) and the body (2) are configured so as to have differentiated light transmission rates, so as to ensure the vision of the security pattern (8) of the electronic module (4) by contrast under the effect of the external lighting (13).

5. Portable communicating object (1) according to any of the preceding claims, characterized in that the electronic module (4) comprises a secondary antenna (9) connected to the microelectronic chip (6) and inductively coupled with the main antenna (3) of the body (2).

6. Portable communicating object (1) according to one of claims 1 to 4, characterized in that the electronic module (4) comprises contact pads (10) which are connected to the terminals of the main antenna (3) of the body by wired galvanic connections or conductive vias.

7. Portable communicating object (1) according to any one of the preceding claims, characterized in that the electronic module (4) comprises a drop of transparent coating resin (11) protecting the microelectronic chip (6), and in that said security pattern (8) is produced on the translucent dielectric substrate (5), outside said drop of coating resin (11).

8. Portable communicating object (1) according to any one of claims 1 to 6, characterized in that the electronic module (4) comprises a drop of transparent coating resin (11) protecting the microelectronic chip (6), and in that said security pattern (8) is produced on the translucent dielectric substrate (5), inside said drop of coating resin (11).

9. Portable communicating object (1) according to any one of the preceding claims, characterized in that the body (2) comprises in its structure white opaque layers (22, 24) of 50 to 150 micrometers in thickness, and layers (20, 21, 23) substantially transparent to visible light.

10. Portable communicating object (1) according to any one of the preceding claims, characterized in that said security pattern (8) is a metallic pattern produced by chemical or laser etching from a metallic layer arranged on one face of the translucent dielectric substrate (5).

11. Portable communicating object (1) according to claim 10, characterized in that said metallic security pattern (8) is produced on the same metallic layer as that forming an antenna (9) of the electronic module (4).

12. Portable communicating object (1) according to any one of the preceding claims, characterized in that it is produced in the form of a chip card in the standardized ISO 7810 format.

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