Abstract:
In a method for the production of a portable integrated circuit electronic device, an integrated circuit chip is transferred onto a dielectric support and connected to a metal grid comprising contact pads and connection pads. A housing is created for the chip on a metal grid by arching the grid. The dimensions of the housing enable the housing to accommodate the thickness of the card and the contact pads thereof. The grid is laminated on the dielectric support, whereby each contact pad of the card can be placed opposite to and in contact with the connection pads of the grid.

Description:
This disclosure is based upon French Application No. 99/06585, filed on May 25, 1999 and International Application No. PCT/FR00/01268, filed May 11, 2000, which was published on Nov. 30, 2000 in a language other than English, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to the manufacture of a portable electronic device including at least one integrated-circuit chip embedded in a support and electrically connected to interface elements consisting of a connection terminal block and/or an antenna. 
     These portable electronic devices constitute for example smart cards with and/or without contacts or electronic labels. 
     Smart cards with and/or without contacts are intended for performing various operations such as, for example, banking operations, telephone communications, various identification operations, or operations of the cash dispensing type. 
     Contact cards have metallisations flush with the surface of the card, disposed at a precise point on the card body, defined by the usual standard ISO 7816. These metallisations are intended to come into contact with a reading head of a reader with a view to an electrical transmission of data. 
     Contactless cards have an antenna for exchanging information with the outside by means of an electromagnetic coupling between the electronics of the card and a receiving appliance or reader. This coupling can be effected in read mode or in read/write mode, and the data transmission takes place by radio frequency or microwave. 
     There are also hybrid cards or “combicards” which have both metallisations flush with the surface of the card and an antenna embedded in the body of the card. This type of card can therefore exchange data with the outside either in contact mode or without contact. 
     As currently produced, the cards, with or without contact, are thin portable elements of standard dimensions. The standard ISO 7810 corresponds to a card with a standard format 85 mm long, 54 mm wide and 0.76 mm thick. 
     The majority of smart card manufacturing processes are based on the assembly of the integrated-circuit chip in a subassembly referred to as a micromodule which is connected to a communication interface and inset, that is to say placed in a cavity provided in a card body, using techniques known to experts. 
     A conventional manufacturing method is illustrated in FIG.  1 . Such a method consists in gluing an integrated-circuit chip  10 , disposing its active face with its contact pads  11  upwards, and gluing its opposite face to a dielectric support sheet  15 . The dielectric sheet  15  is itself disposed on a contact grid  18  such as a metallic plate made from nickel- and gold-plated copper for example. Connection wells  16  are formed in the dielectric sheet  15  in order to enable connection wires  17  to connect the contact pads  11  on the chip  10  to the contact areas on the grid  18 . 
     According to some variants, it is possible to glue the chip  10 , active face upwards, directly on the contact grid  18 , and then to connect it by hard wiring  17 . 
     In such a variant, the grid  18  is deposited on a dielectric support  15  and the contact connection areas on the said grid are defined by chemical etching or any other known means. 
     A protection or encapsulation step then protects the chip  10  and the soldered connection wires  17 . Use is generally made of a technique known as “glob top” in English terminology, which designates the coating of the chip from above. This technique consists in pouring a drop of resin  20 , based on epoxy for example, thermosetting or cross-linking under ultraviolet, on the chip  10  and its connection wires  17 . 
     FIG. 2 illustrates a variant embodiment in which the chip  10  is connected to the metallic grid  18  according to a “flip chips” method, which designates a known technique in which the chip is turned over. 
     In the example illustrated, the chip  10  is connected to the metallic grid  18  by means of a glue  350  with anisotropic electrical conduction which is well known and often used for mounting passive components on a surface. The output pads  11  on the chip  10  are placed opposite the connection areas on the grid  18 . This glue  350  in fact contains elastically deformable conductive particles which make it possible to establish electrical conduction along the z axis (that is to say along the thickness) when they are pressed between the output pads  11  and the connection areas on the grid  18 , whilst providing insulation in the other directions (x,y). 
     In a variant embodiment, the electrical connection between the chip  10  and the grid  18  can be improved by protrusions  12 , made from hot-melt alloy of the Sn/Pb type or conductive polymer, produced on the pads  11  on the chip  10 . 
