FR2785071A1 - Method for manufacturing contactless IC with internal aerial by using adhesive current conducting foil on contact pads for making contact with antenna and fixing chip - Google Patents

Abstract

An electronic module (M) is inserted into a cavity (110). Contact pads (170) covered by an electrically conducting foil (130), located on a side of the chip facing the cavity, provides an electric connection between the electronic module (M) and terminals (125) of an antenna (120) for fixing the module (M). An Independent claim is included for: (a) a process of manufacture of double-sided micro-module

Description

METHOD FOR MANUFACTURING A CHIP CARD AND A
ELECTRONIC MODULE FOR INSERTION INTO A
SUCH CARD.

 The present invention relates to the manufacture of smart cards, and more particularly of cards capable of ensuring a contact operating mode and a contactless operating mode. This type of card will be called, in the rest of the description, mixed-operation cards, or mixed chip card.

This type of card has an antenna integrated in the card body and a double-sided micromodule connected to the antenna. The invention also relates to a method of manufacturing this double-sided micromodule.

 With mixed-operation cards, the exchange of information with the outside is done either by the antenna which provides electromagnetic coupling between the card's electronics and a reader (contactless operation), or by the contacts flush with the surface of the card which ensures an electrical transmission of data when they are in contact with a read head of a reader (operation with contacts).

 The invention is not limited only to. mixed cards. It also relates to contactless smart cards, that is to say smart cards capable of ensuring only contactless operation, the exchange of information to the outside being done only by the antenna. However, to simplify the presentation of the invention, we will only speak, in the following, of mixed cards, the manufacturing process extending, as has just been said, also to contactless smart cards.

 Such cards with mixed operation, or with contactless operation, are intended to perform various operations such as, for example, banking operations, telephone communications, various identification operations, debit operations or reloading of credit units. account, and all kinds of operations which can be carried out either by inserting the card in a reader, or remotely by electromagnetic coupling (in principle of inductive type) between a transmission-reception terminal and a card placed in a zone of action of this terminal.

 Mixed smart cards must have standardized dimensions identical to those of conventional smart cards with contacts. This is desirable for cards operating only contactless. The dimensions of these cards are defined by the usual standard ISO 7810 which corresponds to a standard format card 85 mm long, 54 mm wide and 0.76 mm thick.

 These standards impose severe constraints for manufacturing. The very small thickness of the card is in particular a major constraint, even more severe for mixed cards than for cards simply provided with contacts, since it is necessary to provide for the incorporation of an antenna in the card.

 The main technical problems which arise are problems of positioning the antenna relative to the card, since the antenna occupies almost the entire surface of the card, problems of positioning of the integrated circuit module (comprising the chip and its contacts) which ensures the electronic functioning of the card and the problems of precision and reliability of the connection between the module and the antenna. The constraints of mechanical strength, reliability and manufacturing cost must also be taken into account.

 The antenna generally consists of a conductive element deposited in a thin layer on a plastic support sheet. Connection terminals are provided at the ends of the antenna which must be updated in order to be able to connect them to the contact pads of the electronic module.

 The conductive element forming the antenna will hereinafter be referred to as antenna wire, since, depending on the technology used, it may be either an embedded or laminated wire on a manufacturing support sheet, or conductive tracks printed on this support sheet.

 A solution envisaged for manufacturing these mixed chips is illustrated in FIGS. 1A to 1C.

This solution consists firstly in producing, on a support sheet 10, an antenna 11 whose turns are placed outside the connection terminals 12, an insulating bridge making it possible to connect each of the ends of the antenna respectively to a antenna connection range. In a second step, the sheet 10 supporting the antenna wire 11 thus produced is assembled with other plastic sheets 20, 30, 40, 50 to form the card body. This card body is then machined so as to form on the one hand a cavity 61 reserved for a double-sided electronic module M and located between the connection terminals 12 of the antenna 11, and on the other hand connection wells 62 intended to update the connection terminals 12 of the antenna 11. The connection wells 62 are then filled with an electrically conductive substance which provides the electrical connection between the antenna and contact pads 72 of the electronic module M.

