WO2005059818A1

WO2005059818A1 - Burning in dual interface cards by internal continuos grid contacts

Info

Publication number: WO2005059818A1
Application number: PCT/FR2004/003187
Authority: WO
Inventors: Jacques Venambre; Guy Enouf; Jérôme Bouvard
Original assignee: Oberthur Card Systems Sa
Priority date: 2003-12-11
Filing date: 2004-12-10
Publication date: 2005-06-30
Also published as: FR2863747B1; FR2863747A1

Abstract

The invention relates to a microcircuit card whose body is provided in the thickness thereof with terminals (3, 4) for connecting to a first component and a second component (20) comprising a microcircuit (22) and internal contacts (23, 24) connected to said connection terminals by a mechanical and electric connecting material. The inventive card is characterised in that at least one of connection areas formed by connection terminals and the internal contacts has a geometry comprising conductive strip threads (3A, 4B) which are separated by spaces whose width is at least equal or greater than said strip threads.

Description

RELIABILITY OF DUAL INTERFACE CARDS BY INTERNAL CONTACTS WITH A CONTINUOUS GRID

Field of the Invention The invention relates to a microcircuit card comprising a card body carrying a microcircuit and in the thickness of which are provided terminals for connection to a component which it is desired to connect to internal contacts of this microcircuit . It is aimed in particular, but not exclusively, at cards of the dual interface type, that is to say cards which operate at the same time thanks to data transmitted by external contacts flush with the surface of the card (according to the standard ISO 7816) and thanks to data transmitted without contact, via an antenna. Such a card is often called “Dual Interface” or “Combi” .0 Cards of this type are known from document FR-2716281; these cards include a card body and the same microcircuit for these two types of transmission. The microcircuit is part of a module (sometimes also called a sticker) comprising a support film carrying this microcircuit on an internal face. This support film also comprises, on its external face, 5 external contacts connected to the microcircuit and, on its internal face, internal contacts also connected to the microcircuit and cooperating with antenna connection terminals or terminals, located in the thickness of the card. This module is fixed in a cavity of the card body in the thickness of which the antenna is made, and the antenna terminals, made in the thickness of this card, are accessible in this cavity. Technical problem The market for these cards "Dual Interface" matures, but a ^"technical problems of these products remains reliability, particularly regarding the electrical and mechanical connection between the module and the antenna. In general, the manufacture of a “Dual Interface” card consists in preparing a film generally made of polymer (PVC, PET, polycarbonate), called inlay, on which electrically conductive tracks (copper or conductive ink) are created which must form the antenna , then laminate this inlay between layers, generally of polymer, until the card body of the desired thickness is obtained. A cavity is then produced in this card body, before carrying out a so-called inserting operation, according to which is fixed in this cavity the module, prepared in addition so as to have on its microcircuit a radio-frequency part adapted to cooperate with this antenna. t both provide a mechanical link between the module and the card body and an electrical connection between the radio-frequency part and the antenna. This fixing implies good adhesion, good comparison of the surfaces to be electrically connected, without however leading to degradation of the elements to be fixed. There are few connection techniques between module and antenna. We thus know the use of conductive adhesives or conductive pastes, but the use of anisotropic adhesives (in a perpendicular direction between the surfaces to be joined) is currently considered the most promising connection method. Anisotropic adhesives (we also sometimes speak of anisotropic adhesives when this adhesive is present in the form of a film rather than a paste) have two distinct components: • An adhesive mass (polyester, or phenolic or other) reactivable to hot and under pressure, creating the bonding function, • Metallized particles, glass or polymers, embedded in this mass, and used to electrically connect the parts to be bonded. Adhesion and electrical conduction Adhesive masses generally have fairly good adhesion to the materials from which card bodies or support films are commonly made, PVC in most cases, but lower adhesion on electrically conductive tracks, generally in copper, which constitute the antenna connection terminals. On the other hand, the surface density (parallel to the surfaces to be bonded) of the metallized particles present in the adhesive mass (approximately 40 to 150 / mm ² ) is calculated so as not to allow lateral electrical conduction (risk of electrical leaks on the parts to be isolated). However, the electrical conduction in the Z axis (that of thickness) is only done well from a minimum threshold, typically of the order of 30 particles / mm ² . Taking into account the average sizes of these particles but also the distribution of their diameters (25 μm min / 55 μm max), obtaining a good electrical connection requires providing, when designing the product, a copper surface greater than a given threshold. However, since increasing the copper surface is equivalent to reducing the overall adhesion of the adhesive, with therefore a risk of subsequent detachment of the module, and consequently a risk of electrical disconnection between the antenna and the microcircuit and therefore of non-functionality of the product (it should not be forgotten that the main application for the moment of these cards is transport, hence daily use of the cards, hence the requirement for a high level of reliability), we understand that 'There is a compromise to be defined between adhesion and electrical conduction, to which corresponds a given ratio between copper surface and overall bonding surface; a ratio of 10 to 20% may seem an acceptable value in this regard. Superimposition of internal contacts and connection terminals The lamination operation which consists of hot pressing and under pressure of plastic sheets, for example PVC, on either side of the inlay comprising the antennas, poses the problem of positioning of these antennas relative to the future cutting of card bodies and their cavities. The sheets being opaque, the use of optical fibers illuminating by transmission alignment patterns provided in these sheets only partially addresses this problem of offset. The precision requested is indeed currently +/- 0.5mm, but more than 25% of the products may have offsets of up to 0.8mm or more; in this case, when inserting, the superimposition of the internal contacts of the module and the antenna connection terminals is poor and results in a large reduction in the actual electrical contact area