     The dielectric support  15  with the chip  10  glued and protected by the resin  20  is cut in order to constitute a micromodule  100 . 
     In the case of a smart card with contact, the micromodule  100  is inset in the cavity in a previously decorated card body. This insetting operation can be effected by depositing a liquid glue in the cavity of the card body before attaching the micromodule. 
     FIG. 3 illustrates another insetting technique. The card body  110  is produced according to a conventional method, for example by injecting plastics material into a mould. The cavity  120  is obtained either by milling the card body, or by injection at the time of the manufacture of the card body in an adapted mould. 
     A heat-activated adhesive film  23  is deposited by hot lamination on the dielectric film  15  preferentially before the cutting out of the micromodule  100 . The latter is inset in the cavity  120  in the card body  110  and glued by reactivating the heat-activated adhesive  23  by hot pressing by means of a press  24  whose shape is adapted to that of the cavity  120 . 
     These known technologies for manufacturing contact cards have many drawbacks. 
     They require in fact a large number of operations. When protection by resin is effected, it is generally necessary to mill the resin in order to adapt its shape and thickness, which constitutes a tricky and expensive operation and one which places a stress on the chip. 
     In particular, the standard technology uses expensive techniques and a high-quality dielectric. The dielectric used is generally made from a glass epoxy composite or Kapton. 
     This is because the dielectric chosen must have properties of good resistance to temperature in order to be compatible with the insetting techniques described above. 
     In addition, the geometric definition of the different contacts and connection areas is generally obtained by chemical etching of the metallic grid deposited uniformly on the insulating support. However, chemical etching is an expensive operation. 
     In the case of a contactless smart card or an electronic label, the micromodule  100  is connected to an antenna  55 , as illustrated for example in FIG.  4 . 
     The antenna  55  is produced on an insulating support  52  consisting of PVC or PE or any other suitable material (polyvinyl chloride, polyethylene). 
     The antenna  55  is produced from a conductive material, in a coil, by screen printing with conductive ink, or by chemical etching of a metal deposited on an insulating support. It can have the shape of a spiral or any other pattern according to the required applications. 
     The chip  10  is glued and connected to connection areas on a metallic grid  18  by hard wiring  17  or according to any other known method, such as “flip chip” for example. 
     The chip  10  and its connection wires  16  are then protected by a resin  20  deposited according to the “glob top” technique described above, for example. 
     The connection between the antenna  55  and the metallic grid  18  can be effected by tin/lead soldering or by conductive gluing or lamination. 
     The body of the contactless card is then produced by hot lamination of plastic films in order to have the final thickness or by lining a resin between the two dielectric sheets  15  and  52  separated by a strut. 
     In the case of an electronic label, the antenna, in its definitive form, is chosen by moulding the body of the label around the electronics or by laminating plastic films or by inserting a plastic casing. 
     These known technologies for manufacturing contactless electronic devices have many drawbacks. 
     The disadvantages cited above for contactless cards are found again in the method of manufacturing contactless devices. 
     In addition, protecting the chip is tricky since effecting encapsulation is often impossible given the density of the module on the strip  52 , which obliges the manufacturer to effect an overmoulding of the micromodule. 
     SUMMARY OF THE INVENTION 
     The aim of the present invention is to mitigate the drawbacks of the prior art. 
     To this end, the present invention proposes a method for manufacturing an electronic device making it possible to use inexpensive materials and in particular a less expensive dielectric. 
     In addition, the invention simplifies the step of connecting the chip by producing a metallic grid which is arched so as to place the pads on the chip opposite the connection areas on the grid. 
     The object of the present invention is more particularly a method for manufacturing an integrated-circuit electronic device, an integrated-circuit chip being attached to a dielectric support and connected to a metallic grid having contact areas and connection areas, characterised in that it includes a step consisting of producing a chip housing on a metallic grid by arching of the latter, the said housing having dimensions making it possible to receive the thickness of the chip and its contact pads, and in that the said grid is laminated on the dielectric support so as to place each contact pad on the chip opposite and in connection with the said connection areas on the grid. 
     According to one characteristic of the invention, the dielectric support consists of a strip leaving the contact areas on the metallic grid free. 
     According to another characteristic of the invention, the metallic grid also has a second arch able to encase the thickness of the dielectric strip so as to place the latter flush with the contact areas on the metallic grid. 