 However, this solution is still relatively expensive. Indeed, the specific step of machining the connection wells, to make up for the antenna connection terminals, contributes to obtaining a relatively high manufacturing cost. In addition, filling the connection wells with an electrically conductive substance, to make the electrical connection between the module and the antenna, is a delicate operation to carry out which tends to result in a reduction in the production yield and, by Consequently, an increase in the cost price. Finally, good quality adhesion between the electronic module and the electrically conductive substance is relatively difficult to obtain, so that the electrical connection between the module and the antenna is not always reliable, which implies that a large number of cards is still intended for scrap. This high number of cards intended for scrap also contributes to increasing the cost price of the cards.

 Since mixed smart cards are intended to be manufactured in very large quantities, in order to be distributed to the general public, it is necessary to be able to reduce their manufacturing cost as much as possible. An object of the present invention therefore consists in eliminating the most expensive specific steps, that is to say in particular the machining of the connection wells and the dispensing of an electrically conductive substance in these wells.

For this, the invention provides a method of manufacturing a smart card, said smart card comprising a card body obtained by assembling sheets of superimposed plastic material by enclosing, in the superposition, an antenna at the ends of which are provided for connection terminals to an electronic module, characterized in that it comprises the following steps:
supply of a card body comprising an open cavity, said cavity comprising at least one flat bottom, and said antenna connection terminals being updated in the cavity substantially at said flat bottom,
-report of the electronic module in the cavity, said module comprising on its underside, turned towards the inside of the cavity, contact pads covered by a sheet of electrically conductive adhesive capable of simultaneously ensuring an electrical connection, between the pads contact module and antenna connection terminals, and a fixing of said electronic module.

 According to another characteristic of the invention, the cavity is obtained by machining an opening in the card body, in which the antenna and its connection terminals are embedded.

 According to another characteristic of the invention, the cavity is obtained by laminating several sheets comprising perforations corresponding to the cavity.

 According to another characteristic of the invention, the antenna comprises at least two turns which are produced outside of its connection terminals.

 According to another characteristic of the invention, the sheet of electrically conductive adhesive, covering the contact areas reserved for the electrical connection with the antenna connection terminals, comprises on the one hand a central hole provided for accommodating a integrated circuit chip; and on the other hand two notches located respectively between the locations reserved for the contact pads, in order to separate said adhesive sheet into two zones electrically isolated from one another.

 According to yet another characteristic of the invention, the two notches made in the sheet of electrically conductive adhesive are diametrically opposite.

 Thanks to this manufacturing process, the specific and costly steps of machining connection wells and dispensing conductive substance have been eliminated. The method according to the invention therefore makes it possible to achieve a financial gain. In addition, the sheet of electrically conductive adhesive, placed on the contact pads of the underside of the electronic module, simultaneously makes it possible to fix the module and to produce a highly reliable electrical interconnection between the module and the antenna. As a result, the number of cards destined for scrap is considerably reduced.

 Another object of the invention relates to a method of manufacturing an electronic module intended to be inserted into this smart card. The electronic module can be single sided. In this case, it makes it possible to produce a smart card operating only without contact. It can also be double-sided to allow the production of a mixed card.

The method of manufacturing such a double-sided electronic module consists firstly in producing, on an upper face of an insulating film, first contact pads intended to serve as access contacts for the smart card and, on a lower face of said insulating film, second contact pads intended to be connected to the connection terminals of the antenna. In a second step, an integrated circuit chip is bonded to the underside of said insulating film and electrical connections are made between the chip and the first and second contact pads respectively. The chip and the electrical connections are then encapsulated in a protective resin. The method is more particularly characterized by the fact that it further comprises the following steps:
applying an electrically conductive adhesive film to the underside of the insulating film, so that it covers the second contact pads, said adhesive film comprising on the one hand a central hole for accommodating the encapsulated integrated circuit chip therein; and on the other hand two notches located respectively between the locations reserved for the second contact pads, then
-cut the assembly thus formed at least flush with the notches, so that the latter make it possible to separate the adhesive film into two zones electrically isolated from one another and situated respectively on one of the second ranges of contact.

 According to another characteristic of this process, the electrically conductive adhesive film is applied to the insulating film by hot lamination.

