Registers – Records
Reexamination Certificate
1998-12-03
2001-03-20
Frech, Karl D. (Department: 2876)
Registers
Records
C235S492000, C235S451000, C428S195100
Reexamination Certificate
active
06202931
ABSTRACT:
The invention relates to a memory card having an integrated circuit, and more particularly to a memory card of the type comprising a card body having a face in which (or more precisely through which) an integrated circuit is embedded directly, and having on said face a conductor pattern constituted by a plurality of conductive areas and of associated read/write conductive tracks connecting said areas to the integrated circuit.
BACKGROUND OF THE INVENTION
By way of example, reference can be made to documents FR-A-2 671 461 and FR-A-2 684 471 in the name of the Applicant, which describe a memory card of the above-specified type.
This type of memory card having an integrated circuit embedded in the bulk of the card body is sometimes insufficiently reliable because of the stresses exerted on the edges of the integrated circuit when the card is subjected to bending or flexing. If a high degree of flexing is applied, then the curving of the card body runs the risk of destabilizing retention of the integrated circuit in the card body, and this can go as far as leading to said integrated circuit being expelled. In practice, it is commonplace to cover the conductor pattern, e.g. by means of a varnish that is usually transparent, while leaving the conductive areas of the conductor pattern uncovered. This protective layer participates in holding the integrated circuit in the card body in the event of said card body being flexed, however this holding is of limited effectiveness.
Consequently, there exists a need to improve the retention of an integrated circuit in a card body in order to obtain better resistance to the flexing that may be applied to the card.
This technical problem is already known for laminated cards, i.e. cards of the type comprising a hot-softenable core layer, two covering layers disposed on either side of the core layer, and a module integrated in the core layer and in one of the covering layers by hot-rolling after the various elements making up the card have been stacked on one another. For cards of that type, proposals have thus been made to put into place a belt surrounding the module and extending in the core layer so as to limit the bending forces to which the resin mass constituting the module is subjected, consequently reducing the risk of link members breaking (reference can be made in particular to document WO-A-92/01533 and EP-A-0 466 557).
Nevertheless, it is not possible to use those techniques with an integrated circuit that is embedded directly into the bulk of the card body since it would be quite impossible to place a belt around the integrated circuit.
Proposals have also been made to place a reinforcing plate in the bottom of a housing made in the card body for the purpose of stiffening the zone in which the integrated circuit is installed, as illustrated in document JP-A-61 095 486. Nevertheless, the reinforcement provided thereby is limited since neither the reinforcing plate nor the integrated circuit is embedded directly in the body of the card.
Document EP-A-0 189 039 describes a laminated card in which the integrated card is housed in a recess formed in a hard core disposed in the core layer of the card so as to provide a degree of protection to the integrated circuit when the card is subjected to deformation.
Document EP-A-0 311 434 describes a laminated card having an integrated circuit, in which a reinforcing element in the form of a star is disposed on each of the two faces of the card, on either side of the integrated circuit.
Finally, document EP-A-0 331 316 describes a laminated card in which the integrated circuit is surrounded by a deformable tubular element made of rubber which serves to absorb shocks and deformation when the card is handled.
Furthermore, document EP-A-0 128 822 describes a hot-pressing method of assembling an integrated circuit module in a card body. It should be observed that no reinforcing element is provided in the zone occupied by the integrated circuit.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the invention is to solve the above-specified problem, by designing a memory card of the type having an integrated circuit embedded in the body of the card, in which the structure thereof serves to improve the reliability with which the integrated circuit is held in the card body.
According to the invention, this problem is solved by a memory card of the type comprising a card body having a face in which an integrated circuit is embedded directly, and having on said face a conductor pattern constituted by a plurality of conductive areas and of associated conductive tracks connecting said areas to the integrated circuit, wherein a reinforcing element implemented in the form of a closed ring, is buried in the material of the card body in register with the zone occupied by the integrated circuit, the ring extending in a plane to be substantially parallel to the above-specified face of the card body.
The closed reinforcing ring whose function is to stiffen locally the zone of the card which contains the integrated circuit and its electrical connections, thus achieves local stiffening of the card body, thereby enabling stresses in the zone concerned to be considerably reduced at the surfaces of the integrated circuit, and thus improving the reliability of the electrical connections.
Preferably, the closed ring forming the reinforcing element is disposed in register with the conductive areas of the conductor pattern. The stiffened zone thus extends beyond the zone which is in register with the conductive tracks, thereby providing the electrical connections with very satisfactory levels of reliability.
Preferably, the closed ring forming the reinforcing element is disposed substantially at half-thickness within the card body.
In a particular implementation, the closed ring forming the reinforcing element is a body of revolution about an axis, and the integrated circuit is essentially centered on said axis. The circular ring may also have a section that is rounded or quadrangular in shape: such a section facilitates embedding of the ring in the card body, by encouraging body material to creep around the side walls of said ring.
The closed ring forming the reinforcing element may be made of a rigid material, being made of an injected rigid plastics material, e.g. injectable polyacrylic or homopolymer polyoxymethylene, or a metal, e.g. steel or copper.
The invention also provides a method of fabricating a memory card having at least one of the above-specified characteristics, said method being remarkable in that it comprises the following successive steps:
a) a rigid closed ring is placed on a top face of a first sheet of thermoplastic plastics material;
b) said rigid ring is pressed hot into the first sheet;
c) a second sheet of thermoplastic plastics material is placed on the first sheet fitted with the rigid ring, and the first and second sheets are assembled together by hot pressing so as to constitute an assembly of thickness corresponding to the card body thickness required for the card that is to be made;
d) an integrated circuit is hot-pressed into the free top face of the second sheet until said integrated circuit is completely embedded therein, at a location such that the rigid ring is in register with the zone occupied by the integrated circuit; and
e) a conductor pattern having conducive areas and associated conductive tracks is made in conventional manner on said free top face.
Preferably, step b) of hot-pressing the rigid ring is continued until said ring is partially embedded in the first sheet, and step c) is performed simultaneously with said rigid ring being simultaneously embedded in part in the second sheet. This ensures that the rigid ring is anchored in highly satisfactory manner in the bulk of the card body.
Preferably, the first and second sheets used are of substantially the same thickness, such that the location of the rigid ring lies substantially at mid-thickness within the card body, i.e. it lies in the midplane of said body (i.e. the plane containing its neutral fiber).
Finally, and preferab
Birch & Stewart Kolasch & Birch, LLP
Felten Daniel S.
Frech Karl D.
Schlumberger Systemes
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