     In a variant embodiment, the dielectric strip consists of a polyethylene terephthalate (PET). 
     In another variant embodiment, the dielectric strip consists of an acrylonitrile butadiene-styrene (ABS). 
     In another variant embodiment, the dielectric strip consists of paper. 
     In another variant, the dielectric strip ( 60 ) consists of a polyvinyl chloride (PVC). 
     According to one characteristic, the dielectric strip has an adhesive surface able to provide the gluing of the chip on the said strip. 
     According to one characteristic, reference holes and/or targets are produced on the dielectric strip so as to effect a precise gluing of the chip on the said strip. 
     According to a variant embodiment, the connection of the contact pads on the chip to the connection areas on the grille is effected by laser welding. 
     According to another variant embodiment, protrusions made from conductive polymer material are deposited on the contact pads on the chip, the connection of the said contact pads to the connection areas on the grille being effected by hot lamination. 
     According to a first application of the invention, the method includes a step of attaching the micromodule in the cavity of a card body. 
     The attaching of a micromodule is effected by activation of an adhesive film previously laminated over the entire surface of the metallic grid. 
     This adhesive film also constitutes an insulant providing the protection of the chip. 
     According to a second application of the invention, the method includes a step of connecting the micromodule to an antenna. 
     The chip is then protected by lamination of an insulating film over the entire surface of the metallic grid. 
     Advantageously, the insulation of the central turns of the antenna is provided by the dielectric strip. 
     The present invention also relates to an integrated-circuit electronic module, an integrated-circuit chip being attached to a dielectric support and connected to a communication interface having contact areas and connection areas, characterised in that the communication interface consists of an arched metallic grid, the arch defining a chip housing having dimensions making it possible to receive the thickness of the chip and its contact pads, and in that the connection areas on the grid are situated opposite and in connection with the contact pads on the chip. 
     According to one characteristic, the dielectric support consists of a strip leaving the contact areas free. 
     According to another characteristic, the metallic grid has two distinct arches, a first arch encasing the thickness of the chip and its contact pads, and a second arch encasing the thickness of the dielectric strip. 
     According to one characteristic, a protective film is laminated over the entire surface of the metallic grid. 
     The present invention applies to any portable integrated-circuit device such as smart cards or electronic labels, comprising an electronic module according to the invention. 
     The present invention makes it possible to obtain, with a simple and economical method, a thin electronic micromodule with good resistance to moisture. 
     In particular, the method according to the invention makes it possible to use a lower quality dielectric since the latter does not require the conventional properties of compatibility with the usual insetting techniques. 
     This is because, and this will emerge more precisely below, the dielectric does not cover the contact areas of the metallic grid. However, during insetting, it is these areas which are pressed or glued with a glue of the cyanoacrylate type. 
     The method according to the invention has the advantage of being able to be implemented in line without interruption. 
     In addition, the manufacturing method according to the invention has the advantage of considerably simplifying the connection of the chips to the connection areas on the grid. 
     In addition, the encapsulation and milling steps are completely eliminated, since the chip is protected by the grid and a film laminated over the entire surface of the grid. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other particularities and advantages of the invention will emerge from a reading of the following description given by way of illustrative and non-limitative example and made with reference to the accompanying figures, in which: 
     FIG. 1, already described, is a diagram in transverse section illustrating a traditional method for manufacturing a micromodule; 
     FIG. 2, already described, is a diagram in transverse section illustrating a traditional method for manufacturing a micromodule with a variant embodiment in the connection of the chip; 
     FIG. 3, already described, illustrates schematically the insetting of a micromodule according to a known method; 
     FIG. 4, already described, illustrates schematically the attachment of a micromodule to an antenna according to a known method; 
     FIG. 5 is a diagram in transverse section of a first embodiment of the manufacturing method according to the present invention; 
     FIG. 6 is a diagram in transverse section of a second embodiment of the manufacturing method according to the present invention; 
     FIG. 7 illustrates schematically the insetting of a micromodule according to the method of the invention; 
     FIG. 8 is a schematic view from below, on the assembly side, of the micromodule obtained by the method according to the invention; 
     FIG. 9 is a schematic view from above, on the contact side, of the micromodule obtained by the method according to the invention; 
     FIG. 10 is a schematic diagram of the steps of manufacturing a micromodule according to the invention; 
     FIG. 11 is a schematic plan view of a third embodiment of the manufacturing method according to the invention; 
     FIG. 12 is a diagram in transverse section of the attachment of a micromodule according to the invention to a screen-printed antenna. 
