Abstract:
A secured identification document has at least two flexible layers embedding an electronic module. The electronic module includes a flexible substrate on which are positioned an antenna and a radiofrequency microcontroller storing identification data. The radiofrequency microcontroller is electrically connected to said antenna. The secured identification document has the at least two flexible layers locally joined together by means of a chemically and mechanically tamper proof material that is applied in cavities that are distributed in each of said at least two flexible layers that surround the electronic module in order to make the electronic module interdependent with the at least two flexible layers.

Description:
BACKGROUND 
     The invention relates to secured identification documents and method for making them. More particularly, it relates to secured identification documents such as passports, made of paper booklets, or contactless smart cards or RFID tags, made of paper or plastic cards or tickets and which contain personal data of their holder such as his/her name, birth date, address, photograph, etc. 
     With the development of electronic identity documents, process have been implemented to include electronic devices, comprising an antenna and a radio frequency microcontroller electrically connected to said antenna, inside flexible document pages, flexible document covers, or flexible external layers of smart cards, in an efficient and robust way. 
     In  FIG. 1 , a prior art module  10  is embedded inside a pre-laminated inlet  12 . The module comprises an integrated circuit  11  affixed onto a support  13 . The integrated circuit and its connections are protected by a resin  14 . The support  13  has electrical pads  15  connected to the integrated circuit  11 . An antenna  16  is etched on a first plastic layer  12 A of the inlet. The antenna is connected to electrical contact pads  15 . Then a second plastic layer  12 B is laminated onto the first layer  12 A to create the inlet  12 . This second plastic layer  12 B recovers antenna  16  and module  10  in order to protect them physically. The inlet  12  is then affixed to a fibrous cover sheet  20  and an internal sheet  19  of a paper booklet constituting a passport for example. 
       FIGS. 2A and 2B , illustrate another embodiment of a prior art module, named “coil on module”, integrated in a cover sheet of a passport booklet ( FIG. 2A ) and in a contactless smart card ( FIG. 2B ). These structures and methods for manufacturing them have been implemented by the applicant. The “coil-on-module” means that the antenna  16  is part of the module itself and not part of a separate body like an inlet plastic sheet  12 A as in the first prior art embodiment of  FIG. 1 . The coil-on-module comprises a flexible substrate  30  on which is etched the antenna and is positioned a radio frequency microcontroller storing identification data, said radio frequency microcontroller being electrically connected to the antenna. 
     In the embodiment of  FIG. 2A , the coil on module is inserted in a multilayer arrangement, in which at least one layer  24 ,  25  has a cavity  23  incorporating the module  21 . Layers incorporating the module are then affixed onto the cover sheet  20  and internal sheet  19  by means of standard glue layers  22 , made of pressure sensitive glues or thermo sensitive glues. 
     In the embodiment of  FIG. 2B , the coil on module  10  is embedded between two external flexible layers  32 ,  33  of a smart card. For that, the module is either incorporated in a cavity of a spacer layer positioned between the two external layers  32 ,  33 , or embedded in a standard glue layer  22 . 
     In both mentioned product types, standard pressure sensitive adhesive such as acrylic glues, or standard thermo sensitive glues such as phenolic glues, are used in order to bond the module and the various other layers. 
     This results to a good-looking end device, which offer generally a good mechanically behaviour and a high resistance to delamination. 
     Nevertheless, the device keeps vulnerable against chemical products and particularly against solvent and acids. For example, after one hour soaked in acetone, the different layers can easily been separated without damage of the electronic component or of the external cover. 
     Thus, it appears easy to a fraudulent person to pull out the module from a passport or from an identification card, by delamination of the constitution layers, and to reuse this module in another falsified passport or identification device. 
     SUMMARY 
     Considering the above, a problem intended to be solved by the invention is to develop a secured identification document, comprising at least two flexible layers embedding an electronic module, said electronic module including a flexible substrate on which are positioned an antenna and a radiofrequency microcontroller storing identification data, said microcontroller being electrically connected to said antenna, said identification document being physically resistant against all type of attacks in order to avoid a fraudulent person pulling out the module from the identification document by delamination of the constitution layers. 
     In a first aspect, the solution of the invention to this problem consists in strongly embedding the electronic module and making it interdependent with the stack of said at least two flexible layers by means of a chemically and mechanically tamper proof material. 
     Advantageously, the chemically and mechanically tamper proof material is made of epoxy glue, UV activated glue, benzo-cyclo-butene glue or polyimide glue. 