Deformation of plastic sheets due to connection terminals. During the lamination leading to the assembly of the sheets forming the card body, the heat flow in the thickness direction of the sheets to be assembled meets, either only PVC (or other polymer) or the electrically conductive material, copper most often inserted on the inlay to form the tracks or the connection terminals. Copper, not having the same thermal conductivity as the plastic materials of the sheets, acts as a radiator and modifies the temperature gradient (this is also true for other conductive materials). When cooling, constraints are created in the stacking of plastic sheets between the 100% plastic areas and the plastic + Copper areas, hence the appearance of reliefs corresponding to the shape of the antenna and its connection terminals. This poses a double problem: • aesthetic problem, and • difficulties for the correct realization of the subsequent graphic personalization of the card (printing on the non-flat outer surface of the stack). The subject of the invention is a microcircuit card comprising, in the thickness of its card body, terminals (at least one terminal) for connection to a component which have a geometry leading to good reliability of the electrical contact between these terminals of connection and internal contacts of one or of the module carrying this microcircuit, while ensuring a good mechanical connection, by eliminating the problem of positioning the connection terminals in the card body (or even the positioning tolerance of the internal contacts of the module when inserting), and minimizing the deformations likely to appear when laminating the sheets to form the card body. The aforementioned problems with regard to the reliability of the electrical connection arise both for the internal contacts and for the connection terminals (as regards the adhesion of the facing surfaces), so that, quite generally , the invention relates to a microcircuit card comprising, in its thickness, at least one terminal for connection to a first component and / or at least one internal contact of a second component comprising this microcircuit, the geometry of which leads to a good reliability of the electrical contact between these connection terminals and these internal contacts. It should be noted that these problems, described above with regard to “Dual Interface” cards are very generally found when one seeks, in a microcircuit card, to connect internal contacts of a module to component connection terminals which are arranged in the thickness of the body of this card. This is how these problems are likely to arise when trying to connect to an antenna, but also to a display screen, a heat sensor, a battery, a fingerprint sensor, etc. . More generally, the problems cited arise when one wants to connect a first component (antenna, sensor or other) to a second component (module, other sensor or other) comprising a microcircuit. Furthermore, the above problems are sensitive not only with an anisotropic adhesive, but also, although perhaps to a lesser extent, with other types of mechanical and electrical bonding materials. DESCRIPTION OF THE INVENTION The invention proposes for this purpose a microcircuit card comprising a card body in the thickness of which are provided terminals for connection to a first component, and a second component comprising this microcircuit and internal contacts connected to these connection terminals by a mechanical and electrical connection material, characterized in that at least one of the connection zones constituted by the connection terminals and the internal contacts has a geometry comprising strands of conductive track separated by spaces at the less as wide as these strands. It should be noted that the only difference between the first and second components is that one arbitrarily chooses to designate the component comprising the microcircuit as being the second component and that, in particular, both the connection terminals and the internal contacts are in the thickness of the card body. By strand is meant according to the invention a portion of conductive track, that is to say a thin or thick layer in the sense of microelectronic technologies, for example deposited by lithography, the width of which is substantially less than their length, in a ratio of at least 3. Thus defined, the invention may appear to have similarities with the teaching of document WO-98/38598 which relates to the connection of a module to a wire antenna whose ends are folded back into pins hair. It should however be noted that, if this document mentions the possibility of making connection zones by filing and delimitation, it is to reject this technology which is deemed to lead to connection terminals of too large dimensions. This is why he teaches to use a wire which is placed on one side of a layer but which, in the connection area, is forced to pass through this layer from place to place to allow connection with a module; in fact, the wire antenna is formed on a face opposite to the one where the connections are made. It follows that the connection zone facing the internal contacts of the module is formed of small conductive islands; these are simple dots and certainly not strands. Currently the shape of the connection terminals is very often rectangular or circular, and the massive surface of conductive material (most often copper) is several mm ² . According to the invention, these massive shapes are replaced, over an at least equal connection area, by geometries (of combs, loops or grids, in particular) forming an alternation of conductive strands and free zones. Insofar as the problems that the invention aims to solve are mainly related to the geometry of the connection terminals, a particularly advantageous case is that where it is the connection terminals which have a geometry comprising such strands of track separated by spaces at least as wide as these runways. This solves in particular the problem linked to the extra thicknesses due to the massive connection zones, while leaving free, in the area of the connection terminal, zones of better adhesion than the conductive material constituting the track strands. The fact that the connection zones are formed of conductive strands and of free zones (allowing access, for the fixing material, to the material on which the track strands are