Registers – Records – Conductive
Reexamination Certificate
2000-03-24
2002-09-10
Lee, Michael G. (Department: 2876)
Registers
Records
Conductive
C235S489000
Reexamination Certificate
active
06446874
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the fabrication of electronic modules to be integrated into an electronic card, such as a smart card or an electronic label.
BACKGROUND OF THE INVENTION
The electronic module in a smart card or the like includes at least one microcircuit and an interface which can be a contact terminal assembly in the case of conventional contact-type smart cards or one or more antennas providing contactless communication in the case of contactless smart cards and electronic labels. In the case of hybrid smart cards, the interface includes a contact terminal assembly and an antenna.
One standard process for fabricating smart cards produces electronic modules in series on a continuous support film which is then cut up to fix the modules into a cavity formed in the body of the card. To be more precise, microcircuits or chips are glued to the support film carrying an interface and the connections from the microcircuit to the interface are then made. The connections and the chip are then covered with a coating, in particular a drop of thermosetting resin providing mechanical protection.
This is followed by an operation of fixing the electronic module into the cavity in the card, usually referred to as “carding”. An adhesive such as a cyanoacrylate glue or even a heat-activated adhesive can be placed in the cavity for this purpose. Alternatively, a heat-activated adhesive can be hot-laminated onto the film after the coating operation and before cutting out the module. The adhesive is then re-activated by hot pressing once the module has been placed in the cavity.
The protective resin for small chips is usually deposited directly onto the support film. In contrast, for large microcircuits, and in particular rectangular ones, in order to obtain a reproducible shape it is necessary to delimit the surface of the drop of resin by means of a “barrier” deposited around the electronic module. The use of a barrier facilitates depositing the resin and in some cases removes the need for the milling operation that is otherwise necessary to obtain the final thickness of the module.
The barrier can be a polymer (epoxy, silicone, polyester) barrier deposited by means of a syringe (“dispensed”) or by screenprinting. The barrier can instead be a pressed metal frame glued to the support film.
The technique using a barrier has a number of drawbacks. Firstly, its cost is relatively high and adds to the unit cost of the electronic card. In the case of a silicone barrier, there are secondary effects (pollution of the surfaces to be glued). The operation of depositing the resin must be carefully controlled to prevent the resin overflowing, which constitutes a cause of rejection. Finally, it is difficult to dispense with the milling operation in the case of thermosetting resins.
To avoid the above drawbacks, another process includes steps of cold laminating a perforated adhesive tape onto the support film, casting a resin in the openings formed by the perforations in the adhesive tape by a process referred to as “shuttering”, setting the thickness by stamping, if necessary, and peeling off the adhesive tape.
SUMMARY OF THE INVENTION
This process uses a particular consumable, namely the adhesive tape, which is of non-negligible cost. Also, to reduce the cost of this technology, the adhesive tape must be cut and applied and the resin must be deposited and the tape removed on the same machine. What is more, not even the slightest residue of adhesive on the film can be tolerated as this may compromise the “carding” operation. These two objectives are difficult to achieve with high efficiency, the slightest offset in the registration of the adhesive tape leading to a high reject rate. It is difficult to apply a cold adhesive which must be peeled off after coating without the adhesive beginning to peel in the vicinity of the cutout, which causes the resin to leak beyond the intended area.
Another technique is described in European Patent Application EP-A-0 201 952. It includes the steps of cold laminating a perforated adhesive tape onto a film that is bare and/or incorporates the chip and/or the connecting wires, said tape consisting of a mass of adhesive and a removable protective film, spraying a varnish onto the protective film coating the chip and the connections in this way, removing the protective film, which has served as a mask, cutting out the module using a punch/die-type tool and placing the module directly in the cavity.
This process is difficult to use and its mechanical reliability is debatable. During cutting, the remaining mass of adhesive may stick to the die and/or the card. A second protective film with openings corresponding to the modules is then placed over the mass of adhesive.
This process has the drawbacks of involving too many process steps and of requiring a specific consumable, in the form of the second film, and is therefore costly to implement.
The problem addressed by the invention is that of providing a simple, reliable and economic method of fabricating electronic modules for electronic cards.
The proposed solution aims not only to reduce the number of process steps but also to eliminate the use of consumables. To this end, the principle of the invention is to use the adhesive employed for fixing as a barrier to or delimiter of the coating resin.
To this end, the invention provides a method of fabricating at least one electronic module or label which is adapted to be rendered adhesive, said module or label including a support film, at least one microcircuit and at least one interface of the contact and/or antenna type connected together by connections and disposed on the support film, a coating resin protecting at least said microcircuit and said connections, said coating resin being disposed over a predetermined area, and an external activatable adhesive, said method including the following steps:
a) an insulative film is supplied including at least one contact and/or antenna type interface,
b) an adhesive tape is supplied including an activatable adhesive and a removable protective film, said tape including at least one perforation corresponding to the area of the resin on the module or label,
c) the adhesive tape is applied to the support film so that said perforation coincides with the area of the resin and said adhesive is activated so that it fixes the tape to the film, and
d) the coating resin is dispensed over the intended area at least within the perforation and in contact with the perforation, the microcircuit having been fixed to the support film connected to the interface after one of the preceding steps.
In the case of series fabrication of media provided with an electronic module, such as smart cards, or with a label, the preceding steps are performed, the support film and the tape are provided in roll form, the former including a plurality of interfaces, the latter including a plurality of perforations. The protective layer is then removed from the adhesive tape and the modules or labels are cut out before gluing them to a support of the body of the card by activating the adhesive tape.
The method according to the invention is particularly advantageous for fabricating smart cards since no dedicated consumable material is used for shuttering the resin, because the fixing adhesive is used for this purpose, and the number of process steps is reduced, because the separate operation of depositing the barrier is eliminated. Also, equipment and processes known in the art are used, which facilitates industrial application.
Minimising the number of process steps increases efficiency and reduces fabrication cost.
In the case of small microcircuits, for which a barrier is not normally used, the invention increases the volume of resin around the connecting wires and thus provides a form of packaging which is more rigid and therefore more resistant to mechanical stresses (repeated bending and twisting). This increase in reliability is achieved with no increase in unit cost.
The adhesive tape can be applied to the support film at various
Elbaz Didier
Fidalgo Jean Christophe
Burns Doane Swecker & Mathis L.L.P.
Cyr Daniel St.
Gemplus S.A., Inc.
Lee Michael G.
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