     Such tamper proof material is very interesting because it is mechanically resistant and chemically resistant, more particularly solvent resistant. Its use make sure that the module is strongly embed in a stack of layers and cannot easily pulled out from the identification device by chemical attacks such as solvent or acid attacks for example. 
     In another embodiment the tamper proof material can also be made of plastic or metallic rivet. In such a case, rivets are not as flexible as the glues. Nevertheless, the use of rivet is interesting to affix the module on a layer, because a mechanical attack to pull out the module from an identification device can destroy the module by breaking the antenna and, in a better case, the silicon chip. 
     Another advantageous feature of the secured identification document according to the invention is: said at least two flexible layers comprise cavities filled with said chemically and mechanically tamper proof material in order to strongly stick the layers together and to embed the electronic module in the obtained stack of layers constituting the identification document. More particularly, each cavity of a first flexible layer is positioned above another cavity of a second layer in such a manner that cavities are piled up in the stack of said at least two layers. 
     These piles of cavities filled with the chemically and mechanically tamper proof material bring advantageously an external mark, or stamp, to prove authenticity and un-falsification of the identity document. 
     Correlatively, the solution of the invention relates to a method for making a secured identification document comprising at least two flexible layers embedding an electronic module, said electronic module including a flexible support on which are positioned an antenna and a radiofrequency microcontroller storing identification data, said microcontroller being electrically connected to said antenna, wherein said method comprises following steps:
         positioning said electronic module between said at least two flexible layers,   providing a chemically and mechanically tamper proof material to strongly embed the electronic module and make it interdependent with the stack of said at least two flexible layers.       

     For a better understanding of the present invention, reference will now be made, by way of examples, to the following description of the invention and to the accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1 , already described, is a schematic cross-section illustrating an identification document according to the prior art, 
         FIGS. 2A and 2B , already described, are schematic cross-section illustrating respectively a passport and an identification smart card of the prior art, 
         FIGS. 3A to 3C , are respectively an exploded cross-sectional view, a cross-sectional view, and a front view of a secured identification document according to a first embodiment of the invention, 
         FIGS. 4A to 4C , are respectively an exploded cross-sectional view, a cross-sectional view and a front view of a secured identification document according to a second embodiment of the invention, 
         FIG. 5  is a cross-sectional view of a secured identification document of a third embodiment of the invention, 
         FIGS. 6A and 6B  are respectively an exploded cross-sectional view and a cross-sectional view of a secured identification document according to a fourth embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Corresponding numerals and symbols in the figures refer to corresponding parts, unless otherwise indicated. 
     In a first embodiment of the invention,  FIGS. 3A to 3C , a contactless inlay  21 , which host an antenna and a silicon chip coated with resin, on one flexible substrate  30  is embedded between two flexible external layers  36  and  37 , made of fibrous material such as paper or paperboard, or of plastic. The illustrated identification document constitutes either a passport, such as a paper booklet, or a contactless identification smart card made of paper or of plastic. In this embodiment, several intermediate layers  32 - 35  are stacked in such a manner that they incorporate the module  21 . These layers  32 - 35  are made of paper, paperboard or of plastic. At least one layer  33 ,  34  of the stack of multilayer comprises a cavity  23  which surrounds at least partially the module  21 . 
     The different paper, polymer or textile layers  32 - 35  are provided with cavities  31  which are filled with mechanically and chemically tamper proof glue, in order to strongly stick these layers together and to make the module  21  interdependent with the stack of layers constituting the product. 
     Preferably, cavities  31  of a first layer  32  are positioned above corresponding cavities  31  of a lower layer  33 - 35 , in such a manner that cavities  31  are piled up in the stack of layers  32 - 35 . These piles of cavities form columns and are filled with the mechanically and chemically tamper proof material in order to stick the different layers  32 - 37  together and to embed very strongly the module  21  in the stack of layers. 
     Preferably, a layer  35  provided between the flexible substrate  30  of the module  21  and an external layer  36  comprises also at least one cavity  31  positioned below the flexible substrate  30  of the module, and filled with the tamper proof glue in order to affix very strongly the module onto the external layer  36 . 
     Advantageously, the mechanically and chemically tamper proof material is made of epoxy glue, UV activated glue, benzo-cyclo-butene glue or polyimide glue. These glues are mechanically resistant and they are resistant again chemical attacks, such as attacks made with solvents or acids. 
     More particularly, in addition to standard plastic or glue layers already selected for the encapsulation, such as pressure sensitive glues or thermo sensitive glues, specific solvent resistant glues are used to make certain that the coil on module stays interdependent with the external cover, and/or the intermediate paper or plastic layers. 