formed) makes it possible to provide connection zones (i.e. - say areas where a connection will be possible, even if, after mounting, the connection is actually made on a smaller area) very large. It is therefore possible to provide that the connection terminals are contiguous, which does not pose any particular problem from the point of view of insulating the terminals from one another when an adhesive or anisotropic adhesive as a mechanical and electrical bonding material. It can be noted in this regard that such an anisotropic adhesive cannot be used in practice with a wire because, with a wire, the area available for connection in the direction of connection is too small. Preferably the track strands are electrically mounted in parallel. It is clear that such parallel mounting would be impossible with a wire antenna as proposed in the aforementioned document WO-98/38598. But a parallel assembly has the advantage over a series assembly that, in the event of deterioration of a strand, the consequences are much less on the overall performance in the event of parallel assembly than in the case of an assembly in series: in one case, the other strands remain available to participate in the connection, while in the other case, only part of them remains available. One of the consequences is that it is possible to provide for the strands of the track of small thicknesses, typically thinner than those conventionally used for antenna tracks (typically of the order of 35 microns) without too great risk (linked to operations of forming tracks or inserting, that is to say mounting the module in the card body) on the quality of the connection within the final card: this results in less geometric disturbances in the thickness of the final card, and contributes to solving the technical problem targeted by the invention. Thus, advantageously, the conductive strands have a thickness at most equal to 30 microns, preferably at most equal to 15 microns (for example of the order of 12 microns). According to other preferred characteristics of the invention, possibly combined: - these strands cross at least one other conductive strand transversely to these: the fact of connecting these strands has the advantage of increasing the possible points of connection to the internal contacts of the module, while minimizing the consequences of the degradation of one of these strands, - these strands cross this other strand at their ends, which corresponds to maximum occupancy of the mechanical connection surface, - these strands cross a plurality other conductive strands so as to form a conductive grid, which corresponds to an optimum from the point of view of electrical conduction, without having to cover the entire bonding surface with conductive material, - this conductive grid comprises meshes of at least two different sizes, defining areas with different relationships between the strand surface and the total surface, which makes it possible to adapt to the geometry of the internal contacts with which these connection terminals must cooperate, - these strands close on them so as to ^" form loops, which corresponds to a another configuration which is easy to implement, - these loops intersect, which makes it possible to obtain the same advantages as with a mesh of rectilinear strands, - at least some of the strands have a periodic arrangement, which is common to the above-mentioned configurations grids or loops, - these conductive strands are divided into two batches substantially symmetrical to each other, which simplifies the configuration of the connection terminals (the drawing of one gives the other) while balancing the mechanical strength of the two terminals, - the second component is advantageously mounted in a cavity, which makes it possible to accommodate the microcircuit satisfactorily without having to set too severe constraints on it. size, - this cavity is preferably through, which corresponds in particular to the case where the second component is a module, - these connection terminals include strands mounted in parallel and oriented towards the center of the cavity, which allows in particular good conduction with the internal contacts when they are arranged, on the other hand, in a ring configuration, - these connection terminals are arranged facing each other of this cavity, - these connection terminals are arranged on steps bordering the cavity, which allows the attachment of modules comprising a large microcircuit, it being recalled (see above) that they can be contiguous so as to jointly occupy almost the entire surface of the step when it is desired to maximize the available area to make the connection, - the internal contacts of the second component have a geometry comprising conductive track strands (regardless of whether the terminals of c whether or not they are formed); it is clear that most of the advantages mentioned above about advantageous features connection terminals formed of track strands can be found for the internal contacts, in particular when these are preferably mounted in parallel, - of course it is particularly advantageous that both the connection terminals and the internal contacts have conductive track strands: it is recommended that these strands have different directions so that they intersect, - the total surface of the internal contacts is less than the total surface of the connection terminals, - the strands of the connection terminals and those of the internal contacts are opposite in zones whose overall surface is at least 1.8 mm ² , - the ratio between the surface of conductive material and the free surface of underlying material is between 20% and 40% , preferably between about 25% and 35%, - the second component is a module comprising a support film on the internal face of which the microcircuit and the internal contacts are attached while on the external face are provided external contacts; as a variant, this second component can be a fingerprint sensor, a display screen, etc., - the component is an antenna made in the thickness of the card body, - the connection terminals include strands which have a width which is substantially equal to that of the antenna tracks, - the width of the strands of the connection terminals is between 100 microns and 400 microns, - the width of the strands of the internal contacts is between 150 microns and 500 microns.

