FR2862410A1 - Fabrication of a microcircuit card incorporating an identification mark to protect against the fraudulent extraction of the microcircuit - Google Patents

Abstract

The fabrication of a microcircuit card comprises producing a card body with a cavity emerging in an upper surface of this body and connecting to the wall of this cavity a module, incorporating a support film carrying a microcircuit on an internal surface, by means of a fixing material adhering to a part of this wall of the cavity and enrobing at least indirectly the microcircuit. The fabrication of a microcircuit card comprises producing a card body with a cavity emerging in an upper surface of this body and connecting to the wall of this cavity a module, incorporating a support film carrying a microcircuit on an internal surface, by means of a fixing material adhering to a part of this wall of the cavity and enrobing at least indirectly the microcircuit. Before connecting the module to the wall of the cavity a treatment of marking is applied in the immediate proximity of this part of the wall of the cavity to form a pattern detectable from the lower surface of the card body. Independent claims are also included for: (a) the microcircuit card thus fabricated; (b) a method for controlling of the microcircuit card.

Description

Field of the invention

  The invention relates to the securing of a microcircuit card in order to fight in particular against a type of fraud consisting in tearing the microcircuit from this card.

  As is known, a microcircuit card generally comprises a card body in which is formed a through cavity and a module formed of a support film carrying the microcircuit on an inner face of the support film; this support film is fixed in the card body in such a way that the microcircuit is located in the cavity. This microcircuit is in principle intended to cooperate with the outside by means of external contacts preferably carried by the outer face of the support film; but it can also be equipped with an antenna for data exchange without contact with the outside. In this case, given that the microcircuit can cooperate with the outside in two different ways, it is conventional to use the dual interface card designation (Dual Interface in English) or Combi card.

  It has already been proposed, in particular in the document WO-03/052822, to prevent the module from being inadvertently disassembled vis-à-vis the cavity, to treat the wall of this cavity so that it presents , with respect to a coating resin, an adhesion greater than that of the support film. Thus, when this coating resin is disposed in the cavity so as to coat the microcircuit by occupying a substantial portion of the volume between the support film and the wall of the cavity, this resin holds better to the wall of the cavity than to the support film so that an attempt to tear the microcircuit to the card body by action on the support film is limited to tearing of the support film.

  This solution, however, involves controlling the surface state of the wall (bottom and / or side wall) of the cavity and that of the support film depending on the nature of this wall and of this support film as well as that of a resin subsequently used for fixing the support film to the wall of the cavity.

  The object of the invention is to make it possible to secure the connection between the microcircuit and the wall of the cavity, without having to worry about the relative levels of adhesion of the support film and of this wall with respect to any coating resin.

  To this end, it proposes a method of manufacturing a microcircuit card according to which a card body is produced with a cavity opening into an upper face of this card body and a module is connected to the wall of this cavity, comprising a support film on a inner side a microcircuit, by means of a fastening material adhering to a portion of this wall of the cavity and at least indirectly coating the microcircuit, characterized in that, before connecting the module to the wall of the cavity, a marking treatment is carried out in the immediate vicinity of this part of the wall of the cavity so as to form there a detectable pattern from the lower face of this card body.

  The fixing material may be a resin that coats the microcircuit (so-called coating resin), but the invention also covers the case where the microcircuit is covered with a protective layer (called glob-top) before to be coated by the fastening material for attachment in the cavity.

  It is clear that this marking treatment can change locally, at the location of the pattern, the adhesion of the resin as is taught in the aforementioned document WO-03/052822, but it is important to note that the latter teaches a treatment affecting in principle a spread portion of this surface, without it being expected to form a detectable pattern from the underside of the card body.

  It will be appreciated that, when there is an attempt to tear the module of a microcircuit card according to the invention, the slightest detachment on the surface of the cavity will result in a significant deterioration of the pattern, which can be detected , even if the fraudster succeeds in implanting a new module in the card body. It is recalled that the resin is in principle chosen to be sufficiently adherent on the microcircuit not to be able to detach without seriously damaging the latter. It follows that a detachment of a module without destroying it can be done only if necessary at the level of the wall (bottom or side surface) of the cavity. Conversely, if the fraudster tries to insert the torn module into another card body, part of the original pattern would be detectable from the underside of the new card body; if this new card body was obtained from a card which was torn off the module, it would thus appear, from this lower face, two extracts of reasons a priori not compatible to detect fraud.

