Registers – Records – Conductive
Reexamination Certificate
2000-11-29
2003-03-25
Lee, Michael G. (Department: 2876)
Registers
Records
Conductive
C235S492000, C235S488000, C235S489000, C235S442000, C361S737000, C257S679000
Reexamination Certificate
active
06536674
ABSTRACT:
TECHNICAL FIELD
The present invention relates to smart card manufacturing processes, and more specifically a contactless smart card manufacturing process for which the antenna is on a support made of fibrous material such as paper.
PRIOR ART
The contactless smart card is a system being used increasingly in various sectors. In the transport sector, the card has been developed as a means of payment. The same holds true for the electronic wallet. Many companies have also developed identification means for their personnel using contactless smart cards.
The exchange of information between a contactless card and the reader takes place via remote electromagnetic coupling between an antenna embedded in the contactless card and a second antenna in the reader. In order to create, store and process the information, the card is equipped with a chip which is connected to the antenna. The antenna and the chip are generally located on a dielectric support made of plastic. The standard industrial manufacturing process for these components can be broken down into three steps:
the antenna is made on a plastic dielectric support (polyvinyl chloride (PVC), polyesters (PET), polycarbonate (PC) . . . ) using copper or aluminum etching techniques,
the connection of the chip's contact pads to the antenna's contact pads using electrically-conductive ink or epoxy or polymers, commonly referred to as the “flip-chip” die bonding technique.
hot-lamination under pressure of the upper and lower plastic layers of the card body (PVC, PET, PC, acrylonitrile-butadienestyrene (ABS) . . . ), onto the antenna support in order to create a monobloc card.
However, this process generates several major drawbacks. The process leads to a composite stack of glued or heat bonded plastic materials with different thermal expansion coefficients. As a result, systematic unacceptable and irreversible deformation of the cards is observed (twisting, warping), as well as a lack of mechanical resistance when subjected to standardized or equivalent tests.
Furthermore, PVC exhibits poor thermomechanical properties. During the lamination process, material flow is significant and the antenna's shape factor is not maintained. This leads to antenna malfunction as the electrical parameters (inductance and resistance) vary. It is not uncommon to experience antenna breakage in areas subjected to strong sheer stresses. This is particularly the case in angles and at electrical bridging points.
The laminated ISO cards have a total thickness between 780 and 840 &mgr;m. Considering the material flows described above, it is also very difficult to guarantee customers a narrow and controlled distribution of the cards' population.
The plastic heat bonding process used during the lamination operation creates a monobloc card with poor mechanical properties in terms of the restitution of absorbed stresses: during standardized bending and twisting tests, all of the stress applied is transmitted to the chip and primarily to the bonding points which make the connections. The mechanical strength of the bonding joints is subjected to great strain and the slightest imperfection of the chip die bonding operation on the antenna (“flip-chip” die bonding technique) causes the chip—antenna electrical connection to break.
After lamination, the imprint from the copper etching is visible on the printed card bodies. Although this does not prevent the card from operating correctly, the defect is often emphasized by users who are very concerned about the aesthetic criteria.
Furthermore, the cost of manufacturing the card with this process is too high to enable any real increase in its usage.
Lastly, the processes currently used do not produce cards with the possibility to view the poor mechanical treatment inflicted on them by the users, particularly for the purpose of frauding. It is in fact relatively easy for someone with experience in card fraud to destroy the card by folding it repeatedly without it being possible to easily prove any malicious intent afterwards. For example, the antenna may be cut without the card being marked. Commercial policies set up within companies generally ensure the replacement of defective cards free of charge. The systematic replacement of these cards is a source of major supplementary costs for these companies.
SUMMARY OF THE INVENTION
The purpose of the invention is to mitigate these drawbacks by supplying an inventive manufacturing process using a support made of fibrous material on which an antenna is screen printed using electrically conductive ink, thereby significantly reducing the production costs of hybrid or contactless smart cards.
The invention thus relates to a manufacturing method of a contactless smart card with an antenna support made of fibrous material such as paper, which includes the following steps:
A manufacturing process of the antenna consisting in screen printing turns of electrically conductive polymer ink on a support made of fibrous materials and to subject said support to a heat treatment in order to bake said ink,
a bonding step using electrically conductive adhesive to bond the chip's bonding pads onto the antenna's bonding pads, and
A step for laminating the card bodies onto the antenna support consisting in welding on each side of the support at least two sheets of plastic material, forming the card bodies, by a hot press molding technique.
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Delenne Sébastien
Kayanakis Georges
Mathieu Christophe
ASK S.A.
Kim Ahshik
Lee Michael G.
Lydon James C.
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