HK1149353B - Reinforced substrate for radiofrequency identification device and method for making same - Google Patents

Description

Enhanced rfid device support and method of making same

Technical Field

The present invention relates to radio frequency identification devices used for integration into objects such as security documents, and in particular to a support for an enhanced radio frequency identification device for a passport and a method of manufacturing the same.

Background

Contactless Radio Frequency Identification Devices (RFID) are increasingly used to identify people moving within a controlled proximity zone or from one zone to another. A contactless RFID device is a device made of an antenna and a chip connected to a terminal of the antenna. The chip is normally not powered and receives its energy through electromagnetic coupling between the antenna of the reader and the antenna of the RFID, information being exchanged between the RFID and the reader, in particular information stored in the chip relating to the identification of the holder of the object on which the RFID is placed and his/her authorization to enter into the controlled access area.

As such, the passport may include an RFID that identifies the passport holder. The chip memory contains information such as the identity of the passport holder, his/her country of birth, his/her nationality, visas of different countries visited, date of entry, activity restrictions, biometric elements, etc. RFID devices are typically incorporated into the bottom cover panel of a passport. The antenna is then printed on the reinforced back cover plate of the passport cover by using the ink loaded with conductive particles. Then, the chip is connected to the connection terminals of the antenna by gluing. A folded blank of the passport sheet is then attached to the back of the reinforced top cover sheet.

The RFID device may also be manufactured separately from the passport in order to then be added by gluing between, for example, the front and back white sheets of the passport. The RFID device, including the antenna and chip connected together, is then integrated with a paper, plastic, or other "inlay.

As an alternative to bare chips, RFID devices have also been developed by means of packaged chips, commonly referred to as integrated circuit modules. Recent developments in the miniaturization of these modules have in fact allowed them to be incorporated into passports without increasing the thickness or rigidity of the passport.

A problem with manufacturing RFID device supports integrated modules is the connection of the module to the antenna. In practice, conventional connections such as soldering, for example, for connecting a module to a copper antenna are not suitable for printed antennas. The connection of the module to the antenna is realized between the antenna connection point of the antenna support and the module contact point. Since this connection is made over a small area, it must be reliable and robust. In the case where the antenna is composed of conductive ink, such connection is made by a conductive adhesive. Making such a connection requires the following manufacturing steps:

-printing an antenna comprising contact points on a support;

-depositing a conductive adhesive dot on the antenna contact point;

-placing the electronic module on the spot of conductive adhesive;

the conductive adhesive is cross-linked by passing through an oven.

Then, a conventional lamination step of the layers constituting the card is carried out by generally thermoforming the upper and lower card bodies on both sides of the antenna support.

This connection has disadvantages. When the conductive adhesive is applied, a short circuit with the module may occur. Also, the conductive adhesive dots hardened in the crosslinking may crack the antenna contact points under the pressure applied during the lamination step or during impacts and shocks otherwise applied to the passport. The ultimate risk is thus to break the electrical contact between the antenna and the integrated circuit module and thereby ultimately to damage the rfid device.

Disclosure of Invention

The present invention therefore aims to remedy these drawbacks by providing a manufacturing method of support for rfid devices that makes it possible to guarantee a reliable connection between the integrated circuit module and the antenna.

It is a further object of the present invention to provide an identity booklet such as a passport incorporating such a radio frequency identification device, which does not have any visible indicia of the chip on the outside of the cover of the booklet.

The object of the present invention is therefore a method for manufacturing a Radio Frequency Identification Device (RFID) comprising an antenna and a chip connected to the antenna, the method comprising the steps of:

-printing an antenna comprising connection points on a paper or synthetic paper support;

-placing an adhesive dielectric material between connection points of the antenna;

-positioning an integrated circuit module on a support, the module comprising a contact area and a chip connected to the contact area within the package of the module, such that the contact area of the module is opposite to the connection point of the antenna;

-placing on the support a layer of thermoplastic material and a layer of paper or synthetic paper, both layers having cavities in the position of the encapsulation of the module; and

-laminating the three layers, i.e. the antenna support layer, the layer of thermoplastic material and the paper or synthetic paper layer, together so that the module is electrically connected to the antenna and the layers are brought together.

Drawings

The objects, objects and features of the present invention will become more apparent from the following description when read in conjunction with the accompanying drawings, in which,

figure 1 shows a cross-section of an electronic module,

figure 2 shows the layers making up the RFID device support before lamination,

fig. 3 shows a cross section of an RFID device support.

