Abstract:
A smart card has an electronic module and a card body carrying the module. The smart card includes a card body provided with a cavity and an electronic module having at least one portion presenting thickness that is less than the thickness of the card body. The electronic module is housed in the cavity and is secured to the card body. At least one through hole passes in succession through the portion of the module that presents a thickness that is less than the thickness of the card body, and through the card body.

Description:
[0001]    The invention relates to a smart card comprising a card body of plane shape carrying an electronic module. 
       BACKGROUND OF THE INVENTION 
       [0002]    In general, a smart card comprises a card body in the form of a plane card of plastics material having a rectangular outline, together with an electronic module carried by the body, the module comprising a processor associated with memory means, together with electrical contacts that are flush with one of the faces of the card body. 
         [0003]    Such a card is used in particular in applications that require a high level of security, such as for example applications of the bank payment card type. Such a card may also be used for constituting an identity badge, a transport ticket, etc., likewise implying a high degree of security. 
         [0004]    Various pieces of information are then printed on each face of the card body, this information generally including a hologram, a card number, etc. Furthermore, the data stored in the electronic module is protected by various digital encryption techniques. 
         [0005]    One known fraud consists in devising a pirate electronic module and in fastening it to a card body that has been used but that is authentic, so as to have a fraudulent bank card having the external appearance of a normal bank card. The fraudster can then hand the card over to a trader in order to make a payment, and the trader has no way of detecting that the electronic module carried by the card body is in fact a pirate module. 
         [0006]    Under such circumstances, the fraudster can make payments without being troubled by the traders to whom the card is shown or given in order to make those payments. 
         [0007]    Another fraud consists in using an authentic module with a card body that is fraudulent. The card body then carries the name of the pirate, but the chip in fact belongs to a bank card belonging to some other person, thus enabling the pirate to make purchases that are debited to the account of that other person. 
       OBJECT OF THE INVENTION 
       [0008]    The object of the invention is to propose a solution for remedying that drawback. 
       SUMMARY OF THE INVENTION 
       [0009]    To this end, the invention provides a smart card comprising a card body having a cavity and an electronic module having at least one portion presenting thickness that is less than the thickness of the card body, the electronic module being housed in the cavity and being secured to the card body, wherein the smart card includes at least one through hole that includes a portion passing through the portion of the module that presents a thickness that is less than the thickness of the card body, and a portion that passes through the card body. 
         [0010]    With this solution, it is difficult for a fraudster to make the holes in a used card body coincide with the holes in a pirate module. Each hole that passes light thus guarantees the authenticity of the association between the electronic module and the card body, and this authenticity can be verified merely by visual inspection. 
         [0011]    The invention also provides a smart card as defined above, wherein the module includes an electrical contact area and a unit including a processor associated with memory means, said unit being fitted to a central region of one of the faces of the electrical contact area, and wherein each through hole passes through a portion of the module corresponding to a peripheral region of the electrical contact area. 
         [0012]    The invention also provides a smart card as defined above, including a plurality of holes together defining one or more patterns. 
         [0013]    The invention also provides a smart card as defined above, including a first series of patterns relating to the manufacturer of the smart card and/or a second series of patterns specific to the particular smart card. 
         [0014]    The invention also provides a smart card as defined above, wherein each hole has a flared shape presenting a section of dimensions that increases from one end of the hole to the other. 
         [0015]    The invention also provides a smart card as defined above, including at least one flared hole of smaller-dimension section situated in a first face of the card, and at least one other flared hole having its smaller-dimension section situated in a second face of the card, said second face being opposite from the first face. 
         [0016]    The invention also provides a smart card as defined above, wherein each hole is made by laser perforation. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0017]      FIG. 1  is a side view in section of an electronic module for a smart card; 
           [0018]      FIG. 2  is a plan view of an electrical contact area of an electronic module for a smart card; 
           [0019]      FIG. 3  is a side view in section showing a smart card body and an electronic module before assembly; 
           [0020]      FIG. 4  is a side view in section showing a card body and an electronic module assembled together; 
           [0021]      FIG. 5  is a side view in section showing a card body and an electronic module assembled together after a through hole has been made; 
           [0022]      FIG. 6  is a side view in section showing a card body and an electronic module assembled together after two through holes have been made; 
           [0023]      FIG. 7  is a plan view showing a portion of the card body and an electronic module that are assembled together after two through holes have been made; and 
           [0024]      FIG. 8  is a plan view showing an electronic module assembled to a card body and in which a series of through holes have been made. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    As can be seen in  FIG. 1 , the electronic module  1  that constitutes the chip of a smart card comprises a unit  2  including in particular a processor and memory means embedded in protective means  3 , together with an electrical contact area  4  including a support film  6 . The unit  2  is fitted to a central region of one of the faces of the contact area  4 , and it is electrically connected to the contacts of the contact area  4 . 
         [0026]    As can be seen in  FIG. 2 , the contact area  4  has a rectangular outline with rounded corners and comprises two series of ten contacts or keys that are referenced  7  to  16 . These are contiguous and coplanar and each of them is in the form of a metal plate, with these contacts or keys being carried by the support film  6 . 
         [0027]    In the example of  FIG. 2 , the keys  7  to  10  and  13  to  16  are electrical contacts, whereas the keys  11  and  12  are not electrical contacts proper, insofar as they are not connected. The invention also applies equally well to a chip having an area with eight keys, as defined by the standard ISO 7816-2. 
         [0028]    The protective means  3  and the unit  2  are situated in a “bottom” portion  18  of the module  1 , whereas the contact area  4  and its support film  6  are situated in a “top” portion  19  that is superposed on the bottom portion  18 . 