Description of the invention Objects, characteristics and advantages of the invention appear from the following description, given by way of non-limiting illustration with reference to the appended drawings in which: FIG. 1 is a schematic exploded perspective view of the body of a card according to the invention, in an intermediate stage of manufacturing this card,

FIG. 2 is an exploded sectional view of this body, in this step,

FIG. 3 is a perspective view of this body before fitting a module,

- Figure 4 is a sectional view of this body, before this installation, - Figure 5 is a schematic view showing this body and the module about to be put in place,

FIG. 6 is a detailed sectional view showing the cavity of the card body in which the module has been put in place,

FIG. 7 is a bottom view of this card, showing the connection terminals and the internal contacts, by transparency through the card body,

FIG. 8A is a detail view of another geometry of connection terminals, in the form of a grid,

FIG. 8B is a detailed view of a variant of this geometry, with the same thickness of conductive strands as in FIG. 8A but with a smaller mesh size,

- Figure 8C is a detail view of yet another variant of this geometry, with the same thickness of strands as in Figures 8A and 8B, but with an even smaller mesh size, - Figure 9 is a view detail of another geometry of connection terminals, with different mesh sizes, inside the contour of the cavity of the card body,

FIG. 10 is a view schematically showing the superimposition of internal contacts of a module and connection terminals according to another embodiment, in the form of grids formed on a step bordering the cavity, - Figure 11 is another view showing the superposition of internal contacts of a module with connection terminals, according to another embodiment, with strands generally oriented towards the center of the cavity, - Figure 12 is another view representing the superposition of the internal contacts of a module and the connection terminals according to yet another embodiment, with strands in loops, and - FIG. 13 is another view showing the superposition of the internal contacts of a module and connection terminals according to yet another embodiment, with zig-zag strands. FIGS. 1 to 7 represent stages in the production of a microcircuit card of the “Dual Interface” type according to an embodiment according to the invention. Figures 1 and 2 show a stack of sheets intended, by its assembly, to form the body of this card. Inside this stack is a sheet 1 called an inlay on which a unitary antenna 2 has been deposited, in the form of substantially planar tracks 2A, terminated by two connection terminals 3 and 4. According to the invention, the at least one of the connection zones formed by these connection terminals or by the internal contacts with which these terminals must cooperate have a geometry comprising strands of conductive track separated by spaces at least as wide as these strands. More particularly, in the example considered here, these connection terminals have a geometry comprising conductive strands 3A and 4A advantageously mounted in parallel, being separated by spaces at least as wide as these strands. Indeed, these connection terminals are formed of strands starting from an external contour, here of generally rectangular shape and formed of two C facing each other, marked 3B or 4B. The strands of each terminal here extend to another conductive strand 3C or 4C which they cross at their ends. This other strand of each terminal is here parallel to the other strand of the other terminal. In the example considered, these strands are even arranged, geometrically, parallel to each other, in different directions within the terminal 3 and within the terminal 4, respectively. These strands are advantageously tracks of the same nature as the tracks constituting the turns of the antenna, copper in practice. And their width and their thickness are preferably equal to those of these turns. As a variant, these runway strands are made of aluminum. The antenna 2 is here represented on an individual basis. In reality these antennas are received in the form of large rectangular boards, for example of 591 mm x 370mm comprising 36 antennas (6x6) distributed with an X pitch of 91.2mm and a Y pitch of 57mm. The inlay 1 is conventionally made of PVC 200 μm thick and the turns are formed from a copper layer 35 μm thick and 120 μm wide, photo-etched representing the design of the antenna. Other materials are possible for the inlay, in particular epoxy glass, polyethylene terephthalate (PET or PETS), polycarbonate, polyimide, ABS, etc. while the turns can be made of another conductive material such as aluminum. The tracks constituting here the antenna are interrupted at two points 2B and 2C intended to be electrically connected under the plane of these tracks, by a bridge (not shown) of any suitable known type made on the underside of the inlay. The sheets between which the inlay 1 is arranged in FIG. 1 are in fact multiple, as is clear from FIG. 2. This inlay is first of all interposed between two layers 11 and 11 ′ having a compensating role, themselves bordered by two printing layers 12 and 12 'covered with two covering layers 13 and 13', generally transparent. These layers 11-13 and 11 '-13' are for example made of PVC or equivalent material. The function of the compensation layers is in particular to absorb the reliefs due to the presence of the copper tracks, while the printing layers are intended to receive images or printed characters in a lasting manner. The layers 11 and 11 'have for example a thickness of 100 microns, the layers 12 and 12' a thickness of 140 microns and the layers 13 and 13 'a thickness of the order of 40 to 80 microns. The final thickness is for example of the order of 800 microns. The assembly of these layers is done by a hot lamination treatment, with in principle the application of a pressure shown diagrammatically by the arrows appearing in FIGS. 1 and 2. At the end of this lamination, the antenna is not more visible. As indicated above, this lamination is done in practice on large area sheets. A calendering operation then makes it possible to isolate each unitary card body. Figures 3 and 4 show a step of making a cavity

