METHOD FOR MANUFACTURING CHIP CARDS AND CHIP CARD OBTAINED BY SAYENED METHOD

Description

[0001] The invention relates to the field of smart cards. Smart cards are well known to the public, who have multiple uses for them: payment cards, SIM cards for mobile phones, transport cards, identity cards, etc.

[0002] Smart cards comprise transmission means for transmitting data from an electronic chip (integrated circuit) to a card reader device (reading) or from this device to the card (writing). These transmission means can be "contact", "contactless" or dual-interface when they combine the two previous means. The invention makes it possible in particular to produce dual-interface smart cards. Dual-interface smart cards are called "dual" if the "contact" and "contactless" modes are managed by a single chip or "hybrid" if the "contact" and "contactless" modes are managed by two physically distinct chips.

[0003] Dual interface smart cards are generally made up of a rigid support made of plastic such as PVC, PVC / ABS, PET or polycarbonate constituting the main part of the card, in which are incorporated an electronic module and an antenna manufactured separately. The electronic module comprises a generally flexible printed circuit provided with an electronic chip and contact pads electrically connected to the chip and flush with the electronic module, on the surface of the support constituting the card, for a connection by electrical contact with a card reader device. Dual interface smart cards also comprise at least one antenna for transmitting data between the chip and a radiofrequency system allowing the reading or writing of data, without contact.

[0004] In the “dual” type smart cards of the prior art, the electronic module comprising the contacts and the chip, on the one hand, and the antenna possibly integrated into a support (“inlay” according to English terminology), on the other hand, are generally manufactured separately, then the antenna is connected to the module on which the chip is mounted and connected (an assembly of this type is described for example in patent application WO2013189757A1).

[0005] Document WO2013189757A1 discloses a method for connecting a smart card module with a card body comprising an antenna. U

[0006] Document US 2012 / 248201 A1 also discloses a method of manufacturing a hybrid smart card where the contacts between the antenna in the card body and the module are made by soldering. U

[0007] Document US 2008 / 283615A1 discloses a method of manufacturing a hybrid smart card using a module, the contact areas of the antenna of the card body are made in the form of meanders to increase the contact surface, a solder material is deposited on the meanders to contact with the connection pads of the module. U

[0008] The module and antenna may move slightly relative to each other during use, especially when the card is twisted. This can cause the connection between the antenna and the module, sometimes made by soldering, to be broken.

[0009] One aim of the invention is to make this connection more reliable.

[0010] This aim is at least partly achieved by a method of manufacturing a smart card according to independent claim 1.

[0011] This method also produces an antenna. The antenna has two ends. Optionally, the antenna is placed on an antenna support. The antenna is laminated between layers of plastic. Then, the module is placed in a cavity made in at least some of the layers of plastic.

[0012] Each end of the antenna is connected, using a solder material deposited on a connection portion, to a connection pad of the module. To do this, once the module is in place in the cavity, the solder material deposited on a connection portion is heated.

[0013] To make this connection more reliable, the connection pads are each made on an area covering a surface smaller than that of a connection portion covered with solder material.

[0014] Indeed, in this way, the connection pads are completely covered by the solder material, in particular after it has melted. They are therefore caught in the solder material after connection. Thus, the surface of the connection pads on which stresses generated during movements between the module and the card body can be applied is optimized and the stresses are essentially limited to the area corresponding to the surface of the connection pads. Possibly, parts of the connection pads can become detached from the module substrate, which gives them a certain freedom of movement, without breaking the connection between the module and the antenna.

[0015] This method also comprises one or other of the characteristics of claims 2 to 7 considered in isolation or in combination with one or more others.

[0016] The method according to the invention can be implemented continuously (“reel-to-reel” in English terminology).

[0017] According to another aspect, the invention relates to a smart card according to claim 9.

[0018] According to yet another aspect, the invention relates to a smart card module according to claim 11, in particular for producing a smart card according to claim 9. - This module comprises at least some of the characteristics set out in claims 1 to 8 and in particular, it may comprise a connection pad with at least one bar extending in a longitudinal direction over a length of between 1 and 7 mm (preferably, this length is between 1.5 and 3 mm, for example it is 2.5 mm), and the width of which is between 50 and 300 µm.

[0019] Optionally, in this smart card module, a connection pad comprises at least two bars whose longitudinal ends are curved and electrically connected.

