EP2609544A1

EP2609544A1 - Polycarbonate radiofrequency identification device, and method for manufacturing same

Info

Publication number: EP2609544A1
Application number: EP11752255.7A
Authority: EP
Inventors: Carina Zambon
Original assignee: ASK SA
Current assignee: ASK SA
Priority date: 2010-07-12
Filing date: 2011-07-12
Publication date: 2013-07-03
Also published as: BR112013000823A2; CA2805201A1; CN103119616A; US20120175422A1; TW201218087A; KR20130095720A; US8616455B2; JP2013537663A; WO2012007659A1; MX2013000427A; FR2962579A1

Abstract

The invention relates to a method for manufacturing a radiofrequency identification device (RFID) including a planar and flexible substrate made of polycarbonate, which is provided with a conductive-ink antenna (14) completely embedded in the polycarbonate, and a chip or integrated circuit module (29) connected to the antenna. The antenna, which consists of a winding having a plurality of turns, includes an area in which turns intersect, wherein an insulating band made of a dielectric material separates the turns of the antenna at the intersecting area. The edges of the device are completely uniform, such that none of the lines of demarcation between the various layers are visible, thereby preventing any attempt to delaminate the device in the body thereof.

Description

Radio frequency identification device made of polycarbonate and its method of manufacture

Technical area

The present invention relates to the field of documents, valuables and security containing an electronic device for contactless data exchange and concerns in particular a radio frequency identification device (RFID) and its manufacturing method.

State of the art

A radiofrequency identification device (RFID) without contact is a device consisting mainly of an antenna embedded in a support of the device and a chip connected to the connection pads of the antenna. These devices allow the exchange of information with the outside by electromagnetic coupling at a distance and therefore without contact, between its antenna and a second antenna located in the associated reading device. These devices are used today in a large number of applications and in particular for the identification of people traveling in areas with controlled access or transit from one area to another. The device is generally formed on a flat and flexible support in the format of a bank card or in a format adapted to be inserted into a security document or value. Such RFID devices are commonly called "inlay". Generally, the chip is connected directly to the pads of the antenna by "flip-chip". However, the chip may also be encapsulated in a module to be better protected.

Information is exchanged between the RFID device and the reader and in particular the information stored in the chip relating to the identification of the owner of the object on which the device is located. RFID and its authorization to enter a controlled access area for example.

Currently, these RFID devices can be manufactured according to several manufacturing processes. We are interested here RFID devices whose antenna is made by printing on a thermoplastic support. One of the methods is to laminate together several layers of different material such as paper for the antenna support and thermoplastic for the upper and lower layers. The disadvantage of the RFID device obtained by such a method lies in the fact that it delaminates in its thickness and is therefore unsuitable for use over several years as may be the case for identity cards. On the other hand, the use of the same material for the three layers such as thermoplastic does not solve the problem of delamination and poses more problems at the time of laminating. Indeed, the lack of flexibility and elasticity of the superimposed layers together can crack the antenna and consequently break the electrical connection between the antenna and the chip during pressure rises. In addition, the rise in temperature during the lamination step generates deformations of the support which can also lead to cracking of the antenna aggravated by the large thickness at the crossing point of the turns due to the double thickness of material conductive forming turns and insulating material to separate and isolate the turns between them.

In addition, RFID devices made from wire antenna do not have the same disadvantages since the copper wire does not break under the effect of pressure but has a tendency to mold into the thermoplastic. In addition, because of its small thickness of the order of 25 μm and the fact that the copper wire is sheathed thus isolated, its use makes it possible to avoid the insulating layer between the superimposed turns and to obtain a overthickness at the crossing of the turns of the order of 50 μπι, so little constraining.

Presentation of the invention

This is why the object of the invention is to provide a method of manufacturing an RFID device whose antenna is produced by printing on a thermoplastic material, which solves the problems of cracking of the antenna printed at the time of printing. laminating step.

Another object of the invention is to provide an RFID device which does not present a risk of delamination over time.