15 intended to receive a module (see FIGS. 5 to 7). The machining of this cavity is conventionally carried out by milling. In the example shown here, the cavity comprises two zones 15A and 15B superimposed but of different dimensions. It thus appears a step 16 bordering this cavity. As can be clearly seen in FIG. 4, the upper zone 15A is cut out in the layers 11-13 situated above the inlay, while the lower zone 15B, of smaller dimensions, is hollowed out in these layers 11- 13, but also in the inlay and in the lower compensation layer 11 ′. The machining of this cavity results in the removal of a central part of the pattern formed jointly by the connection terminals 3 and 4 of FIG. 1, but there remain, on the step, conductive strands mounted in parallel and s extending to the internal edge of the step. This step is for example located at 270 microns under the upper face of the card body, while the total depth of this cavity is for example 580 microns. FIG. 5 represents, in perspective, the card body of FIGS. 3 and 4, as well as a module 20 ready to be inserted therein. This module notably includes a support film 21 here shown with its internal face turned upwards, so that the microcircuit 22 can be seen there, as well as conductive strands mounted in parallel forming internal contacts 23 and 24 of this module. As can be seen from FIG. 6, this support film 21 carries electrically conductive zones on its two faces, namely external contacts 25 on its external face intended to be accessible from the outside, and tracks on the internal face. connected to the microcircuit 22 by conductive wires 26, for example made of gold, and connected to the internal contacts 23 and 24. These internal contacts are for example made of gold, even palladium or copper. The fact that the cavity has a step separating two zones 15A and 15B facilitates the positioning of the module so that its internal contacts are in contact with the connection terminals of the antenna, while making it possible to accommodate the protruding microcircuit down relative to the support film. The deep zone 15B also makes it possible to house a resin 27 encapsulating this microcircuit. This resin preferably extends to the bottom of this deep portion 15B so as to contribute to the fixing of the module in the cavity. The connection between the internal contacts of the module and the connection terminals is ensured by an adhesive 28 in which are embedded electrically conductive balls. The inserting operation consists of depositing the resin in the bottom of the central cavity (see two drops 27A in FIG. 5) and the adhesive on one of the faces to be bonded (for example on the step), and place the previously prepared and cut module in the cavity and stick it by pressure and heating (reactivation of the anisotropic adhesive). The anisotropic adhesive or glue makes it possible both to electrically connect the antenna connection terminals to the internal contacts of the module and to mechanically fix this module, by its periphery, in the cavity. FIG. 7 shows from below, by transparency through the lower layers of the card body, the strands constituting the connection terminals and internal contacts of the module. It is observed that the strands 3A constituting the connection terminal closest to the outer edge of the card body cross the strands 23A constituting the corresponding internal contact of the module, while the strands 4A cross the strands 24A of the other internal contact of the module . Each crossing of these strands constitutes an electrical connection between these terminals and these contacts. It is easy to understand that, thanks to this configuration of the connection terminals, a deviation of the antenna position from its set position relative to the edges of the card does not prevent the formation of a significant number of elementary contacts between antenna and module. The tolerance constraints concerning the positioning of the antenna in the stack during lamination are therefore much less strict than with the conventional geometries of the connection terminals. These constraints are all the less severe since here, the internal contacts of the module also consist of strands electrically mounted in parallel. On the other hand, a local detachment of the module vis-à-vis the tier does not necessarily render the card inoperative since other contact sites remain. On