Other particularities and advantages of the present invention will appear on reading the description given by way of illustrative example, and without limitation and made with reference to the appended figures which represent:
FIGS. 1A to 1C, already described, sectional views of a chip card with mixed operation during the stages of manufacturing of a method envisaged previously,
FIGS. 2A and 2B, two sectional views of two alternative embodiments of a mixed chip card manufactured according to the invention,
FIG. 3, a top view of a mixed smart card according to the invention, during its manufacture,
FIGS. 4 and 5, bottom views of an insulating film during the continuous production of electronic modules,
FIG. 6, a bottom view of an electronic module according to the invention.

 In general, contactless smart cards, or cards with mixed operation, are produced by gluing, for example by hot lamination, of superimposed plastic sheets in which the conductive antenna wire has been inserted or inserted. A cavity is then opened in the assembled sheets to create there a housing reserved for an electronic module which is placed so that two of these contact pads are electrically connected to two connection terminals of the antenna conductor.

 Figures 2A and 2B show two sectional views of a chip card 100 with mixed operation produced according to two variants of the invention. The smart card comprises a card body 100 produced, in a conventional manner, by hot lamination of several superposed sheets of plastic material and containing an antenna 120. This antenna 120 is produced on one of the plastic sheets of the assembly, by laminating a conducting wire, or by inlaying, or even by a conventional conductive ink printing technique, such as offset printing or pad printing or even screen printing for example. The antenna generally makes several turns following the outer periphery of the card, to cut off an electromagnetic flux as large as possible. The ends of the antenna 120 are connected to two connection terminals 125 slightly spaced from one another. The spacing between these two connection terminals 125 is chosen as a function of the contact pads 170 of the electronic module that lton will insert into the card.

 In FIG. 2A, the antenna 120 is made in a spiral and its connection terminals 125 are respectively placed outside and inside the spiral. In FIG. 2B, the antenna 120 comprises at least two turns which are produced outside its connection terminals 125. In this case, insulating bridges are produced to enable the ends of the antenna to be connected to the connection terminals 125. The latter case is preferred over the case shown in FIG. 1A because, during the machining of a cavity in the card body, the antenna turns are not updated (but only the terminals of connection) so that they cannot be damaged. In addition, in this case, the postponement of the electronic module M does not require taking any special precautions; unlike the first case (illustrated in FIG. 2A) where it is necessary to protect the antenna turns exposed in the cavity by an insulator, in order to avoid the appearance of short circuits during the interconnection of the module with the antenna connection terminals.

 An open cavity 110 is provided on an upper face of the card body 100. This cavity can be produced in two different ways. A first method consists in machining an opening, corresponding to this cavity 110, in the card body 100, in which the antenna 120 and its connection terminals 125 are embedded. This machining is carried out so that the connection terminals of The antenna are updated. A second method consists in producing the cavity 110 during the assembly of the sheets for constituting the card body by lamination. These sheets then have perforations which, once the assembly has been completed, form the cavity.

 The cavity 110 has for example a shape of a double bowl with two flat bottoms P1 and P2. The first flat bottom P1 is produced in such a way that it is substantially flush with the plane of the connection terminals 125 of the antenna 120. In this way, the first flat bottom P1 makes it possible to update the connection terminals 125. The second Flat bottom P2 is, in turn, produced between the connection terminals 125 and below their plane. This second flat bottom P2 is intended to receive the part of the electronic module M comprising an integrated circuit chip coated in a protective resin.

 This cavity 110, making the connection terminals 125 of the antenna accessible, is also shown in plan view in FIG. 3.

When it is obtained by machining, it is preferably formed by two successive milling operations. Its shape is adapted to that of the electronic module M to be inserted. This electronic module M contains an integrated circuit chip ensuring the operation of the card.

 The electronic module M can be a single-sided printed circuit module (for the production of a card with contactless operation only), or a double-sided printed circuit module (for the production of a card with mixed operation). The module which is described in this description of the invention is a double-sided module. The only difference compared to a single-sided module is that it has, on its upper face intended to be flush with the surface of the card 100, contact pads capable of serving as access contacts for the smart card. . Because of this only difference, the single-sided module is not described, but of course it can also be inserted into the cavity 110 of the card 100.