Detailed Description

According to fig. 1, the integrated circuit module comprises a chip 12, at least two connection regions 17 and 18. The connections between the chip and the connection regions 17 and 18 are made by very small wires or connection cables called "wire bonding" in english. The chip 12 and the wires are enclosed in a protective resin 14 based on a non-conductive, highly resistant material. The package 14 is in a sense a hard shell containing the chip and its wiring so that it is not easily damaged and is easier to handle. The package has a thickness between 200 and 240 μm. The module thus presents a flat surface on its upper side, corresponding to the upper part of the package 14, and contact areas 17 and 18 for connection with the circuit on its lower side. The contact regions 17 and 18 are made of a conductive material, such as aluminum, and their thickness is between 70 and 100 μm.

According to a first step of the present manufacturing method, an antenna is realized on the support layer 20. The antenna comprises a set of one or more coils. The coils are made by screen printing, flexographic offset printing, gravure printing, offset printing or ink jet printing using conductive inks of the epoxy type or based on conductive polymers, to which conductive particles such as, for example, silver or gold are added. The support layer 20 is made of a non-flowing material such as paper or synthetic paper. The paper is made of pulp micro-plant fibers and as a result has a fibrous structure. Paper core (du papier) tends to delaminate when subjected to shear stress, whereas non-fibrous synthetic papers have a microporous structure and have a low density. Similar to paper, synthetic paper simplifies the layering operation performed at temperatures on the order of 160 ℃, since it is stable at these temperatures; unlike thermoplastic materials such as PVC or PETGNo flow (fluent). The synthetic paper used consists of a non-oriented single layer of a polymer such as polyethylene or polypropylene with between 40% and 80% mineral addition. Through its microporous network, its composition is such that it has a density of 0.57g/cm³Low density of the order of (d). The thickness of the support layer is preferably between 140 and 180 μm.

The module 10 shown in fig. 2 is intended to be connected to the connection points of an antenna. In the present invention, only two connection points 31 and 32 are sufficient for connecting the modules. The connection points 31 and 32 are a continuum of the antenna, as a result of which they are in the extension of the coil of the antenna and are generally made of the same material as the antenna. The connection points are thus also made by screen printing, flexographic offset printing, gravure printing, offset printing or ink-jet printing with conductive inks based on the type of epoxy ink to which conductive particles such as, for example, silver or gold are added or based on conductive polymers. The thickness of the connection point is between 5 and 10 μm. The inks used in the manufacture of the connection points are flexible and non-elastic. Thus, the ink used for the antenna connection points may be different from the ink used to make the rest of the antenna.

The module shown in fig. 2 is glued to the antenna support layer 20 by means of an adhesive material 34 so that the contact areas 17 and 18 of the module are opposite the connection points 31 and 32 of the antenna. Once the ink making up the connection points has dried and the viscous material has been applied, the module is placed on the antenna support layer. The gluing of the modules on the antenna support layer has to hold and fix the modules in their position throughout the duration of the manufacturing process. The adhesive material used is an adhesive that secures the module to the support layer 20. Cyanoacrylate adhesive is used. It is also possible to use a film type "hot melt" adhesive used in the card and arranged under the module before insertion into the card. The glue is not used as an electrical connection between the support and the antenna.

Then, for the lamination step, the layers making up the RFID device support are placed on the antenna support. The first layer of thermoplastic material 22 is positioned directly on the antenna support layer 20. The thermoplastic material used for layer 22 is preferably polyvinyl chloride (PVC), but may also be a polyester (PET, PETG), polypropylene (PP), Polycarbonate (PC) or Acrylonitrile Butadiene Styrene (ABS) or Polyurethane (PU) film. The thickness of the layer 22 of thermoplastic material is between 100 and 160 μm. The layer 22 comprises a cavity 21 having a size close to the size of the planar surface of the upper part of the encapsulated part of the module. In this way, the edges of the cavity match (mate) with the edges of the encapsulated portion of the module. Thus, when the layer 22 is placed in position on the layer of the antenna support 20, the module 10 is located in the cavity 21. The second layer 24 is located on the first layer 22. Layer 24 is made of synthetic paper or paper as described for antenna support layer 20. Layer 24 also has a cavity 23 preferably having the same dimensions as cavity 21. When all layers are placed for the lamination step, the cavities 21 and 23 overlap.

The final step in the RFID device support manufacturing process consists in laminating together 3 layers, namely an antenna support layer 20, a layer 22 of thermoplastic material and a layer 24 of paper or synthetic paper. The lamination step consists in subjecting all the layers to a temperature increase up to 150 ℃ and a pressure increase up to 20 bar, then reducing the temperature and pressure, all according to a set of cycles of determined duration. The reduction of the ambient temperature is preferably done at a constant pressure and then the pressure is reduced. Upon lamination, the PVC of layer 22 fluidizes and captures most of the antenna and module. The pressure applied during lamination is perpendicular to the layers and thus to the contact areas 17 and 18.