the other hand, the step area occupied jointly by the conductive strands forming one of the connection terminals (here the entire area of the step) is significant, while leaving a significant fraction of the area available for good adhesion with the areas in question. look at the module. The mechanical strength of the connection between the cavity zone carrying the conductive strands and the zone of the module carrying the internal contacts is therefore improved compared to the case of conventional solid connection terminals. It should be noted that this advantage is already obtained when the connection terminals have a geometry comprising strands mounted in parallel, independently of the geometry of the internal contacts of the module, insofar as the mechanical strength of the "material" zones plastic + conductive material "between such strands is already better than between zones" conductive material + conductive material ". But the overall mechanical strength is of course even better when there are both in the connection terminals and in the internal contacts of the zones of plastic material opposite other zones of plastic material. Furthermore, the strands constituting these connection terminals being generally narrow, they generate, during lamination, much less deformation of the compensation layers than connection terminals massive classics. As has just been detailed, the aforementioned advantages are already obtained when the connection terminals are formed of conductive strands mounted in parallel, independently of the geometry of the internal contacts of the module, but are of course reinforced when these internal contacts are also formed of conductive strands mounted in parallel. It is easy to understand that by playing on the relative importance of the width of the conductive strands and the width of the spaces separating them, especially if there are such conductive strands on the module, it is possible to define at will a compromise between electrical conduction and mechanical adhesion: a relatively large spacing corresponds to very good adhesion, while a higher surface density of conductive material leads to very good electrical conduction. The above has been explained in the case where the module is fixed to the cavity by means of an anisotropic adhesive, but it should be understood that similar advantages are found with other binding agents, such as conductive adhesives, if only with regard to the deformations of the compensation layers due to the presence of the connection terminals. It should be noted that when the second component has a constant height, it is no longer necessary to provide a step bordering the cavity, and the latter can have a simple shape, with a constant horizontal section over its entire depth. After the module has been fixed in the cavity, the card is complete with the physical point, and it no longer remains, in a known manner, to carry out personalization operations. The preceding figures represent geometries of connection terminals (and internal contacts) which are particularly simple, since these terminals (or these internal contacts) have the shape of a comb. But many other forms are possible according to the invention. This is how FIGS. 8A to 8C represent terminals 33, 33 ′ and 33 "each formed by a grid. Such a grid can be analyzed as being formed by conductive strands mounted in parallel (all the parallel strands at a given side of the grid) which cross at least one other strand arranged transversely. Insofar as the grids shown here are square, the "main" strands cross an equal number of other conductive strands. These three figures represent three grids whose mesh size is increasingly large, for the same width of the strands. It can be seen that in FIG. 8A, the surface fraction left free by the conductive strands is maximum, while in FIG. 8C this fraction is minimum. In FIG. 8A, the ratio between the mesh size and the width of the strands is of the order of 6.6 (mesh size of 0.80 mm for strands of 0.12 mm wide) while this ratio is of the order of 3.3 (mesh size of 0.40 mm for strands of 0.12 mm) in Figure 8B and of the order of 2.5 (mesh size of 0.30 mm for strands of 0.12 mm wide) for Figure 8C. We will choose the configuration of Figure 8A if we want to favor mechanical adhesion, or on the contrary that of Figure 8C if we want to favor electrical conduction, while we