  According to preferred features of the invention, possibly combined: this marking treatment is carried out after making the cavity in the card body, possibly at the same time, if necessary, as a treatment of the adhesion this part of the wall of the cavity; it follows that this marking treatment easily integrates into the conventional method of manufacturing microcircuit cards, the step of producing the card body comprises a step of assembling a stack of layers to form the card body then a step of producing the cavity in this assembly, the marking treatment being carried out before the assembly step of the stack, on a layer to be located at the bottom of the cavity or under it; this gives all flexibility for the choice of the marking technology to be used, the step of producing the card body comprises a step of assembling a stack of layers to form the card body and a step of producing the cavity in this assembly, one of these layers being an inlay carrying tracks forming an antenna and having connection terminals intended to be electrically connected to the microcircuit; the invention thus applies without difficulty to the case of a card of the double interface type, - this marking treatment is such that the pattern appears in visible light by contrast vis-à-vis the bottom of the cavity as seen from the underside of the card body; this allows for example to a security officer carrying out the check of the card, if it is an identity card), to check itself the integrity of the card and thus to make sure of the This is why a particularly simple solution is that the marking treatment is carried out by forming a dark pattern on an opaque clear material; for this purpose, the card body advantageously comprises, between the cavity and the lower face, a material selected from the group consisting of PVC, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, or ABS.

  - Alternatively, the pattern can of course include colors.

  In another variant, the pattern can be read by a magnetic reader as described in the French patent application published under No. 2,838,543.

  to improve the visibility of the pattern, the thickness of the card body between the cavity and the lower face is at most equal to 300 microns, preferably at most equal to 200 microns; other types of detection are conceivable; thus, alternatively, the marking treatment is such that the pattern appears in infra-red or ultraviolet light, for example when using a visible ink with infra-red or ultraviolet, - in a particularly simple version, this marking treatment is performed on the surface of the bottom of the cavity, for example by means of an ink, - however, alternatively, this marking treatment reaches an intermediate level between the bottom of the cavity and the underside of the card body; preferably, this marking treatment is performed on a fraction of the thickness between the bottom of the cavity and the lower face of the card body; this guarantees good visibility and high stability of the pattern over time, - according to another variant, this marking treatment is performed by etching, which has the particular advantage of forming reliefs which will significantly increase the adhesion of the resin, which will further ensure that any attempt to tear the module will result in a deterioration of these reliefs and therefore the pattern, - as a particularly effective example, the marking treatment is achieved by local burning of a material forming the bottom of the cavity, - this marking treatment is performed by laser etching, so as to form recesses whose flanks are burnt, which combines the advantages of etching, and the formation of good contrasts vis-à-vis -vis the surrounding material, - the pattern can be of very varied natures, for example an alphanumeric sign (for example the name or a number of the wearer), and / or a bar code, and / or an image (for example a photograph, or a hologram, or a logo, etc ...), In a particularly advantageous manner, this method furthermore comprises a step during which the microcircuit of a piece of information is entered in a memory. identifying the reason, which will allow easy control of what the card available does not result from fraud.

  The invention further proposes, adapted to be obtained by the aforementioned method, a microcircuit card comprising a card body with a cavity opening into an upper face of this card body and, connected to the wall of this cavity, a module comprising a support film bearing on an inner face a microcircuit by means of a fastening material adhering to a part of this wall of the cavity and at least indirectly coating the microcircuit, characterized in that, in the immediate vicinity of this part of the wall of the cavity, is formed a detectable pattern from the underside of this card body.

  According to advantageous features of the invention, possibly combined (analogous to what has been said above about the method): the card body is formed of a stack of layers, one of which is an inlay carrying tracks forming an antenna and having connection terminals electrically connected to the microcircuit, - this pattern is detectable in visible light by contrast vis-à-vis the bottom of the cavity as seen from the underside of the card body, - this pattern is a dark contrasting pattern on an opaque clear material; alternatively, the pattern may of course have colors.

  in another variant, the pattern can be read by a magnetic reader as described in the French patent application published under No. 2,838,543; the card body comprises, between the cavity and the lower face, a chosen material; in the group consisting of PVC, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, and ABS.

  the thickness of the card body between the cavity and the lower face is at most equal to 300 microns, preferably at most 200 microns, alternatively, this pattern appears in infra-red or ultraviolet light, this pattern is produced on the surface of the bottom of the cavity, for example by means of an ink, - according to another variant, this marking treatment reaches an intermediate level between the bottom of the cavity and the lower face of the card body; this pattern is for example made on a fraction of the thickness between the bottom of the cavity and the lower face of the card body, - the pattern is made by etching, - the pattern is made by local burning of a material forming the bottom of the cavity, this pattern is made by laser etching and is formed of recesses whose sides are burned, - the pattern comprises an alphanumeric sign, and / or a barcode and / or an image such as a photo, a hologram or a logo, among others.