[0020] Other characteristics and advantages of the invention will appear on reading the detailed description and the attached drawings in which: there figure 1 schematically represents in perspective a smart card conforming to an embodiment according to the invention: the figure 2 schematically represents in perspective and in an exploded manner, an example of stacking of constituent layers of the smart card represented on the figure 1 ; there figure 3 schematically represents in perspective and in an exploded manner, a variant of the embodiment of the smart card shown in the figure 2 ; there figure 4 schematically represents the smart card variant of the figure 3 , after milling a cavity and before inserting a module according to the invention into the cavity; the figure 5 schematically represents in perspective different stages of a method of manufacturing a connection unit usable in the embodiments illustrated by the figures 1 à 4 ; there figure 6 schematically represents in elevation, seen from its rear face, a first embodiment of a module in accordance with the invention; the figure 7 schematically represents the relationship between the respective surfaces of the portions of the connection pads covered with the solder material, on the one hand, and of the connection pads, on the other hand; figure 8 schematically represents in elevation, seen from its rear face, another embodiment of a module in accordance with the invention; and the figure 9 schematically represents in section a portion of a connection pad facing a drop of solder material.

[0021] In the figures, the same references designate identical or similar elements.

[0022] In this document the terms "front", "back", "above", "below", etc. are purely conventional and refer, where appropriate, to the orientations as shown in the figures.

[0023] The example of smart card 1 shown in the figure 1 comprises a card body 200 and a module 400. Such a smart card 1 can be manufactured using several methods.

[0024] According to an embodiment of the chip card manufacturing method according to the invention, shown in the figure 2 , the card body 200 is for example made up of a multi-layer complex comprising different layers of plastic material, such as (from bottom to top on the figure 2 ) : a lower layer 205, an antenna support 210, a connection unit 300, and an upper layer 220.

[0025] The lower layer 205 is, for example, a finishing layer (for printing, for example) and protection of the card 1. It is located under the antenna support 210. It is made of PVC and its thickness is, for example, 0.20 mm, before lamination, and 0.18 mm, after lamination. The thickness of this lower layer 205 is uniform.

[0026] The antenna support 210 comprises a PVC substrate 212, for example 0.43 mm thick, before lamination, and 0.40 mm thick, after lamination. A wire antenna 214 for example is deposited and fixed to the substrate 212 (for example embedded, by the technique known in English as “wire embedding”). This antenna 214 is formed of several wound turns and terminates with two ends 216, 218.

[0027] The connection unit 300 comprises a flexible film 310 with a first and a second main face (see also figure 5 ). A conductive layer 312 is laminated on one of these main faces. The substrate 310 is for example made of a material of the FR4 or VEP (glass-epoxy) type, 0.075 mm thick (and more generally less than or equal to 0.1 mm). The conductive layer 312 is for example made of a copper alloy in a 0.03 mm thick sheet. The flexible film 310 is therefore for example of the copper clad type.

[0028] The connection unit 300 has, for example, a length of 18 mm and a width of 4.5 mm. An opening 314 of 8 mm by 4 mm, for example, is cut substantially in the middle of the connection unit 300. The connection unit 300 comprises two connection pads 316. Each connection pad 316 comprises a first 317 and a second 319 portion, electrically connected to each other (see also figure 5 ). The first portion 317 has an essentially rectangular shape. The second portion 319 has, for example, a U shape extending around the openings 314, with the bottom of the U connected (connected) essentially to the middle of the first portion 317 considered in its longitudinal direction. According to another example not shown, each connection pad has an “H” shape with each of the parallel branches of the “H” corresponding respectively to a first or a second portion of the metallized zone, these first and second portions being connected by the middle branch.

[0029] As shown in the figure 5 , connection units 300 are produced (for example continuously, from reel to reel), from a flexible film 310. This flexible film 310 is cut (for example by punching) to form the openings 314 intended to receive the encapsulation resin of a module 400, as explained later. Drive notches are also cut. The conductive layer is then etched (for example using photolithography techniques) to form the connection pads 316 (two connection pads 316 per connection unit 300), with their first 317 and second 319 portions.