    
    
     DESCRIPTION OF THE INVENTION 
     FIGS. 5 and 6 illustrate first and second embodiments of a micromodule according to the invention. 
     These first two embodiments apply to smart cards with contact. 
     An integrated-circuit chip  10  is glued to a dielectric strip  60  laminated on a metallic grid  18  arched once or twice, a first time for encasing the thickness of the chip  10  and its contact pads  11  so as to put the connection areas  19   b  on the grid  18  opposite the contact pads  11  on the chip  10 , and a second time for encasing the thickness of the dielectric strip  60  so as to put the latter flush with the contact areas  19   a  on the grid  18 . 
     Preferentially, protrusions  12  have previously been produced on each contact pad  11  on the chip  10 . These protrusions  12  are intended to improve the electrical connection between the contact pads  11  on the chip  10  and their connection areas  19   b  on the grid  18 . They are consequently necessarily produced from a conductive material, such as for example gold, or from a polymer material loaded with metallic particles. 
     A protective film  25 , having cross-linking adhesive properties, is laminated over the entire surface of the grid  18 . This film  25  is not perforated, as was the case in the prior art, in order to leave the chip  10  and its connections free. 
     The manufacturing method according to the invention comprises at least the following steps. 
     These steps are illustrated schematically in the diagram in FIG.  10 . 
     A low-cost insulating material is cut into strips. This dielectric  60  can consist of PET (polyethylene terephthalate), PEN (polyethylene nerephthalate), paper, ABS (acrylonitrile-butadiene-styrene), PVC (polyvinyl chloride) or any other known low-cost insulating material. 
     The dielectric strip  60  can advantageously have a non-conductive adhesive face able to receive the gluing of the chip  10 . 
     When the dielectric  60  is cut out in a strip, reference holes to the pitch of the pattern (for example 9.5 mm) are produced in order subsequently to serve for the gluing of the chip  10  with precision. 
     According to the variant embodiments, the reference holes can be replaced by targets previously printed on the dielectric  60 . 
     The chip  10  is then glued to the dielectric  60  with precision to the pitch of the chosen pattern. 
     According to variants, the adhesive of the dielectric strip  60  is thermoactivated for gluing of the chip  10  hot, or is composed of a “tack”, which designates an adhesive at room temperature for gluing the chip  10  cold. 
     It is also possible to effect a deposition of glue on the dielectric  60  and to stick the chip  10  on this deposit of glue. 
     The precision of the gluing will be ensured by the referencing of the holes and/or targets previously produced on the dielectric strip  60 . 
     In parallel, a metallic grid  18  is produced based on a copper alloy for example, and covered with an electrolytic deposition adapted to the type of connection which it is wished to produce, for example gold or nickel. 
     According to one particularity of the invention, this grid  18  is arched once or twice according to conventional arching methods, by a punch for example. 
     In the variant embodiment illustrated in FIG. 5, the grid is arched twice. 
     A first arch  80  is intended to encase the height of the chip  10  and its protrusions  12  in order to place the connection areas  19   b  on the grid  11  and the protrusions  12  opposite each other. 
     A second arch  81  is intended to encase the step on the dielectric strip  60  so as to obtain a micromodule  100  which is perfectly flat on the contact  19   a  side. Thus the dielectric  60  is flush with the contact areas  19   a  on the grid  18  whilst leaving them free so as to provide communication from the circuit towards the outside. 
     The variant embodiment illustrated in FIG. 6 has only the first arch  80 . 
     The grid  18  and the dielectric  60  are then laminated. 
     The second arch  81  facilitates the lamination of the dielectric  60  on the grid  18  whilst forming a guide for the dielectric strip  60 . 
     The lamination, carried out by means of the references on the dielectric strip  60  and/or by means of the second arch  81 , put the connecting areas at  19   b  on the grid  18  opposite the contact pads  11  possibly provided with protrusions  12  on the chip  10 . 