  In a particularly advantageous manner, the microcircuit comprises a memory containing information identifying the pattern.

  The invention also proposes a method of controlling a card of the aforementioned type, according to which the lower face of the card is observed until a pattern is detected opposite the location of the module.

  A particularly interesting case concerns the case where an identifier has been registered in the microcircuit; the invention then proposes a method of controlling such a card, characterized in that the pattern is detected, the information identifying the pattern is read and the compatibility between this pattern and this information is checked.

  It is recalled that this pattern can be inscribed for example on the bottom of the cavity or in an intermediate level between the bottom of the cavity and the underside of the card body.

Description of the invention

  Objects, features and advantages of the invention will become apparent from the description which follows, given by way of non-limiting indication with reference to the accompanying drawings in which: FIG. 1 is a cross-sectional view of the body of a card according to the invention; here of the double interface type, in a step of stacking layers to jointly form this card body, - Figure 2 is a cross-sectional view of this body in a subsequent manufacturing step, showing a cavity, the figure 3 is a schematic cross-sectional view of another microcircuit card according to the invention, here of the simple interface type, showing a pattern made at the bottom of the cavity, FIG. 4 is a top view of the front card body. the installation of the module of FIG. 3; FIG. 5 is a cross-sectional view according to an alternative embodiment of the card of FIG. 3; FIG. 6 is a view from above of another card, before putting in p Figure 7 is a view from below of the module, and Figure 8 is a cross-sectional view of another card according to yet another embodiment of the invention.

  Figures 1 and 2 show the preparation of a card body with a through-hole in an upper face of this card body. These figures are placed in the case of a dual interface type card, that is to say that an antenna is formed in the thickness of the card body, having connection terminals electrically connected to the module . In the example shown, the card body 10 comprises: an inlay 1, for example a PVC layer 200 microns thick carrying the antenna 2 formed of turns 3, for example copper, E two compensation layers 11 and 11 'surrounding this inlay, for example PVC or equivalent, capable in particular of absorbing the reliefs due to the presence of the antenna, E two printing layers 12 and 12' surrounding these compensation layers, intended to receive images or printed characters, and two cover layers 13 and 13 ', generally transparent.

  After stacking, these layers are assembled by any suitable known means, which will not be described here.

  The stacks of Figure 1 are in principle made for a network of cards, so that there is then, in practice, cutting individual card bodies.

  In FIG. 2, the stack of layers is assembled, and a cavity 15 has been formed, here with a peripheral step 16, onto which the connection terminals 3 of the antenna 2 open, and which delimits two zones 15A and 15B cavity.

  It is observed that the cavity here extends over more than half the thickness of the card body, so as to encroach here in the lower compensation layer.

  Figure 3 generally shows a portion of a card body 30, for example formed of a stack of layers similar to that of Figures 1 and 2, but having no antenna. But it should be understood that the following applies both to single-interface cards (with external contacts carried, usually by the module) that cards of the type with dual interface We see a module 20 formed of a support film 21 carrying on its underside a microcircuit 22. The latter is, in known manner, electrically connected to external contacts 23 and is mechanically fixed by its periphery by a fastening material 24. The module is furthermore fixed to a part of the wall of the cavity, here the bottom, by a fastening material 25 adhering to this wall and the module, preferably by coating at least indirectly the microcircuit.

  In the example shown, the fixing material 25 is a coating resin which coats the microcircuit.

  But in a variant not shown, this fixing material indirectly coats the microcircuit in that it adheres to another which encapsulates the microcircuit.

  According to the invention, before the module is connected to the wall of the cavity (referred to as an inserting operation), a marking treatment is carried out in the immediate vicinity of this part to which the fastening material adheres. to form a detectable pattern 60 from the underside of this card body.

  In the present case, this marking treatment is carried out after making the cavity, advantageously at the same time as a treatment of the adhesion of this part of the wall of the cavity, as proposed in document WO-03 / 05052822 above.

  In a preferred manner, the marking treatment is such that the pattern appears in visible light (thus under a light whose wavelengths are in the visible spectrum). However, it should be noted that, alternatively, this pattern may be detectable only under special conditions, for example in the case of infra-red or ultra-violet lighting.