[0030] Solder material 350 is then deposited on each of the first 317 and second 319 portions of the connection pads 316, for example to a thickness of, for example, between 0.02 and 0.5 mm. The solder material 350 is for example made of a tin-bismuth alloy. The solder material 350 is then removed from the first portions 317. Finally, the connection units 300 are cut to be individualized. Alternatively, the solder material 350 is deposited more selectively, for example in the form of a drop of solder, only on each of the second portions 319 of the connection pads 316.The deposition of the solder material 350 on the second portions 319 (but as indicated above possibly also on the first portions 317) of the conductive layer of the connection pads 316 is carried out for example by dispensing, by screen printing or even by the so-called “wave” technology (this technology makes it possible to deposit solder material 350 on thicknesses of the order of 100 or 200 µm, or even less, and on small surfaces, such as 3x4 mm 2< for example). Each drop of solder material 350, once deposited on a second portion 319 and before the heating operation to carry out the soldering between the connection unit 300 and the module 400, forms a dome having a height of between 0.02 and 0.5 mm. Each drop of solder material 350, during heating, must come into contact with the connection pads 416 (see . figures 6 à 8 ). The wettability of the molten solder material 350 may possibly be sufficient to establish the connection, even in cases where a drop of solder material 350 would only be flush with the surface of the cavity 410 on which the module 400 is housed (see figures 2 And 4 ). However, insufficient or faulty contact due to insufficient wettability can be avoided by adapting the height of each drop of solder material 350 so that this height is greater than the distance which separates the top of the drop of solder material 350 from the connection pad 416 located under the module 400.

[0031] After placing a connection unit 300 (possibly glued) on or in the antenna support 210, the ends 216, 218 of the antenna 214 are connected (for example by thermocompression) to the first portions 317 of the connection pads 316. This assembly, consisting of the antenna 214 and the connection unit 300 on the support 210, can be covered with a layer of plastic material to form a structure which can be sold to be laminated with one or more other layers of plastic material in order to produce a smart card 1.

[0032] Returning to the description of the stacking of layers of plastic material, in relation to the figure 2 , it will be noted that the antenna support 210 may be composed of at least two sub-layers. In this case, the antenna is inserted for example between the lower sub-layer and the upper sub-layer. The upper sub-layer then comprises a cutout for receiving a connection unit 300.

[0033] The upper finishing and protective layer 220 is also, for example, made of PVC. It is 0.20 mm thick before lamination and 0.18 mm thick after lamination. This upper finishing and protective layer 220 has a cutout 222 corresponding to a cavity 410.

[0034] Alternatively, according to the variant illustrated by the figures 3 And 4 , rather than making a cut 222 in the different laminated layer(s) above the antenna support 210, the upper layer 220 is laminated with the antenna support 210 (and possibly the other constituent layers of the card body 200) without it being previously cut ( figure 3 ). Then, the cavity 410 is milled to reveal the second portions 319 of the connection pads before connecting and fixing the module 400 in the cavity 410. Advantageously, during the milling of the cavity 410, a portion of each drop of solder material 350 is removed, to ensure that the plastic material in which the milling is carried out will not prevent the surfaces to be welded from coming together, nor will the material forming the drops of molten solder material 350 from wetting the conductive tracks of the module 400 to which they are to be welded. The first portions 317 of the connection pads 316, to which the ends 216, 218 of the antenna 214 have been connected, are located outside the milled area and remain protected by the upper layer 220.

[0035] The lower layer 205 and the upper layer 220, as well as the antenna support 210, are not necessarily monolayers. Each of them may optionally consist of one or more layers, all laminated together in the finished board 1.

[0036] The total thickness of all layers 205-220, and therefore of card 1, is approximately 0.8 mm after lamination.

[0037] A module 400, called “double-sided”, is produced for example in a known manner on a substrate comprising contacts 412 on one face (called “contact face” or “front face”), and conductive tracks 414 (as well as an electronic chip not shown), on the other (called “rear face” or “bonding face”) (see figures 6 And 8). The fixing of the electronic chip on the substrate is carried out by at least one known technique such as die-attachment and its electrical connection to the conductive tracks 414 is carried out by at least one known technique such as flip-chip technology, wire-bonding, etc. The chip and its possible wire connections to the conductive tracks 414 are advantageously protected by encapsulation in a resin (globe top or dam&fill, corresponding to UV or thermal encapsulation). The chip being placed on the rear face of the substrate or in a cutout made in it, the encapsulation is carried out from this rear face and can form an excess thickness relative to it.

[0038] As shown, on the figures 6 And 7 , the conductive tracks 414 comprise connection pads 416. These connection pads 416 are used to solder the second portions 319 of the connection pads 316. Thus, the ends 216, 218 of the antenna 214 are themselves electrically connected to the first portions 317, connected to the second portions 319, which themselves are soldered to the connection pads 416 electrically connected on the rear face of the module 400 to the chip by the conductive tracks 414.