will choose that of Figure 8B if l '' we want both good adhesion and good electrical conduction. It can be noted that, in the examples given above, the width of the conductive strands is equal to the width of the tracks constituting the turns of the antenna. More generally, the width of these strands is preferably chosen between 120 microns and 250 microns. In a variant not shown, it is possible to provide conductive rings at the location of the crossings of strands, which reduces the risks of detachment. FIG. 9 represents a set of two connection terminals 43 and 44 both formed by two grids, the spacing between the strands taking, depending on the location, at least two different values: this spacing is here minimum at the ends and in the central part , while this spacing is maximum between the ends and the central part. We observe that almost all of these grids are contained within the maximum contour of the hole. In a variant not shown, the variation in the spacing (one can also speak of steps) is continuous between the zones of minimum spacing and the zones of maximum spacing. It is recalled that the grid is separated into two parts to take into account that it is necessary to establish contact with two internal contacts of the module. FIG. 10 shows another pair of connection terminals 53 and 54 formed from a square mesh grid with small spacing. The contours of the step are shown in this figure, and a white loop represents internal contacts 23 'or 24' of the module which are shaped as a ring. Here again, the inlay need not be precisely positioned in the card body to guarantee that there are many points of contact between this ring and the right or left portions of the grid. FIG. 11 represents another geometry of connection terminals 63 and 64, which differs from that of FIGS. 1 to 7 by the fact that, after digging of the cavity, the strands 63A and 64A, which are oriented towards the center of the cavity , extend between an external supply strand 63B or 64B and an internal strand 63C or 64C to which they are connected by their ends. In this figure also appear the internal contacts 73 and 74 of the module, each comprising, on the right or on the left, three discs 73A or 74A intended for connection to wires (not covered by the connection terminals) connected to two wings 73B or 74B located respectively to the right or to the left of these discs, as well as two end wings 73C or 74C arranged above and below these discs. It can be noted that the strands 63A or 64A are closer together opposite these wings than apart from them. It can be noted that these internal contacts can be analyzed as being formed by strands of conductive track separated by spaces at least as wide as these strands, and that some of these strands are mounted in parallel. FIG. 12 schematically represents an alternative embodiment in which the connection terminals 83 and 84 comprise strands are not rectilinear as in the examples considered above, but are closed in on themselves so as to form loops. Of course, in their production, these loops are dissociated in any appropriate manner so as to allow the terminals 83 and 84 to be isolated from one another. As before, they cooperate with internal contacts of a module jointly forming a ring between the internal and external edges of a step bordering the cavity. FIG. 13 represents another alternative embodiment in which the connection terminals 93 and 94 are no longer formed from straight or curved conductive strands but in a zig-zag fashion (with an appropriate dissociation to separate the terminals 93 and 94). It can be noted in the foregoing that the conductive zones are narrow with respect to their length, and that they are in practice surrounded by non-conductive zones which lend themselves well to good adhesion. By varying the widths of strands and / or the spaces separating them, it is possible to "specialize" different bonding zones of the module on the card by playing on the copper surface / total surface ratio. Thus, for example, the corners of the zones forming the connection terminals can be covered with little copper (we prefer adhesion) while in the middle zones we prefer electric conduction (more copper). The ratio between the surface of conductive material and the total surface of the bonding zone is advantageously less than 40%, preferably between 10% and 30%, advantageously between 10 and 20%.