         [0029]    As shown in  FIGS. 1 and 2 , the top portion  19  is of larger dimensions than the bottom portion  18  when these portions are looked at along an axis AX that is normal to the plane of the contact area  4 . 
         [0030]    Concerning their thicknesses, as measured along the axis AX, the thickness of the top portion  19  is less than the thickness of the bottom portion  18 , with the thickness of the module  1  as a whole being less than the thickness of the card body  21  in which the module  1  is to be fastened, as can be seen in particular for the smart card  20  that is shown after assembly in  FIG. 4 . 
         [0031]    The card body  21  typically comprises five layers that are superposed on one another, comprising a core layer, two printable layers situated on either side of the core layer, and two protective layers that are situated respectively on either side of the printable layers. The card body could equally well have some other number of layers. 
         [0032]    The module  1  is housed in a cavity  22  formed in one of the faces of the card body  21 , here the top face  23 , the module  1  being fastened to the card body  21 , e.g. by adhesive. This cavity  22  in this example is not a through hole and comprises a top portion  26  that is extended by a bottom portion  24  of smaller section. 
         [0033]    The top portion  26  is made for example by providing an opening in the top protective layer of the card, whereas the bottom portion  24  is made for example by milling. The top portion  26  of the cavity  22  has the same dimensions as the top portion  19  of the module  1 , and the bottom portion  24  of the cavity  22  has the same dimensions as the bottom portion  18  of the module  1 . 
         [0034]    Once in place, and as shown in  FIG. 4 , the module  1  is thus received in the cavity  22  by being engaged therein, with the contact area  4  then being situated flush with the top face  23  of the card body  21 , extending parallel thereto. 
         [0035]    In accordance with the invention, one or more through holes of small diameter, such as the through holes referenced  27  and  28  in  FIGS. 5 to 7 , are made after the module  1  has been secured to the card body  21 . They are situated in a portion of the module  1  that presents a thickness that is less than the thickness of the card body  21 , this portion here being a peripheral region of the top portion  19  in the example shown in the figures, i.e. a peripheral region of the contact area  4 . 
         [0036]    Each hole thus has a portion passing through a peripheral region of the contact area  4 , and a portion passing through the card body  21  in a region corresponding to the cavity  22 , and is a through hole so as to pass light. 
         [0037]    Given the functional clearances specified between the module  1  and the cavity  22 , there remains uncertainty as to the positioning of the module  1  relative to the cavity  22 , such that the fact that such a hole allows light to pass through means that the hole was very probably made after the module  1  and the card body  21  had been assembled together. 
         [0038]    In other words, these holes constitute an authentic physical link between the card body  21  and the module  1 . The fact that a hole passes light means that it was very probably made by the card manufacturer, thereby guaranteeing that the module  1  is indeed the module that was initially paired with the card body  21 . 
         [0039]    When a fraudster fastens a pirate module in an existing card body  21 , then assembling the pirate module and the card body  21  gives rise to an offset between the portion of the hole in the pirate module relative to the portion of the hole in the card body  21 , such that light can no longer pass through it. 
         [0040]    The sensitivity of this technique to that fraud is particularly large when the diameter of the through holes is selected to be small, thus making it possible to detect a positioning offset that is correspondingly small. 
         [0041]    These holes are advantageously made by laser perforation, giving them a frustoconical type flared shape, as can be seen in the section view of  FIG. 6 , with the diameters of these holes lying in the range fifty micrometers to three hundred micrometers. 
         [0042]    Each hole presents a smaller dimension section situated in the face of the card from which the hole was made, i.e. in the face of the card against which the laser was applied to make the hole. 
         [0043]    In order to take advantage of this frustoconical shape, a first series of holes such as the hole  27  is made from the bottom face  29  and another series of holes such as the hole  28  is made from the top face  23  of the card body  21 . 
         [0044]    Each hole of the first series, such as the hole  27 , has its smaller dimension section situated in the top face  23 . With this technique, a fraudster implanting a pirate module in an authentic card body will find it very difficult if not impossible to make a hole portion in the module that is in alignment with an existing hole portion in the authentic card body. 
         [0045]    In analogous manner, each hole in the second series, such as the hole  28 , has its smaller dimension section situated in the bottom face  29 . It is then almost impossible for a fraudster implanting an authentic module in a pirate card body to form a hole portion in the pirate card body that is in alignment with an existing hole portion in the authentic module. 
         [0046]    These series of holes may be made up of holes that are in positions that have been selected randomly. However, the holes formed in this way advantageously make up patterns or symbols such as letters of the alphabet, as shown in the example of  FIG. 8 , or indeed numerals. 
         [0047]    Under such circumstances, a first series of holes referenced  31  and made from the bottom face  29  defines five patterns referenced  32  to  36  and a second series of holes referenced  38  is made from the top face  23  and defines five other patterns referenced  39  to  43 . 
         [0048]    Advantageously, one of the series of patterns corresponds to the card manufacturer whereas the other series of patterns corresponds to the card itself, e.g. representing information that is also written on a face of the card body. 
         [0049]    In the example of  FIG. 8 , each pattern is formed by a set of holes, all of which are made in the same electrical contact. This thus makes it possible to write in readable manner a pattern or a symbol on each of the contacts, thereby making reading easier. 
         [0050]    A trader can thus verify the authenticity of the smart card merely by visual inspection. All that needs to be done is verify that the holes as formed in this way allow light to pass through, i.e., for example, that the symbols formed by these holes are visible when the card is placed in front of a light source. 
         [0051]    Advantageously, the symbols formed by the series of holes are also stored in the electronic module  1 , thus making it possible to perform an additional inspection, by verifying in the card reader that the image obtained by the reader illuminating the perforated zone does indeed correspond to the image recorded in the chip.