FR2781589A1 - Device for cutting a cavity close to an antenna contained in an integrated circuit card body - Google Patents

Abstract

The device is designed to cut a cavity (7), in the body of an integrated circuit card (5), close to the antenna. The device includes a conducting reamer (11) rotated by a motor and associated with a vertical displacement system (12) connected to a control circuit. The control circuit includes a servo loop (13) having a first end (14) connected to the reamer and a second end (15) connected to the antenna so that when the reamer enters into contact with the antenna, The antenna electrically connects the two ends of the servo loop and closes them and the control circuit stops the descent of the reamer.

Description

i The present invention relates to a milling device of at least one

cavity directly above an antenna

  drowned in a card body. The invention also relates to

  an antenna for an integrated circuit card and a card body comprising such an antenna. Card bodies of this type are for example used in cards with mixed connection which can be connected to a reader either by a contact connection via the card's external connection pads, or by a connection without

  contact by magnetic or radio coupling.

  A mixed connection card usually includes

  a card body in which a compressed antenna is embedded

  nant a conductive track forming turns and having ends forming connection pads, and a module to

  integrated circuit arranged in a housing of the card body.

  The integrated circuit module is connected to the connection pads of the antenna by means of conductive elements arranged in cavities extending between the connection pads and the housing receiving the module. There are two types of cavities. In a first type, the bottom of the cavity coincides with the connection pad while in the second type the cavity is conical or hemispherical

and crosses the connection range.

  Each cavity is in practice produced by milling using a device comprising a cutter

  rotated and associated with a moving member

  vertical connection to a control circuit. In order to ensure good electrical contact between the connection pads and the conductive elements, it is necessary

  that after the milling of the cavity, the material conduc-

  tor constituting the connection range opposite the

  cavity is exposed on the largest possible surface.

  Therefore, and due to the small thickness of the connection pads (of the order of thirty to forty microns), the descent of the cutter must be stopped very precisely. In particular in the case of milling by means of a cylindrical milling cutter, it is desirable that the connection area is started over only part of its thickness. In existing devices, the control circuit causes the descent of the cutter to stop when the cutter has traveled a predetermined distance which is a function of a theoretical average position of the antenna

  in the thickness of the card body. However, the toler-

  position of the antenna in the card body during manufacture means that there is a risk that when milling certain card bodies the

  strawberry does not reach the antenna or descends too deep-

  relative to it. Expensive controls must therefore be put in place to eliminate unusable card bodies. An object of the invention is to provide a simple, economical and precise means for controlling the descent of

the strawberry.

  In order to achieve this goal, there is provided, according to a first embodiment of the invention, a milling device in which the control circuit comprises a control loop having a first end connected to the cutter and a second end connected to the antenna so that when the cutter comes into contact with the antenna, the antenna electrically connects the two ends of the control loop and closes it. The lowering of the cutter is thus stopped once the servo loop closed, that is to say once the cutter has reached the antenna. The end position of the cutter is then determined specifically as a function of the position of the antenna of the card body during machining. The cavity depth tolerances are therefore relatively small, of the order of a few microns so that the cavities are

  particularly precisely.

  Advantageously, the second end comprises a connector connected to a conductive tab extending laterally projecting from the antenna and opening onto an edge of the card body. The control loop is thus easily connectable to the antenna of the card body

before machining.

  The invention also relates to an antenna

  for integrated circuit cards and one card body

  such an antenna, suitable for milling using

  of a device according to the first embodiment.

  According to a second embodiment of the device

  tif milling, the device comprises two conductive cutters rotated by a motor and associated with a vertical displacement member connected to a control circuit, the two cutters being electrically isolated from each other and the control circuit comprising a control loop having ends each connected to a cutter so that, when the cutters come into contact with the antenna, the antenna connects

  electrically the two cutters and closes the loop of asser-

  screwing. This device then makes it possible to produce two cavities simultaneously, the descent of the strawberries being stopped once the strawberries are in contact with the antenna. In addition, the servo loop of this device does not need to be directly connected to the antenna so that this device is suitable for milling cavities in card bodies of the conventional type comprising an antenna which does not lead to outside of

card body.

  Other characteristics and advantages of the invention will emerge on reading the description which

  follows from a particular nonlimiting mode of implementation

of the invention.

  Reference will be made to the accompanying drawings, among which: FIG. 1 is a top view of an antenna according to the invention,

  - Figure 2 is a top view, with bark

  che, of a card body according to the invention,

  - Figure 3 is a schematic perspective view

  tive of a milling device of a cavity according to a first embodiment of the invention, - Figure 4 is a view similar to Figure 3 of a milling device according to a second embodiment.

  Referring to Figure 1, a general antenna-

  ment designated in 1 comprises, in a manner known per se, a conductive track 2 of copper forming turns and having

  two ends each forming a connection pad 3.

  According to the invention, the conductive track 2 comprises

  takes three tabs 4, adjacent and narrow, extending

  laterally projecting from an external turn of the conductive track 2 towards the outside of the turn. The three tabs 4 extend from one side of the antenna opposite to the

connection areas 3.

  Referring to Figure 2, the antenna 1 is embedded in a manner known per se, for example by rolling, in a card body 5 of insulating material. The connection pads 3 are adjacent to two consecutive edges 8, 9

  of the card body serving as references for positioning

  ment of the antenna in the card body and more generally-

  ment for positioning the card body during

  card manufacturing operations.