 The module M, as illustrated in FIGS. 2A and 2B, consists of a double-sided printed circuit carrying an integrated circuit chip. It comprises an insulating sheet 140, on the upper face of which are made first contact pads 160. These contact pads 160 are made by any conventional method, such as printing of conductive ink, or even a deposit of metallization followed by etching for example. The upper face of the module M is defined as being the face intended to be flush with the surface of the card 100. The contact pads 160 are produced according to the usual ISO standards and will serve as access contacts for the smart card.

 On the other hand, second contact pads 170 are produced, in the same way as the first contact pads, on the underside of the insulating sheet 140, that is to say on the face intended to be turned towards inside the cavity 110. These second contact pads 170 are intended to provide the electrical connection between an integrated circuit chip 180 and the antenna 120.

 The integrated circuit chip 180 is bonded to the underside of the insulating sheet 140 and it is connected, by means of soldered wires for example, to the second contact pads 170. This chip 180 and the connecting wires are encapsulated in a protective resin 181.

 The first contact pads 160 of the upper face of the module M can be electrically connected either to the second contact pads 170 via conductive vias formed in the insulating sheet 140; or more simply to the integrated circuit chip 180 by means of other connecting wires which pass through orifices previously formed in the insulating sheet.

 This module M further comprises, on its underside, a sheet of electrically conductive adhesive 130. This sheet 130 makes it possible simultaneously to provide an electrical connection between the second contact pads 170 of the module M and the connection terminals 125 of the antenna 120 as well as a fixing of the module M by gluing.

 The structure of this double-sided module will be better understood with regard to Figures 4 to 6 which illustrate the different stages of its manufacturing process. Double-sided electronic modules, intended to be inserted in mixed-function smart cards, can be manufactured continuously using the same production lines usually used to produce single or double-sided electronic modules.

 Several double-sided modules M1, M2, M3, etc. Mn can therefore, for example, be produced continuously on an insulating film 141. This insulating film is in this case provided with lateral perforations 142 intended to allow it to be driven by machines. Figures 4 and 5 show a bottom view of this insulating film 141, that is to say a view of the underside of the modules M1, M2, M3 ... Mn during manufacture.

 On this lower face are produced the second contact pads 170 of each module, intended to be electrically connected to the connection terminals of an antenna to provide an electrical connection between an integrated circuit chip and said antenna.

 On the other face, not shown but as illustrated in FIGS. 2A and 2B previously described, the first contact pads forming the access contacts of a card are also produced.

 Integrated circuit chips are bonded to the underside of the insulating film 141. They are electrically connected to the second contact pads 170 which are associated with them via conductive wires according to the well-known technique known as "wire bonding" in literature Anglo-Saxon. These chips and the electrical connections are then encapsulated in drops of protective resin 181.

 The next step in the process for manufacturing double-sided modules consists in applying an electrically conductive adhesive film 131 to the insulating film 141 (FIG. 5). This adhesive film 131 has a width less than that of the insulating film 141 so that it does not cover the perforations 142 intended to allow the entrainment of the insulating film.

This electrically conductive adhesive film comprises, for each module M1 ... Mn, a central hole 136 for accommodating the integrated circuit chip encapsulated in the resin 181. It also comprises two notches 135 located respectively between the locations reserved for second contact pads 170. These two notches 135 are for example diametrically opposite and located on either side of the hole 136.

 A final step then consists in cutting the assemblies thus formed to obtain double-sided electronic modules M1, M2, M3 ... Mn. FIG. 6 represents a bottom view of such a module M obtained by cutting the insulating films 141 and conductors 131. This module M is cut flush with the notches 135 (or, in any case, so that the cut passes over the notches 135), so as to separate the adhesive 131 into two zones 133,134, located respectively on one of the second contact pads 170, and in order to ensure electrical insulation of these two zones. Thus, during the transfer of this module M into the cavity 110 of the card body 100, the adhesive 131 makes it possible not only to fix the module, but also to ensure the electrical connection between the contact pads 170 of the module and the terminals antenna connection. The two notches 135 in this case make it possible to avoid a short circuit of the antenna because they provide electrical isolation of the second contact pads 170 covered by the sheet of electrically conductive adhesive 131.