     A further advantage of the specific tamper proof glues relates to the cost per kg of these glues. Namely, some of the epoxy or UV glues are less expensive than some of the standard thermo sensitive glues or pressure sensitive glues which are already used for the encapsulation. 
     The tamper proof material can also be made of plastic or metallic rivet. 
     Thus, fraudulent attempts to pull out the module from the passport or the card, will result in a destruction of the different layers  32 - 37 , of the flexible substrate  30  of the module  21  and of the antenna. This can also result, in a better case, in the breakage of the radio frequency microcontroller. 
     Advantageously, cavities  31  are distributed on the whole surface of said layers  32 - 35 , as illustrated on the front view of  FIG. 3C . These cavities filled with the tamper proof material bring marks. These marks can be used to prove the authenticity and un-falsification of the identification document. Namely, if these marks become damaged, it means that a fraudulent person tried to pull out the module from the document by delamination of the layers. 
     These marks are apparent on the surface of the upper intermediate layer  32  and the lower intermediate layer  35  of the stack of layers  32 - 35 , when at least one flexible external layer  36  or  37  is delaminated. 
     In other embodiments, either at least one of the external layers  36 ,  37  can be made transparent in order to make these marks visible, or marks are directly apparent on at least one of the external layers  36 ,  37  which also comprise cavities  31 . 
     In a second embodiment of the invention,  FIGS. 4A to 4C , cavities  31  provided in the stack of layers  32 - 35 , and filled with the mechanically and chemically tamper proof glue, are positioned at the periphery of the identification document, namely at the periphery of the page of a passport booklet or at the periphery of the identification smart card. 
     An alternate solution to the above embodiments consists to replace the tamper proof glue placed between the module  21  and an external flexible layer  36 , by plastic or metallic rivets  39 . This third embodiment is illustrated in  FIG. 5 . The rivets  39  are specially placed in standard apertures, of the flexible substrate  30  of the module, which are provided close to its edges, and used to displace the substrate  30  during the manufacture of the modules, prior to their cutting off. Rivets  39  increase the adhesion of the module  21  to the external flexible layer  36  thus preventing fraudulent attempts to pull out the module from the passport or the identification smart card. Any attempts to pull out the module will result in the destruction of the support layer  30  of the module, of the antenna, and can also result, in better case, in the destruction of the radio frequency microcontroller. 
     More particularly, when the layers of the identification document are made of plastic, it is the case of a smart card for example, the use of an ultra-sonic welding cogwheel will allow a natural riveting of the module with the at least two plastic layers. An embodiment to manufacture those rivets  39  consists in an ultra-sonic welding of the plastic layers of the stack of layers against the module. The module  21  is placed between at least two plastic layers and an ultra-sonic cogwheel is moved along and on both sides of the plastic layers, in order to bond the plastic layers and more particularly to bond the module with the plastic layers. For that, the plastic layers are locally melted and the melted plastic fill in the standard apertures of the flexible substrate  30  of the module  21 . The module is then riveted inside the stack of plastic layers and impossible to remove without destruction. 
     In a further embodiment,  FIGS. 6A and 6B , the adhesion of the module  21  to the external flexible layers  36 ,  37  is improved by replacing acrylic or phenolic complete standard glue layers  26 , or intermediate layers  26  affixed with a conventional glue layer, by a solvent resistant glue layer  41  which is also mechanically resistant. 
     In general, the polymerization of the specific glue layers  41  or glue piles  31  is obtained by UV activation in oven or thermal activation in laminator. 
     Nevertheless, as such glues or resins are generally rigid, an alternative would be to limit them to a thin coating  41 , having a thickness of 20-40 μm, of the internal face of the textile or plastic external layer  36 . The coating can be done by wet spreading, such as silk screen printing, wet rolls, etc. . . . , or with specific sheet of acid and solvent resistant resin. Then the coil on module  21  is stick on it, and the rest of the assembly is done with standard glue layers. 
     An additional acid and solvent resistant resin  42  can also be provided to fill the cavity  23  made in at least one upper layer  26 , around the electronic module  21 , to also make it interdependent with the upper layers  26  and  37 . 
     The previous embodiments were described for a contactless identification document, such as a passport or an identification smart card. The invention is well adapted to all multilayer structures integrating an electronic device and where the product needs to be tamper resistant. Especially this is the case for the electronic passport and for contactless identification smart cards. However, it will be obvious for the person skilled in the art to accommodate the technology described hereby to other flexible devices comprising one or several modules or other electric or electronic components.