Claims

CLAIMS 1. A microcircuit card comprising a card body in the thickness of which are provided terminals (3, 4, 33, 33 ', 33 ", 43, 44, 53, 54, 63, 64, 83, 84) of connection to a first component, and a second component (20) comprising this microcircuit (22) and internal contacts (23, 24, 23 ', 24', 73, 74) connected to these connection terminals by a mechanical connection material and electrical, characterized in that at least one of the connection zones formed by the connection terminals and the internal contacts has a geometry comprising conductive track strands (3A, 4B, 63A, 64A) separated by spaces at least as wide as these runways.

2. A microcircuit card according to claim 1, characterized in that the connection terminals have a geometry comprising such conductive strands separated by spaces at least as wide as these strands.

3. A microcircuit card according to claim 2, characterized in that the connection terminals are contiguous and the mechanical and electrical connection material is an anisotropic adhesive.

4. A microcircuit card according to claim 2 or claim 3, characterized in that the conductive strands are mounted in parallel.

5. A microcircuit card according to claim 4, characterized in that the strands have a thickness at most equal to 30 microns.

6. A microcircuit card according to claim 5, characterized in that the strands have a thickness at most equal to 15 microns.

7. A microcircuit card according to any one of claims 4 to 6, characterized in that these strands cross at least one other conductive strand transversely thereto.

8. A microcircuit card according to claim 7, characterized in that these strands cross this other strand at their ends.

9. Microcircuit card according to any one of claims 4 to 6, characterized in that these strands cross a plurality of other conductive strands so as to form a conductive grid (33, 33 ', 33 ", 43, 44, 53, 54).

10. A microcircuit card according to claim 9, characterized in that this conductive grid (43, 44) comprises meshes of at least two different sizes, defining zones having ^" different relationships between the strand surface and the total surface .

11. A microcircuit card according to any one of claims 1 to 6, characterized in that these strands close on them so as to form loops (83, 84).

12. A microcircuit card according to claim 11, characterized in that these loops intersect.

13. A microcircuit card according to any one of claims 4 to 6, characterized in that at least some of the strands have a periodic arrangement.

14. A microcircuit card according to any one of claims 1 to 13, characterized in that these conductive strands are distributed in two batches substantially symmetrical to one another (3A, 4A, 43, 44, 53, 54, 63, 64, 83, 84, 93, 94).

15. A microcircuit card according to any one of claims 1 to 14, characterized in that the second component is mounted in a cavity.

16. A microcircuit card according to claim 15, characterized in that this cavity opens out.

17. A microcircuit card according to claim 15 or claim 16, characterized in that these connection terminals include strands mounted in parallel and oriented towards the center of the cavity (63A, 64A).

18. A microcircuit card according to any one of claims 15 to 17, characterized in that two connection terminals are arranged opposite one another on either side of this cavity.

19. A microcircuit card according to any one of claims 15 to 18, characterized in that these connection terminals are arranged on steps bordering the cavity.

20. A microcircuit card according to any one of claims 1 to 19, characterized in that the internal contacts (23, 24, 73, 74) have a geometry comprising conductive strands

21. A microcircuit card according to claim 20, characterized in that these strands are electrically mounted in parallel.

22. Microcircuit card according to any one of claims 1 to 21, characterized in that both the connection terminals and the internal contacts comprise conductive strands which have different directions so as to cross.

23. A microcircuit card according to claim 22, characterized in that the total area of the internal contacts is less than the total area of the connection terminals.

24. A microcircuit card according to claim 22 or claim

23, characterized in that the strands of the connection terminals and those of the internal contacts face each other in zones whose overall surface is at least 1.8 mm ² .

25. A microcircuit card according to any one of claims 1 to 24, characterized in that the ratio between the surface of conductive material and the surface of underlying material is between 10% and 30%.

26. A microcircuit card according to claim 25, characterized in that this ratio is between 10% and 20% approximately.

27. Microcircuit card according to any one of claims 1 to 26, characterized in that the second component is a module comprising a support film on the internal face of which the microcircuit and the internal contacts are attached while on the external face external contacts are provided.

28. A microcircuit card according to any one of claims 1 to 27, characterized in that the component is an antenna (2) made in the thickness of the card body.

29. A microcircuit card according to claim 28, characterized in that the connection terminals include strands which have a width which is substantially equal to those of the tracks of the antenna.

30. A microcircuit card according to claim 28 or claim

29, characterized in that the width of the strands of the connection terminals is between 100 microns and 400 microns.

31. A microcircuit card according to any one of claims 28 to 30, characterized in that the width of the strands of the internal contacts is between 150 microns and 500 microns.