 The electrical interconnection thus produced between the contact pads of the module and the antenna, by means of the electrically conductive adhesive, has very high reliability. It is carried out neatly and with great precision. As a result, the electrical connection between the chip and the antenna is of good quality, which contributes to significantly reducing the number of cards intended for scrap. The cost price of sten cards is therefore also reduced.

 In the examples which have just been described with reference to FIGS. 2A to 6, the cavity 110, formed in the card body 100, as well as the double-sided electronic module M, are produced in a circular shape. But of course, the invention is not limited to this form. In fact, the module M, like the cavity 110, can very well be produced in any other possible shape, such as a rectangular or square shape for example.

 The invention makes it possible to considerably reduce the manufacturing costs of contactless cards. It also uses the same production lines to produce double-sided electronic modules, and mixed smart cards.

Claims (10)

 1. A method of manufacturing a smart card (100), said smart card (100) comprising a card body obtained by assembling superimposed plastic sheets by enclosing, in the superposition, an antenna (120) at the ends which are provided with connection terminals (125) to an electronic module (M), characterized in that it comprises the following steps:  -provision of a card body (100) comprising an open cavity (110), said cavity (110) comprising at least one flat bottom (P1), and said connection terminals (125) of the antenna (120) being updates in the cavity substantially at the level of said flat bottom,  -report of the electronic module (M) in the cavity (110), said module comprising on its underside, turned towards the inside of the cavity, contact pads (170) covered by a sheet of electrically conductive adhesive (130 ) capable of simultaneously ensuring an electrical connection, between the contact pads (170) of the electronic module (M) and the connection terminals (125) of the antenna (120), and a fixing of said module (M).  2. Method according to claim 1, characterized in that the cavity (110) is obtained by machining an opening in the card body, in which the antenna (120) and its connection terminals (125) are embedded.  3. Method according to claim 1, characterized in that the cavity (110) is obtained by lamination of sheets having perforations corresponding to the cavity.  4. Method according to one of claims 1 to 3, characterized in that the antenna (120) comprises at least two turns which are produced outside of its connection terminals (125).  5. Method according to one of claims 1 to 4, characterized in that the sheet of electrically conductive adhesive (130), covering the contact pads (170) reserved for the electrical connection with the connection terminals (125) of The antenna (120), comprises on the one hand a central hole (136) intended to accommodate therein an integrated circuit chip; and on the other hand two notches (135) located respectively between the locations reserved for the contact pads (170), in order to separate said sheet of adhesive (130) into two zones (133,134) electrically isolated from each other .  6. Method according to claim 5, characterized in that the two notches (135) of the sheet of electrically conductive adhesive (130) are diametrically opposite.  7. Chip card manufactured according to one of claims 1 to 6, characterized in that it constitutes a card operating with and without contact and in that it comprises an electronic module (M) double face.  8. Chip card manufactured according to one of claims 1 to 6, characterized in that it constitutes a card with contactless operation and in that it comprises a single-sided electronic module.  9. A method of manufacturing a double-sided electronic module (M) intended to be inserted into a smart card according to one of claims 1 to 7, said method consisting in producing on an upper face an insulating film (141 ) first contact pads (160) intended to serve as access contact for the smart card and, on a lower face of said insulating film (141), second contact pads (170) intended to be connected to the connection terminals (125) of the antenna; then bonding an integrated circuit chip (180) to said underside of said insulating film and making electrical connections between the chip and the first (160) and second (170) contact pads, respectively; said chip and said electrical connections being encapsulated in a protective resin (181), characterized in that it further comprises the following steps:  applying an electrically conductive adhesive film (131) to the underside of the insulating film (141), so that it covers the second contact pads (170), said adhesive film (131) comprising on the one hand a central hole (136) for accommodating the encapsulated integrated circuit chip therein; and on the other hand two notches (135) located respectively between the locations reserved for the second contact pads (170), then  -cut the assembly thus formed at least flush with the notches (135), so that the latter make it possible to separate the film of adhesive (131) into two zones (133; 134) electrically isolated from one of the 'other and located respectively on one of the second contact pads (170).  10. Method according to claim 9, characterized in that the electrically conductive adhesive film (131) is applied to the insulating film (141) by hot lamination.