The object of the invention is therefore a method of manufacturing a radio frequency identification device (RFID) comprising a planar substrate provided with an antenna and a chip connected to the antenna, the antenna formed by the winding of several turns comprises a crossing zone of the turns, an insulating strip of dielectric material separating the superposed antenna turns at the crossing, the method comprising the following steps:

a) forming the coil printing antenna, two conductive ink connection pads and an insulating strip of dielectric material at the crossover point of the turns, and heat - treating the substrate to bake said ink. ,

b) connect said chip to the support on the side of said antenna,

c) superposing a second layer on the substrate on the antenna side, this second layer comprising a first perforation centered on the chip and a second perforation centered on the insulating strip of the antenna crossing zone,

d) superimposing a third layer on the second layer,

e) rolling together the three layers. Brief description of the figures

The objects, objects and features of the invention will appear more clearly on reading the following description given with reference to the drawings in which:

FIG. 1 represents a front view of the layer supporting the radio frequency device,

FIG. 2 represents a sectional view along the axis A-A of the layer supporting the radiofrequency device of FIG. 1,

FIG. 3 represents a front view of the second layer of the RFID device support according to the invention,

FIG. 4 represents a sectional view of the radiofrequency device according to the invention.

In the figures, the elements represented are not in the real proportions.

Detailed description of the invention

In FIG. 1, a substrate 10 in the credit card format is shown seen from above. In the following description this substrate is designated antenna support. The support has an ISO format but it could have other dimensions, and for example be in the form of strips or boards with several support to be cut in ISO format. An underlayer 12 of thickness 5 μπι is deposited on the antenna support 10 on an area shown in gray in FIG. 1. For example, this underlayer is produced by printing an ink, a resin or a varnish. According to one embodiment, the underlayer 12 is made from a tinted transparent ink to facilitate visual identification. According to the preferred embodiment of the invention, the antenna support 10 is made of polycarbonate (PC). An antenna 11 comprising a winding of several turns, two connection pads 17 and 18 located at both ends of the winding and an electric bridge 13 is printed on the antenna support 10 on the sub-layer 12 and so that not leave the area defined by the sublayer. The size of the underlayer zone 12 is preferably slightly greater than the footprint of the antenna as can be seen in FIG. 1. The shape of the zone is thus determined directly by the shape of the antenna.

The turns of the antenna and the connection pads are produced by screen printing, flexo, gravure, offset or inkjet printing using epoxy ink conductive ink loaded with conductive particles such as, for example, silver. or gold or from a conductive polymer. According to another embodiment, the antenna is directly printed on the antenna support without underlayer 12. According to the two embodiments, with and without underlayer, the antenna is printed in several passes. The first pass is to print the two connection pads 17 and 18 of the antenna and the electric bridge 13, commonly called "cross-over". The second pass consists of printing an insulating strip 16 of dielectric material superimposed on the crossover. The third printing passage consists of printing the winding of the turns whose inner end 14 and the outer end 15 intersect the electrical bridge 13 so as to be electrically connected together. The insulating strip 16 thus makes it possible to obtain a crossing zone of the antenna where the electrical bridge 13 and the turns of the antenna intersect without any risk of a short circuit. The superposition of the crossed turns and the dielectric reaches a thickness between 70 and 75 μιη.

A perforation 19 is made in the antenna support between the connection pads 17 and 18. The perforation is performed by laser or with a punch. According to FIG. 2, an integrated circuit module 29 comprises a chip 25, at least two connection pads 23 and 24. The connection between the chip and the strips 23 and 24 is formed by conducting wires or connection cables 26, called commonly "wire bonding". The chip 25 and the wires are encapsulated in a protective resin 27 based on a resistant material and not conducting electricity. The encapsulation 27 (or "molding") is a kind of rigid shell that includes the chip and its wiring so as to make it less fragile and more manipulable. The encapsulation has a thickness of between 200 and 240 μπι. The module thus has on its upper face a flat surface corresponding to the upper part of one encapsulation 27 and on its lower face contact pads 23 and 24 intended to connect to a circuit. The tracks 23 and 24 are made of a conductive material such as aluminum and their thickness is between 70 and 100 μπι.

