FR2781588A1 - Non-contact card using electromagnetic wave transmission between the cards integrated circuits and a read/write device and method of card fabrication - Google Patents

Abstract

The card has a card body (10), a semiconductor chip (30) and metal parts (14) forming an aerial. A secondary winding (38) has ends connected to the chip terminals (32,34). The metal parts of the aerial include a coil which forms the antenna connected in series with a primary coupling coil (18). The primary coupling coil surrounds the secondary coil to allow electromagnetic coupling between them. An Independent claim is also given for a fabrication method that involves: (1) providing a chip with a face (36) with two terminals; (2) forming a metal coil whose ends are connected to the terminals on the chip; (3) placing a card of insulating material over the face of the chip; (4) forming an antenna coil and a primary loop on the upper face of the card; (5) connecting the first ends of the antenna and loop together in predetermined zone and then connecting the second ends together; and (6) implanting in the card the chip and the secondary coil in the predetermined zone so that the face of the chip is flush with the first face of the card.

Description

The subject of the present invention is a contactless card and a method

of making such a card.

  Next to electronic memory cards in which the exchange of information and electrical energy between the integrated circuits of the card and the S read / write device is done by ohmic contact via an external electrical contact range so-called contactless cards are now being developed. Such cards are based on a principle of information and energy exchange between the read / write device and the semiconductor chip using an electromagnetic wave transmission. For this, the card is equipped with an antenna connected to the integrated circuits of the card's semiconductor patch. Such cards obviously have the advantage of allowing a dialogue between the read / write device and the card without the user having

  need to insert his card into the read / write device.

  One of the difficulties for producing such cards is that the metallization which constitutes the antenna and which is carried out on or in the card body must be electrically connected to the terminals of the semiconductor chip comprising the integrated circuits. Given the very different nature and very different mechanical properties of the card body, most often made of a thermoplastic material such as PVC or ABS, and of the semiconductor chip, the mechanical strength of this electrical connection may be insufficient when the user of the card subjects it to stresses, for example bending, that are significant in the area of the card body equipped with the

semiconductor chip.

  An object of the present invention is to provide a contactless card in which, in particular, the electrical connection between the antenna and the semiconductor chip is not liable to be mechanically altered during

the use of this card.

  To achieve this object, according to the invention, the contactless card comprising a card body, a semiconductor patch and metallizations forming an antenna is characterized in that it further comprises at least one secondary turn whose ends are connected at the terminals of said chip and in that the antenna metallizations comprise at least one antenna turn connected in series to a primary coupling turn, said primary coupling turn surrounding said secondary turn to achieve magnetic coupling

  between said primary and secondary turns.

  It is understood that the transmission of information and energy between the antenna produced on the card body and the semiconductor patch is obtained by at least one primary turn connected electrically to the antenna and coupled to the

  minus a secondary turn made on the semiconductor wafer itself.

  By such a technique, it is understood of course that the metallizations are entirely carried out either on the semiconductor wafer or on the card body and that the problems of mechanical force applied to the electrical connections between metallizations produced on the card body and

  metallizations carried out on the semiconductor chip itself.

  Another object of the present invention is to provide a method of

  manufacture of a contactless card with the advantages mentioned above.

  According to the invention, the method for manufacturing a contactless card is characterized in that it comprises the following steps: - a semiconductor wafer is provided having a face provided with two contact terminals; - Metallization is formed on said face of the patch forming a secondary coupling turn, the ends of which are electrically connected to the terminals; - It provides a wafer of insulating material having a first and a second main face to form the card body; - Metallizations are made on the first main face of the wafer to obtain an antenna turn and a primary coupling turn surrounding a predetermined area of said first surface, a first end of the antenna turn being electrically connected to a first end of the primary coupling coil, - the second end of the antenna coil is electrically connected to the second end of the primary coupling coil; and - implanting in said wafer said semiconductor wafer equipped with its secondary coupling turn in said predetermined area so that the face of the wafer comprising the turn is substantially flush with said

first side of the plate.

  Other characteristics and advantages of the invention will appear better

  on reading the following description of one or more modes of

  embodiment of the invention given by way of nonlimiting example. The description is

  reference to the appended figures in which FIGS. 1 and 2 are top views showing steps for manufacturing the contactless card; Figure 3 is a vertical sectional view showing the final step of making the contactless card; Figure 4 is an enlarged detail view showing the secondary turn formed on the semiconductor wafer; Figure 5 shows a top view of a semiconductor substrate in which the semiconductor pads shown in Figure 4 are produced; and Figure 6 is a top view showing the placement of the

semiconductor chip.

  Referring first to Figures 1 to 3 we will describe a preferred embodiment of the contactless card. We start from a plate of thermoplastic insulating material 10, the dimensions L and 1 of which are equal to those of the card that we want to make and whose thickness e is slightly less than the final thickness of the card body. In this embodiment, there is made in the plate 10 a recess 12 intended, as will be explained later, to receive the semiconductor wafer. On the upper face 10a of the wafer 10, a first metallization assembly 14 is produced to produce a suitable number of turns for the antenna of the card. These turns are made near the edge of the wafer 10. The turns 14 have a first free end 14a preferably terminated by a contact pad 16. The turns 14 have a second end 14b which is connected to primary turns

  coupling 18 which surround the recess 12 intended to receive the semi-finished pellet

  conductive. These primary coupling turns 18 are in suitable number and the first end of these turns 18 referenced 18a is connected to the end 14b of the turns forming the antenna, the primary coupling turns comprising a

  free end 18b preferably terminated by an electrical contact pad 20.