  This pattern 60 is here schematized by black triangles pointing downwards. These black triangles schematize the fact that, preferably, the marking treatment is carried out by forming a dark pattern on an opaque clear material. Thus, between the bottom of the cavity and the bottom face, there is advantageously at least one material selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate or polycarbonate, or PVC.

  To facilitate the visual detection of the pattern, the thickness of the card body between the cavity and the inner face is at most equal to 300 microns, preferably not more than 200 microns.

  It may be noted that the card body is normally well pigmented, i.e. pigments are included in the material constituting at least some of the layers forming this card body, so that absence of cavity, the card body would be very opaque on all its surface. In practice, the materials conventionally used, such as those mentioned above, are opaque for thicknesses equal to that of the card body, or even equal to only its half.

  In a variant not shown, the marking treatment is performed before the assembly of the stack of layers, for example on the layer 11 'of the stack of FIGS. 1 and 2 since it is this layer which forms the bottom, when the cavity is formed. But this marking treatment can also be performed on a lower layer, that is to say in the immediate vicinity of the bottom of the cavity as in the example of Figure 3, but without reaching it.

  The marking treatment may be entirely located on the surface of the bottom of the cavity, for example made by means of an ink, visible to the naked eye or visible under infra-red or ultraviolet.

  However, preferably, this marking treatment reaches an intermediate level between the bottom of the cavity and the lower face of the card body. More specifically, here, the marking treatment is performed on a fraction of the thickness between the bottom of the cavity and the underside of the body of cade.

  Such a deep marking treatment could be achieved, chemically, by an ink penetrating into the material constituting this background. However, preferably, this treatment is performed by etching, that is to say with formation of reliefs that will enhance the adhesion of the fastening material 25 on the wall portion having this pattern.

  This etching is preferably performed by local burning of a material forming the bottom of the cavity.

  Thus, preferably, the marking treatment is carried out by laser etching, so as to form recesses whose flanks are burnt, that is to say which are sufficiently dark to form a good contrast vis- to the surrounding material.

  This laser engraving is for example performed with a pulsed laser which opens cones in the bottom of the card by sublimation of the plastic material that constitutes it. The diameter of these cones is typically of the order of 80 microns for a depth of 50 to 200 microns. The plastic is burned, so black, all around the cone, on maybe 10 microns, at the bottom but also on the flanks of these cones. It is this burnt plastic material, so black, which forms the drawing much more than the holes themselves.

  The thickness of the card body may be, in the example considered, of the order of 200 microns in the bottom of the cavity. When the marking treatment results in less visible marks, it may be useful to reduce this thickness below 300, even 200 microns, as was expressed above.

  It may be noted that the marking step can be performed simply by modifying the programming of existing machines. Thus it is possible to use a personalization machine, for example the one known under the name MPR5000 of DATACARD which is a personalization machine with an associated inserting module. It suffices to program this machine appropriately to obtain a step of marking the bottom before inserting.

  FIG. 4 shows a view from above of the cavity 26 of FIG. 3 before the module (inserting) is put in place. Note that the pattern 60 is here an alphanumeric sign formed of the batch indication and its number: this makes it possible to verify that this card bears a lot number compatible with the origin of the card in question. In this case, the pattern is common to all the cards of the batch In a variant, this pattern is a barcode or an image, such as a photo, a fingerprint, a hologram or a logo, in particular. In this case, the reason may be quite specific to the bearer, especially if it is an identity card, or its issuer (eg the company that made them). FIG. 5 shows a card body 50 similar to that of FIG. 3, except that the depressions associated with the marking treatment extend over the entire thickness of the card body between the bottom of the cavity and the lower face. of this card body. It is clear that the pattern 70 thus obtained is easily detectable since the contrast extends to the surface of the face by which the card body is observed.

  This configuration is particularly suitable in the case where the pattern is a barcode (although all types of patterns are likely to extend to the underside of the card body, since it depends on the technology chosen to achieve the marking.

  FIG. 6 represents a barcode pattern formed at the bottom of the cavity of the card body 50. This same pattern appears, upside down, on the rear or bottom face, represented in FIG. 7.

  It is easy, if the reason justifies it to be detected, to plan to mark the pattern upside down so that it appears in the place seen from the underside of the card body.