The module 29 is glued to the antenna support layer 10 by two pads of adhesive material 33 and 34 placed next to the antenna connection pads or straddling the antenna connection pads 17 and 18. module is positioned so that the connection pads 17 and 18 are opposite the contact pads 23 and 24 of the module and that the encapsulated portion of the module or encapsulation 27 is in the cavity 19. And in particular, a portion of the pads of connection 17 and 18 comes to bear against part of the contact pads 23 and 24 not covered with adhesive material. The adhesive material used for the pads 33 and 34 is an adhesive which fixes only the module to the support layer 10 and as this adhesive is not conductive it does not participate directly in the electrical connection between the module and the antenna. The adhesive used is epoxy type not loaded with conductive particles and heat-crosslinkable. The glue pads are placed on the support layer 10 to proximity of the antenna pads so that when the module 29 is placed in the cavity 19, the glue pads is crushed by a small portion of the contact pads of the module until another part of contact pads come into contact with the antenna pads. The glue pads then reach the same thickness as the antenna pads or substantially the same and come touching the antenna pads. The operation which consists of placing the module in the cavity is accompanied by a heating phase of the contact pads of the module which allows the adhesive to be cured. The glue pads harden under the effect of heat and thus maintain the areas of the module 23 and 24 in contact against the connection pads. This glue baking step is carried out locally by applying a heating resistor without pressure to the contact pads of the module.

The tight contact of the contact pads 23, 24 of the module and the connection pads 17, 18 of the antenna guarantees the reliability of the electrical connection. Thus, as soon as the module 29 is placed in the cavity 19, the electrical connection is made by the part of the contact pads 23, 24 of the module in direct contact with the connection pads 17 and 18 of the antenna. The support thus obtained is an antenna support provided with a module secured to the support and electrically connected to the antenna. The electrical connection has the advantage of being carried out without welding or adding material.

According to one embodiment of the invention, the connection pads 17 and 18 of the antenna have a concave or hollow shape or else recessed in the manner of a ring so that the pads of adhesive material 33 and 34 are placed inside the hollow of the concave shape or inside the recess. In a preferred embodiment of the invention, the antenna pads are U-shaped so that the pads of adhesive material are placed inside the U. According to Figure 3, a second layer 20 is shown from above. This second layer is a layer of polycarbonate (PC) with a thickness of between 50 and 60 μιη and of width and length identical to the first layer of the antenna support 10. In this layer two laser perforations 26 and 39 are produced. well using a cookie cutter. These two perforations are cavities through the entire thickness of the layer 20. The perforation 26 is located on the layer 20 so that when the layer 20 covers the layer 10 by overlapping edge to edge, the insulating strip 16 appears in the space left by the perforation 26. In this way, the perforation 26 is centered on the insulating strip. Similarly, the perforation 39 is located on the layer 20 so that when the layer 20 overlaps the layer 10 by overlapping edge to edge, the portion between the connection pads and a portion of the connection pads appears in the space left free by the perforation 39. In this way, the perforation 39 is centered on the module 29.

FIG. 4 shows in section the antenna support 10 along the axis AA of FIG. 1, the second layer 20 and a third layer 30. According to the manufacturing method of the device according to the invention, the layer 20 is positioned on the support 10 so that the external face of the module, therefore that including the contact pads of the module is housed in the perforation 39. A third layer 30 is also positioned on the layer 20. The layer 30 is a sheet of polycarbonate (PC) of identical dimensions to those of the other two layers and of thickness between 90 and 120 μιτι and preferably equal to 100 μπι. FIG. 5 shows in section the antenna support 10 along the axis BB of FIG. 2 and the second and third layers 20 and 30. During the step of positioning the layers 20 and 30 above the antenna support 10, the insulating strip 16 is housed in the perforation 26. The next step is to laminate layers 10, 20 and 30 together. The three layers thus undergo a temperature rise up to 180 ° C and a rise in pressure. During lamination, the intermediate layer 20 softens at lower temperatures than the lower and upper layers 10 and 30. Due to the pressure exerted during the lamination step, air trapped between the layers and in particular in the perforations 26 and 39 is removed and replaced by softened polycarbonate). In this way, the polycarbonate of the intermediate layer 20 fills the perforations during the lamination step. The layer 20 provided with these two perforations avoids and compensates the extra thicknesses due firstly to the crossing zone of the antenna and secondly to the module.

At the end of this lamination step, the three layers 10, 20 and 30 are welded together as can be seen in FIG. 6. Once welded together, the polycarbonate layers are no longer distinguished in the thickness RFID device obtained so that there is no possibility of delamination in the thickness. The antenna 11 comprising the turns, the two connection pads 17 and 18 and the electrical bridge 13 is completely embedded in the polycarbonate of the three layers 10, 20 and 30 welded together. The edges of the RFID device according to the invention are uniform and do not have parallel demarcation lines at the upper edges 62 and lower 61 which could assume an assembly of several layers together; which makes it impossible to attempt delamination of the device in its thickness.