  The metallization assembly thus produced therefore constitutes on the one hand the antenna turns proper 14 and on the other hand primary coupling turns 18

surrounding the recess 12.

  In a second step shown in FIG. 2, the electrical connection is made between the electrical contact pad 16 of the antenna turns 14 and the electrical contact pad 20 of the turns 18 forming the primary coupling turns. For this, preferably, a layer 22 of an insulating material is deposited locally which covers the portions of turns 14 and 18 extending between the pads 16 and 20. Preferably, the insulating layer 22 covers the terminals 16 and 20, the windows without insulation 24 and 26 being produced opposite the terminals 16 and 20. In a following step, a metallization 28 is produced on the insulating layer 22 which electrically connects the connection terminals 16 and 20. A circuit is thus produced closed comprising the antenna turns 14 and the primary coupling turns 18. In the following step which is more particularly illustrated by FIGS. 3 and 4, a semiconductor patch 30 is prepared comprising two connection terminals 32 and 34 connected to the integrated circuit produced in the patch 30. On the face 36 of the patch 30 comprising these terminals 32 and 34 at least one secondary coupling coil 38 is produced, the ends of which are of course a connection at terminals 32 and 34. The pad 30 is placed in the recess 12 provided in the plate 10 and fixed for example by gluing 40 in the said recess so that the face 36 of the pad is flush with the upper face 10a of the wafer 10. This is shown in FIG. 6. After the wafer 30 has been fixed, sheets of thermoplastic insulating material 42 and 44 are fixed by any suitable means respectively on the upper 10a and lower 10b faces of the wafer 10 This assembly has a total thickness corresponding to that which one

  wants to give the body of the contactless card.

  In addition, to further improve the quality of the electro- coupling

  magnetic between the secondary turns 38 and the primary turns 18, it is possible to deposit in the zone extending between the primary and secondary turns a layer of a ferromagnetic material which can for example constitute the material

  adhesive used to fix the patch 30 in the recess 12.

  As regards the production of the turns 14 and 18, they can be carried out either by screen printing using a conductive ink, or by fixing, for example by laminating thin conductive elements having the form

  required using a printed circuit type technique.

  Preferably also, secondary turns 38 produced on the semiconductor wafers can advantageously be deposited on the semiconductor substrate 46 in which the various operations have been carried out making it possible to obtain the different semiconductor wafers 30. The secondary turns 38 can be carried out during the other operations necessary for the preparation of the semiconductor pads 30. After the turns 38

  the substrate 46 is cut to obtain the individual pellets.

Claims (8)

  1. Contactless card comprising a card body (10), a semiconductor patch (30) and metallizations (14) forming an antenna, characterized in that it further comprises at least one secondary turn (38), the ends are connected to the terminals of said patch and in that the antenna-forming metallizations comprise at least one antenna-forming turn (14) connected in series to a primary coupling turn (18), said primary coupling turn surrounding said secondary turn to produce a coupling   electromagnetic between said primary and secondary turns.   2. Card according to claim 1, characterized in that it comprises: a plurality of turns (14) forming an antenna, a plurality of primary turns (18) for coupling, the end of a turn forming an antenna being electrically connected to the end of one of the primary coupling turns; and   at least one secondary coupling turn (38).   3. Card according to claim 2, characterized in that the antenna turns (14) are arranged near the edge of the body (10) of the card, and in that the primary coupling turns (18) surround the secondary turn of coupling (38).   4. Card according to any one of claims 2 and 3, characterized   in that the secondary coupling turn (38) is carried out directly on the   face (36) of the semiconductor wafer comprising the terminals (32, 34).   5. Method for manufacturing a contactless card characterized in that it comprises the following steps: - a semiconductor wafer (30) is provided having a face (36) provided with two contact terminals (32, 34) ; a metallization (38) is formed on said face of the patch forming a secondary coupling turn, the ends of which are electrically connected to the terminals; - A wafer (10) of insulating material having a first and a second main face is provided to form the card body; - Metallizations are made on the first main face to obtain an antenna turn (14) and a primary coupling turn (18) surrounding a predetermined area of said first surface, a first end of the antenna turn being electrically connected to a first end of the primary coupling coil, - the second end of the antenna coil is electrically connected to the second end of the primary coupling coil; and - implanting in said wafer (10) said semiconductor patch (30) equipped with its secondary coupling coil, in said predetermined area so that the face (36) of the patch comprising the coil   is substantially flush with said first face of the wafer.   6. Method according to claim 5, characterized in that a plurality of turns forming an antenna (14) close to the edge of the wafer are produced, a plurality of primary coupling turns (18) surrounding said predetermined area are produced, and that, to connect the second end (24) of the turns forming the antenna to the second end (26) of the primary coupling turns, said turns are locally coated with an insulating layer (22), and a connection metallization is made ( 28) between said two second ends, said connecting metallization being arranged partly above said layer insulating.   7. Method according to any one of claims 5 and 6, characterized   in that said turns are produced by screen printing with a conductive ink.   8. Application of the method according to any one of claims 5   7 to the production of a plurality of contactless cards, characterized in that a plurality of semiconductor wafers (30) are provided in the same semiconductor substrate (46) each provided with two contact terminals ( 32, 34); at least one secondary turn (38) of coupling is produced on each portion of the substrate corresponding to a pellet; said pellets are separated from each other; and implanted in each insulating plate (10) provided with its   metallizations (14, 18) one of said pellets.