  The tabs 4 open onto an edge 6 of the card body 5. It will be understood that during rolling the material of the card body flows between the tabs 4 and is welded on itself. By providing several separate tabs, therefore, a large electrical connection surface is obtained while limiting the risk of delamination of the card body 5 at the tabs 4. In addition, narrow tabs, for example of the same width as the turns of antenna avoid interference

  the functioning of the card during its use.

  After machining, the card body 5 has two cavities 7 each extending directly above a range of

antenna 3 connection 1.

  With reference also to FIG. 3, each cavity 7 is produced using a milling machine comprising a milling head 10 provided with a cutter 11, made of a conductive material, driven in rotation by a motor and associated with a member vertical displacement 12 connected to

a control circuit.

  According to the first embodiment of the milling device, the control circuit comprises a control loop generally designated at 13. the control loop 13 comprises a first end provided with a connector 14 connected to the cutter 11 and a second end provided with a connector 15 intended for

  be connected to the antenna of the card body to be milled.

  During machining, the card body 5 is positioned under the cutter 11 bringing the edges 8 and 9 serving as positioning references against stops 16. The connector 15 is connected to the tongues 4 of the conductive track 2. It will be noted that the tabs 4 preferably open onto an edge of the card body 5 does not

  not serving as a positioning reference so as not to hinder the positioning of the card body.

  After positioning the milling head above one of the connection pads 3, the lowering of the rotating milling cutter is started. When the cutter reaches the connection area 3, an electrical contact is established between the cutter 11 and the connection area 3 of the antenna 1 so that the connectors 14 and 15 are connected by the antenna 1, which leads to the closure of the servo loop. The control circuit then causes the lowering of the cutter 11 to stop, this stop is immediate if the cutter must not cross the connection range, or after a determined time or stroke if the cutter must cross the

connection range.

  FIG. 4 illustrates a second embodiment

  tion of the device according to the invention.

  Elements identical or analogous to those described above will bear an identical reference number. Referring to Figure 4, the

  milling includes two cutters 11 made of a conductive material

  tor. The strawberries are electrically isolated from one of

The other.

  The control circuit connected to the vertical displacement member 12 associated with the cutters 11 comprises a control loop 13. The control loop 13 has two ends provided with connectors 14 connected

with strawberries 11.

  During machining, a simulated milling is carried out.

  tane of the two cavities 7 of a card body 5. During their descent, the cutters 11 simultaneously come into contact with connection pads 3 of the antenna 1. The antenna 1 closes the control loop. The control circuit then causes the descent of the cutters 11 to stop in a manner analogous to the control circuit of the first embodiment. It will be noted that this milling device can be used with traditional cards, that is to say not comprising tabs opening onto the edge of the card. It also allows the integrity of the antenna to be checked when the antenna connects the two cutters and closes the control loop. A card with a faulty antenna will therefore be pierced right through and

  can therefore be easily identified for elimination.

  Of course, the invention is not limited to the embodiment described and it is possible to add to it

  variant embodiments without departing from the scope of the invention

  tion as defined by the claims.

  In particular, the position and the number of the tongues of the conductive track of the antenna are

subject to change.

  In addition, the milling device according to the invention includes any device for producing a cavity using a tool and in particular the devices for

piercing.

Claims (7)

  1. Milling device for at least one cavity (7) in a card body (5) perpendicular to an antenna (1) embedded in the card body, the device comprising a driven conductive cutter (11) in rotation by a motor and associated with a vertical displacement member (12) connected to a control circuit, characterized in that the control circuit comprises a control loop (13) having a first end (14) connected to the cutter and a second end (15) connected to the antenna so that when the cutter (11) comes into contact with the antenna (1), the antenna electrically connects the two   ends of the servo loop and closes it.   2. Milling device according to claim 1, characterized in that the second end comprises a connector (15) connected to a conductive tab (4) extending laterally projecting from the antenna (1) and   opening onto an edge (6) of the card body (5).   3. Antenna for integrated circuit card, including   nant a conductive track (2) forming at least one turn and having ends forming connection pads (3), characterized in that the conductive track (2)   comprising at least one tongue (4) extending laterally   protruding from the conductive track outwards of the turn.   4. Antenna according to claim 3, characterized in that it comprises several adjacent narrow tongues (4). 5. Card body in which is embedded an antenna (1) comprising a conductive track (2) forming at least one turn and having ends forming areas   connection (3), characterized in that at least one conductive tab (4) extends from the conductive track (2) to lead to an edge (6) of the card body.   6. Card body according to claim 5, characterized in that, the connection pads (3) being adjacent to an edge (8) of the card body (5), the edge (6) on which opens the tongue (4 ) is opposite the connection pads (3). 7. Milling device for two cavities (7) in a card body (5) perpendicular to an antenna (1) embedded in the card body, the device comprising two conductive cutters (11) driven in rotation by a motor and associated with a vertical displacement member (12) connected to a control circuit, characterized in that the two cutters (11) are electrically isolated from each other and in that the control circuit comprises a control loop (13) having ends (14) each connected to a cutter (11) so that, when the cutters come into contact with the antenna, the antenna electrically connects the two cutters and closes the loop enslavement.