Fig. 3 shows a cross section of the module and the 3 layers in the vicinity of the module after the lamination step. In the lamination step, the thickness of the three layers making up the RFID device support is reduced. In this way, the paper or synthetic paper layers 20 and 24 lose about 22% of their thickness. For example, a layer 20 or 24 having an initial thickness of 180 μm has a thickness of 140 μm after lamination. The layer 22 of thermoplastic material has reduced its thickness by 55%.

Pressure is applied to the entire module during lamination. The contact areas of the module press on the connection points of the antenna, resulting in a deformation of the connection points and the support layer 20. This deformation is in the form of a cavity (impression), the inner surface of which exactly matches the outer surface of the connecting zone. In this way, there is intimate contact at the largest contact surface between the connection area of the module and the conductive ink of the connection point 18. The material constituting the support layer 20 and the conductive ink of the connection points 18 are deformable and non-elastic, so that both materials do not tend to return to their original shape even when the pressure is released.

Also, upon lamination, the softened thermoplastic material of layer 22 completely matches the contour of the module and the inner surfaces of layers 20 and 24 on either side of layer 22. The thermoplastic material acts as an adhesive between layers 20 and 24 so that once hardened it adheres completely to the layers and the module. The two layers 20 and 24 on either side of the thermoplastic material layer are stressed by the pressure of lamination and the applied stress is maintained on the contact areas of the module, so that the electrical contact between the module and the antenna is permanent and reliable once the thermoplastic material of the layer 24 has hardened. The lamination step thus enables the module to be electrically connected to the antenna and the layers 20, 22 and 24 to be coalesced together. In this way, the positioning step of the module only enables the latter to be mechanically held between the antennas, in contrast to the mounting of bare chips by a method known as "flip-chip" in which the chip, once mounted between the antenna connection points, is electrically connected to the antennas. The module is electrically connected to the antenna by means of a method realized in combination with the materials used. In practice, the paper or synthetic paper layers 20 and 22 pinch the module at the location of the contact zone and the pinching effect is maintained by the layer 22 of thermoplastic material which hardens upon cooling.

The pressure exerted on the encapsulated and rigid portions of the module tends to further compress the portion of the support layer 20 directly beneath it. This effect tends to cause the RFID device support to have an equal thickness over its entire surface. Thus, the position of the module is not visible when inserted into the passport cover.

The manufacturing method according to the invention enables a reliable and robust radio frequency identification device to be obtained. This advantage is evident for the use of the device in a security document such as a passport. In fact, the passport sheets and the cover supporting the RFID device may be subjected to impacts from the imprint or visa attachment that would expose the electronic chip to a non-negligible risk of damage. In addition, the electrical connection between the module and the antenna is free of any rigid elements such as solder or conductive adhesive that make the module immobile with respect to the antenna, resulting in a stronger and more reliable electrical connection.

Claims (7)

1. A method for manufacturing a Radio Frequency Identification Device (RFID), the device comprising an antenna and a chip connected to the antenna, the method comprising the steps of:

printing an antenna comprising connection points on an antenna support layer made of paper or synthetic paper;

placing an adhesive dielectric material between the connection points of the antenna;

positioning an integrated circuit module on the antenna support layer, the module comprising a contact area and a chip connected to the contact area within a package of the module such that the contact area of the module is opposite to a connection point of the antenna;

placing a layer of thermoplastic material and a layer of paper or synthetic paper on said antenna support layer, both layers having cavities in the position of the encapsulation of the module; and

the three layers, i.e. the antenna support layer, the thermoplastic material layer and the paper or synthetic paper layer, are laminated together such that the module is electrically connected to the antenna, whereby the antenna support layer and the paper or synthetic paper layer pinch the module at the location of the contact area and the connection point of the antenna, wherein the pinch is maintained by the hardened thermoplastic material layer after the laminating step.

2. A method of manufacturing according to claim 1, wherein the shape of the cavities is such that the cavities match the shape of the package.

3. A method according to claim 1 or 2, wherein the cavities have the same dimensions.

4. A method according to claim 1 or 2, wherein, prior to the module positioning step, an adhesive dielectric material is placed on the antenna support layer between connection points of the antenna to hold the module in a fixed position relative to the antenna support layer.

5. The method of claim 4, wherein the tacky material disposed on the antenna support layer is a cyanoacrylate adhesive.

6. A method according to claim 1 or 2, wherein the ink used to make the antenna connection points is flexible.

7. A method according to claim 1 or 2, wherein the laminating step comprises subjecting all layers to a temperature increase up to 150 ℃ and a pressure increase up to 20 bar, and then reducing the temperature and pressure.