  The signs resembling 8 in Figure 6 are holes that are not detectable in Figure 7 if they do not open on the underside of the card body, or if the fastening material fills them correctly.

  This is shown diagrammatically in FIG. 8, where white projections are represented inside the dark triangles of the card body 50: these white projections represent fastening material having penetrated before curing in the hollows resulting from the marking, for example by laser engraving. This results in an anchoring effect of this fastening material which reinforces the connection between this material and the bottom of the cavity and increases the probability that an attempt to tear the module will result in a significant degradation of the pattern such as that it can be seen from the underside.

  In a particularly advantageous manner, it proceeds to the registration in the microcircuit, more specifically in a memory thereof referenced 100, information identifying the pattern.

  Thus, to verify the integrity of a card according to the invention, it is possible not only to check that a plausible pattern appears, of undegraded appearance, by the lower face, but that, moreover, when it has been detected this reason, this one is well compatible with the information serving as identifier. This identifier is for example the alphanumeric sign forming part of the pattern or a word evoking the image, etc.

  In the foregoing, it has been proposed that a material forming the card body between the bottom of the cavity and the bottom face is opaque. Of course, the invention also applies to at least partly transparent map-card cases, especially in their lower part.

  Similarly, it was assumed that the pattern was formed on the bottom (or under this bottom) of the cavity. But the invention is generalized in the case where the pattern is formed on a side wall of the cavity (it suffices to provide a sufficient contrast given the thickness of material between the material zone where the pattern is formed and the lower face of the map body.

  Even if the pattern is visible to the naked eye, it can be provided a reader to recognize it (especially in the case of a barcode).

  It will be appreciated that the invention contributes to graphically personalize a card by new marking means.

  This system of security customization can be used in all applications related to microcircuit cards, namely transport cards, bank cards, GSM cards, cards for pay television, etc ... but also in the field of identity ( passport, identity card, driving license, etc ...).

  It should be emphasized that laser engraving allows the formation of much finer patterns than the patterns conventionally obtained by the well-known technique of embossing, including the formation of large characters in the thickness of the card. By varying the fineness and the intensity of the laser beam, a wide variety of effects can be obtained which allow for a great personalization of the card, in particular thanks to the possibility of putting a lot of individual signs in the marking pattern.

  Of course, this pattern marking detectable from the underside of the card body combines without great difficulty known techniques for hardware security microcircuit cards.

Claims (49)