[0039] As schematically illustrated by the figure 7 , each connection pad 416 extends in an area 417 (delimited by dotted lines on the figure 7 ) covering a surface area smaller than that of the second portions 319 (on the figures 6 à 8 the second portions 319 are represented in the form of a hatched rectangle, but they can have other shapes and in particular the “U” shaped one shown in the previous figures). The zone 417 can be defined as being that which contains bars 418 and the conductive tracks which connect the bars 418 together. The bars 418 are elongated in a direction L essentially perpendicular to the largest side of the module 400, which is generally intended to be parallel to the length of the card 1. The longitudinal direction L is shown in the figures 1 à 4 .

[0040] In the embodiment shown in the figure 6 (which corresponds for example to a 400 module with eight contacts - called “8 pins”), there are three 418 bars.

[0041] Each bar 418 is relatively thin so that it can possibly detach from the substrate of the module 400 to absorb, without breaking, a significant stress. It has a width l for example between 50 µm and 300 µm. More particularly, it can have a width close to 100 µm. The fact of having a thin width allows them to possibly detach from the substrate 450 of the module 400.

[0042] The 418 bars have for example a length between 1 and 7 mm. The 418 bars shown on the figures 6 And 8 are essentially straight, but they could be wavy, sinusoidal, etc.

[0043] In order to be able to absorb the stresses as uniformly as possible, the bars 418 are essentially symmetrical with respect to a plane P perpendicular to the substrate of the module 400 and to the longitudinal direction L, and passing through the middle of the module 400.

[0044] The bars 418 meet at each of their longitudinal ends and are connected to the conductive tracks 414.

[0045] In order to reduce the stresses likely to accumulate at the ends of the bars 418, the ends of these bars terminate in curved portions 420. The radii of curvature of the curved portions make it possible to distribute the stresses over a greater length and a larger surface area.

[0046] In the embodiment shown in the figure 8 (which corresponds for example to a six-contact module 400 - called "6 pins"), the bars 418 are three in number and the curved portions 420 of the longitudinal ends of the bars are directed towards the inside of the module. In this embodiment, the two bars 418 furthest from the center of the module 400 have for example a width of 100 µm and the one closest to the center has a width of 150 µm. Their length is preferably between 1.5 and 3 mm; for example it is 2.5 mm.

[0047] To continue the manufacture of the smart card 1, the module 400 is placed in the cavity 410, with the solder material 350, arranged on each of the second portions 319 of the connection pads 316, opposite the connection pads 416.

[0048] The areas of the module 400 located at the level of the drops of solder material 350 are then heated, for example using a thermode, to melt the solder material 350 and solder the connection pads 316 to the connection pads 416 (This heating operation is possibly carried out at the same time as that consisting of heating areas of heat-reactivatable adhesive, very close to the drops of solder material allowing each module to be bonded in its cavity). By choosing a solder material 350 having a melting temperature of between 120°C and 230°C, and more preferably between 130 and 150°C, the operation of heating the solder material 350 can be carried out by applying, with a thermode for example, to an area of ​​the module 400, a temperature of between 120°C and 250°C.

[0049] Due to the thickness of the module 400 and the height of the dome of a drop of solder material 350, when the solder material melts, it wets the corresponding connection pad 416.

[0050] Furthermore, as shown in the figure 9 , the spaces between the bars 418 form grooves 422, delimited on the one hand by the sides corresponding to the thickness of the bars 418, and on the other hand, by the substrate 450 of the module 400. These grooves 422 make it possible to channel the solder material 350 and to prevent it from spreading widely outside the zone 417 in which a connection pad 416 is located.

[0051] Optionally, the solder between the connection pads 316 and the connection studs 416 may cover a surface area of ​​at least the order of 2mm 2< and is such that a sufficiently high tear-off force of the module 400 is obtained to meet the specifications of this type of product. The solder material 350 thus optionally makes it possible not only to establish an electrical connection between the connection pads 416 and the connection pads 316, but also to fix the module 400 in the cavity 410 without the aid of any other adhesive.

[0052] In the above, a smart card structure 1 has been described in which a connection unit is used to make the connection between the antenna 214 and the module 400. However, the invention also applies to a structure in which an antenna and connection pads are located on the same substrate (for example the antenna and the connection pads are etched on the same substrate which then forms an antenna support 210).