According to an alternative embodiment of the invention, the integrated circuit module is replaced by a bare chip of the type of the chip 25 encapsulated in the module. According to this variant not shown in the figures, the steps of producing the antenna and the step of laminating the layers together are the same as for the embodiment described with an integrated circuit module. However, the perforation 19 is not necessary in the case of a chip. The perforations 26 and 39 are made in the same way in the layer 20; the perforation 39 being centered on the chip. The connection of the chip to the antenna is carried out according to a method of the type described in FR2 826 153 of the Applicant. Adhesive dielectric material is deposited on the antenna support 10 between the connection pads 17, 18 of the antenna and the chip is positioned on the antenna support so that the contacts of the chip are against the connection pads of the antenna. The adhesive material is then heat-treated to cure.

In this embodiment, the pressure exerted on the chip when it is connected to the antenna enables the contacts of the chip, commonly known as "bumps", to penetrate into the connecting terminals of the antenna which deform and thus guarantee better connection between the chip and the antenna.

The RFID device according to the invention forms a plan support that can be integrated into a security document such as an identity card, an identity book, a driver's license, an access card, etc.

The RFID device according to the invention has a thickness of between 0.38 and 0.41 mm and has the advantage of supporting laser etching.

Claims

A method of manufacturing a radio frequency identification device (RFID) comprising a planar substrate provided with an antenna (14) and a chip (25) connected to the antenna, said antenna formed by the winding of a plurality of turns (11) comprises a crossing zone of the turns, an insulating strip (16) of dielectric material separating the superposed antenna turns at the crossing, the method comprising the following steps:

a) forming the coil - printing antenna, two conducting ink pads (17, 18) and an insulating strip (16) of dielectric material at the crossing point of the turns, and performing a treatment thermal said support to bake said ink,

b) connecting said chip (25) to said support (10) on the side of said antenna (14),

c) superimposing a second layer (20) on said substrate on the antenna side, said second layer comprising a first perforation (39) centered on the chip and a second perforation (26) centered on said insulating strip (16) of the crossing zone of the antenna, d) superimposing a third layer (30) on the second layer,

e) laminating together the three layers (10, 20, 30).

2. Method according to claim 1, wherein said layers (10, 20, 30) are of polycarbonate (PC).

3. Method according to one of claims 1 or 2, wherein step b) comprises the following steps:

bl) depositing adhesive dielectric material between said connection pads (17, 18) of the antenna, b2) positioning said chip (25) so that the contacts of the chip are against said connection pads (17, 18) of the antenna,

b3) heat treating said adhesive material so as to cure it.

4. Method according to one of claims 1 or 2, wherein step b) comprises the following steps:

bl) perforating (19) between said connection pads (17 and 18) of the antenna,

b2) depositing adhesive dielectric material (33, 34) on a portion of said connection pads (17, 18) of the antenna,

b3) positioning said encapsulated chip in a module (29) so that said contacts (23, 24) of said module (29) are against said connection pads (17, 18) of the antenna and that encapsulation ( 27) of the module either in said cavity,

b4) heat treating said adhesive material (33, 34) so as to cure it.

5. The method of claim 4, wherein the connection pads (17, 18) of the antenna are U-shaped.

6. The method of claim 1, wherein said perforations (19, 26, 39) are performed by laser or with a punch before the superposition of layers between them.

The method of claim 4 or 5, wherein the adhesive material (33,34) is a heat-curable epoxy type adhesive.

8. Method according to one of claims 2 to 8, wherein the polycarbonate layers (10, 20, 30) is transparent.

9. Method according to one of the preceding claims, wherein step a) comprises the following steps:

al) printing an underlayer (12) of a predominantly varnished material on a predetermined area on said antenna support substrate (10), said area corresponding to the antenna footprint or being slightly larger than thereof,

a2) printing the antenna on said underlayer (12).

The method of claim 9, wherein said underlayer (12) is made from a tinted transparent ink to facilitate visual registration.

11. Radio frequency identification device (RFID) obtained according to one of the preceding claims, comprising a plane and flexible polycarbonate substrate provided with an antenna (14) of conductive ink completely embedded in the polycarbonate and a chip ( 25) or an integrated circuit module (29) connected to the antenna, said antenna formed by the winding of several turns comprises a crossing zone of the turns, an insulating strip of dielectric material (16) separating the turns of the antenna superimposed at the crossing zone, the edges of the device being completely uniform so that no demarcation lines of the different layers between them is visible thus preventing any attempt to delaminate the device in its thickness.