  1. A method of manufacturing a microcircuit card according to which a card body is produced with a cavity opening into an upper face of this card body and is connected to the wall of this cavity a module, comprising a support film bearing on an internal face a microcircuit, by means of a fastening material adhering to a portion of this wall of the cavity and at least indirectly coating the microcircuit, characterized in that, before connecting the module to the wall of the cavity, proceeds to a marking treatment in the immediate vicinity of this part of the wall of the cavity so as to form there a detectable pattern from the lower face of this card body.   2. Method according to claim 1, characterized in that this marking treatment is performed after making the cavity in the card body.   3. Method according to claim 2, characterized in that this treatment is performed at the same time as a treatment of the adhesion of this part of the wall of the cavity.   4. Method according to claim 1, characterized in that the step of producing the card body comprises a step of assembling a stack of layers (11-13, 11'-13 ') to form the card body and then a step of producing the cavity in this assembly, the marking treatment being performed before the step of assembling the stack, on a layer to be located at the bottom of the cavity or below it.   5. Method according to any one of claims 1 to 4, characterized in that the step of producing the card body comprises a step of assembling a stack of layers to form the card body and a step of realization of the cavity in this assembly, one of these layers being an inlay carrying tracks forming an antenna and having connection terminals intended to be electrically connected to the microcircuit.   6. Method according to any one of claims 1 to 5, characterized in that said marking treatment is such that the pattern appears in visible light in contrast vis-à-vis the bottom of the cavity as seen from the underside of the map body.   7. Method according to claim 6, characterized in that the marking treatment is carried out by forming a dark pattern on an opaque clear material.   8. The method of claim 7, characterized in that the card body comprises, between the cavity and the lower face, a material selected from the group consisting of PVC, polyethylene terephthalate, polybutylene terephthalate or polycarbonate.   9. The method of claim 7 or claim 8, characterized in that the thickness of the card body between the cavity and the lower face is at most equal to 300 microns.   10. The method of claim 9, characterized in that the thickness of the card body between the cavity and the lower face is at most equal to 200 microns.   11. Method according to any one of claims 1 to 5, characterized in that the marking treatment is such that the pattern appears in infrared or ultraviolet light.   12. Method according to any one of claims 1 to 11, characterized in that this marking treatment is performed on the surface of the bottom of the cavity.   13. The method of claim 12, characterized in that this marking treatment is performed by means of an ink.   14. Method according to any one of claims 1 to 11, characterized in that this marking treatment reaches an intermediate level between the bottom of the cavity and the underside of the card body.   15. The method of claim 14, characterized in that said marking treatment is performed on a fraction of the thickness between the bottom of the cavity and the underside of the card body.   16. The method of claim 15, characterized in that the marking treatment is performed by etching.   17. The method of claim 16, characterized in that the marking treatment is carried out by local burning of a material forming the bottom of the cavity.   18. The method of claim 17, characterized in that said marking treatment is performed by laser etching, so as to form depressions whose flanks are burned.   19. Method according to any one of claims 1 to 18, characterized in that the pattern comprises an alphanumeric sign.   20. Method according to any one of claims 1 to 19, characterized in that the pattern comprises a bar code.   21. Method according to any one of claims 1 to 20, characterized in that the pattern comprises an image.   22. The method of claim 21, characterized in that the image is a photo.   23. The method of claim 21, characterized in that the image is a hologram.   24. The method of claim 21, characterized in that the image is a logo.   25. Method according to any one of claims 1 to 24, characterized in that one proceeds to the registration in a memory of the microcircuit information identifying the pattern.   26. A microcircuit card comprising a card body with a cavity opening into an upper face of this card body and, connected to the wall of this cavity, a module comprising a support film on an inner face a microcircuit by means of a fixing material adhering to a portion of this wall of the cavity and at least indirectly coating the microcircuit, characterized in that, in the immediate vicinity of this part of the wall of the cavity, is formed a detectable pattern from the lower face of this card body.   27. Card according to claim 26, characterized in that the card body is formed of a stack of layers, one of which is an inlay carrying tracks forming an antenna and having connection terminals electrically connected to the microcircuit.   28. Card according to claim 26 or claim 27, characterized in that this pattern is detectable in visible light by contrast vis-àvis the bottom of the cavity as seen from the underside of the card body.   29. Card according to claim 28, characterized in that this pattern is a dark pattern contrasting on a light opaque material.   30. Card according to claim 29, characterized in that the card body comprises, between the cavity and the lower face, a material selected from the group consisting of PVC, polyethylene terephthalate, polybutylene terephthalate or polycarbonate.   31. Card according to claim 29 or claim 30, characterized in that the thickness of the card body between the cavity and the lower face is at most equal to 300 microns.   32. Card according to claim 31, characterized in that the thickness of the card body between the cavity and the lower face is at most equal to 200 microns.   33. Card according to claim 26 or claim 27, characterized in that this pattern appears in infra-red or ultraviolet light.   34. Card according to any one of claims 26 to 33, characterized in that this pattern is formed on the surface of the bottom of the cavity.   35. Card according to claim 34, characterized in that this pattern is produced by means of an ink.   36. Card according to any one of claims 26 to 33, characterized in that this marking treatment reaches an intermediate level between the bottom of the cavity and the underside of the card body.   37. The card of claim 36, characterized in that this pattern is made on a fraction of the thickness between the bottom of the cavity and the underside of the card body.   38. Card according to claim 37, characterized in that the pattern is made by etching.   39. The card of claim 38, characterized in that the pattern is achieved by local burning of a material forming the bottom of the cavity.   40. A card according to claim 39, characterized in that this pattern is made by laser etching and is formed of recesses whose sides are burned.   41. Card according to any one of claims 26 to 40, characterized in that the pattern comprises an alphanumeric sign.   42. Card according to any one of claims 26 to 41, characterized in that the pattern comprises a bar code.   43. Card according to any one of claims 26 to 42, characterized in that the pattern comprises an image.   44. Card according to claim 43, characterized in that the image is a photograph.   45. The card according to claim 43, characterized in that the image is a hologram.   46. Card according to claim 43, characterized in that the image is a logo.   47. Card according to any one of claims 26 to 46, characterized in that the microcircuit comprises a memory containing information identifying the pattern.   48. A method of controlling a card according to any one of claims 26 to 47, wherein the lower face of the card is observed until a pattern is detected opposite the location of the module.   49. A method of controlling a card according to claim 47, characterized in that the pattern is detected, the information identifying the pattern is read and the compatibility between this pattern and this information is checked.