Claims

1. A method of manufacturing a chip card, comprising: - production of a smart card (1) module (400) comprising a substrate (450) having first and second main faces, with contacts (412) on the first face of the substrate, and conductive tracks (414) comprising connection pads (416) on the second face of the substrate, this module also being provided with an electronic chip (120) connected to at least some contacts (102) and to at least two conductive tracks (414) dedicated to an antenna connection, - making an antenna (214) with two ends (216, 218), - laminating the antenna (214) between layers of plastic (205, 220), and - positioning the module (400) in a cavity (410) formed in at least some of the plastic layers (220), - connection by means of a solder material deposited on a connection portion (319) of each of the ends (216, 218) of the antenna (214) with a connection pad (416) of the module (400), and heated, once the module (400) is in place in the cavity (410), characterised by the fact that the connection pads (416) are each produced on a zone (417) covering a surface area smaller than that of a connection portion (319), formed in a conductive layer and covered with soldering material (350).

2. A process as claimed in claim 1, wherein the solder material (350) consists of a material having a melting temperature of between 120°C and 230°C, and more preferably between 130°C and 150°C.

3. Method according to one of the preceding claims, in which at least one of the connection pads (416) comprising at least one bar (418) extending longitudinally in a direction (L) over a length of between 1 and 7 mm is produced.

4. Method according to one of the preceding claims, in which at least one of the connection pads (416) is produced comprising at least one bar (418), the width of which is between 50 and 300 µm.

5. Method according to one of the preceding claims, in which at least one of the connection pads (416) comprising at least one bar (418) extending longitudinally in a direction (L) essentially perpendicular to the length of the module (400) is produced.

6. Method according to one of the preceding claims, in which at least one of the connection pads (416) is produced comprising at least one bar (418), the ends of which are bent towards the inside of the module (400).

7. Method according to one of the preceding claims, in which at least one of the connection pads (416) comprising at least two bars (418) electrically connected by their longitudinal ends is produced.

8. Method according to one of the preceding claims, in which a connection unit (300) is produced and the ends of the antenna (214) are connected on the one hand to first portions (317) of the connection unit (300) and on the other hand a drop of soldering material (350) is deposited on second portions (319) of the connection unit (300) in order to produce a solder joint with each of the connection pads (416).

9. Smart card including : - an antenna (214) with two ends (216, 218), - plastic layers (205, 220) between which the antenna (214) is placed, and - a module (400) comprising a substrate (450) having first and second main faces, with contacts (412) on the first face of the substrate and conductive tracks (414) comprising connection pads (416) on the second face of the substrate, this module also being provided with an electronic chip connected to at least some contacts (412) and to at least two conductive tracks (414) dedicated to an antenna connection, the module (400) being placed in a cavity (410) formed in at least some of the plastic material layers (220), - a connection portion (319), connected to each of the ends (216, 218) of the antenna (214) and comprising solder material soldered to a connection pad (416) of the module (400), characterised in that the connection pads (416) each cover a zone (417) having a surface area smaller than that of a connection portion (319), formed in a conductive layer and covered with the solder material (350).

10. A smart card according to claim 9, in which the solder material (350) consists of a material having a melting temperature of between 120°C and 230°C, and more preferably between 130°C and 150°C.

11. Smart card module for producing a smart card according to one of claims 9 and 10, this module comprising a substrate (450) having a first and a second main face, with, on the first face of the substrate, contacts (412), and, on the second face of the substrate, conductive tracks (414) comprising connection pads (416), this module being intended to be provided with an electronic chip connected to at least some contacts (412) and to at least two conductive tracks (414) dedicated to an antenna connection, this module also being intended to be connected to a connection portion (319), formed in a conductive layer and connected to each of the ends (216, 218) of an antenna (214) and comprising soldering material, in which the connection pads (416) each cover an area (417) having a surface smaller than that of a connection portion (319) covered with the solder material (350) and at least one of the connection pads (416) comprises at least one bar (418) extending longitudinally in a direction (L) over a length of between 1 and 7 mm and whose width is between 50 and 300 µm.

12. A smart card module according to claim 11, in which the solder material (350) consists of a material having a melting temperature of between 120°C and 230°C, and more preferably between 130°C and 150°C.

13. A smart card module according to one of claims 11 or 12, in which a connection pad (416) comprises at least two bars (418), the longitudinal ends of which are bent and electrically connected.