     It should be noted that, the chip  10  being connected below the grid  18 , the contact areas  19   a  on the grid  18  will be directly in correspondence, via the connection areas  19   b , with the pads  11  on the chip  10 . Consequently the problem of having to produce an adapted and complex pattern, as is the case in the connections according to the “flip chip” methods described above, will not be posed. 
     It is then necessary to effect the connections of the pads  11  on the chip  10  to the connection areas  19   b  on the grid  18 . 
     To this end, different known methods can be used, such as for example laser welding methods, or deposition of an anisotropic adhesive or a thermocompression method, or by activation of the conductive polymer protrusions previously deposited on the contact pads  11  on the chip  10 . 
     It is advantageous, as already disclosed with reference to the prior art, to laminate an adhesive  25  which can be reactivated by heat or pressure over the entire useful surface of the grid  18 . 
     Advantageously, the adhesive  25  has insulating properties in order to constitute additional protection for the chip  10 . This is because the adhesive  25  is not perforated as was routinely the case in the prior art. 
     Depositing a protective resin on the chip  10  can therefore be completely excluded in this manufacturing method. 
     The micromodule  100  is then cut out by means of a punch or a laser beam, and then fitted in the cavity of a card body by reactivating the adhesive  25  or depositing a drop of glue of the cyanoacrylate type, for example, in the cavity. 
     FIG. 7 illustrates the step of insetting the micromodule  100  in the cavity  120  of the card body  100 , by the technique of hot pressing in order to reactivate the adhesive  25 . 
     This figure shows clearly that hot pressing is not applied to the dielectric  60 , but solely to the metallic grid  18 , the punch  24  having a recess corresponding to the dielectric  60 . 
     Likewise, if a technique of attachment with a glue of the cyanoacrylate type had been chosen, the glue would have been applied between the cavity  120  of the card body  100  and the metallic grid  18  covered or not with the adhesive  25 , and not on the dielectric  60 . 
     FIGS. 8 and 9 illustrate respectively schematic views from below and above of the micromodule obtained by the method according to the invention applied to contact cards. 
     FIGS. 5 and 6 are sections A—A of FIG.  8 . 
     FIG. 8 shows clearly the arches  80  and  81  on the metallic grid  18 , the first delimiting the contact areas  19   a  and the connection areas  19   b , and the second possibly delimiting the zone of the dielectric strip  60 . 
     FIG. 9 shows the external side of the micromodule, on the ISO contacts side. 
     According to one of the variants, disclosed previously, the dielectric strip  60  is flush with the contact areas  19   a  on the metallic grid  18 . The outside of the smart card thus obtained is therefore perfectly flat. 
     In the other variant, the dielectric strip  60  will form a small step on the top of the contact areas  19   a.    
     In addition, the connection terminal block  18  on the chip card obtained has a middle zone corresponding to the dielectric strip  60  on which a logo or drawing can be printed (preferentially directly at the time of cutting out of the insulating material in strip form). This face of the dielectric strip  60  can possibly be in different colours and/or carry the serial number of the card. 
     FIGS. 11 and 12 illustrate a third embodiment of a micromodule according to the invention which applies to contactless cards or electronic labels. 
     FIGS. 11 and 12 illustrate respectively a plan view and a view in transverse section of the manufacturing method according to this third embodiment of the invention. 
     The method described previously for contact cards is repeated, the operation of laminating the arched grille  18  on the dielectric  60  being all the easier since the number of contact pads  18  on the chip  10 , with or without protrusion  12 , to be connected to the connection areas  19   b , is only two. 
     Moreover, protection of the chip  10  is obtained by laminating a solid film  26  over the entire surface of the micromodule  100 . All the problems of the prior art related to the deposition of a drop of resin for protection by encapsulation or overmoulding are therefore avoided. 
     In addition, as illustrated in FIG. 11, it is possible, in the context of this application, to laminate as many dielectric strips  60  as possible in order to optimise the number of micromodules on a grid  18 . 
     FIG. 12 illustrates the connection of the micromodule  100  with an antenna  50 , carried out according to standard techniques. 
     Advantageously, the dielectric  60  can serve to isolate the contacts  55  from the other turns on the antenna  50 , in the case of a screen-printed antenna. This makes it possible to avoid the screen printing of an insulant on the central turns.