CN1292129A - Electronic device with contactless electronic memory, and method for making same - Google Patents

Abstract

The invention relates to a contactless electronic device(10)such as a card, a label, a ticket or a token, comprising at least an electronic microcircuit(20)arranged in the thickness of a rigid or semirigid support and comprising pads(26)connected to an interface antenna(24)arranged in the thickness of the support, the latter comprising at least two opposite, lower(12)and upper(14), protective sheets. The invention is characterized in that it comprises a stack: of a lower protective sheet(12)whereof the inner face(22)bears at least one electronic microcircuit and at least one interface antenna(24); of an intermediate bonding sheet(14)whereof the two opposite faces lower and upper are provided with adhesive; and of an upper protective sheet(16).

Description

An electronic device with a contactless electronic memory and its manufacturing method

The invention relates to a method of making a thin, bendable, contactless electronic device (10) - such as a card, label, ticket or tag - comprising at least one microelectronic circuit (20), the microelectronic The electronic circuit is arranged in a support with pins connected to an interface antenna (24) also arranged in the support, and the support contains at least two opposing protective sheets - a bottom sheet (12) and a top sheet (16), the The method comprises the following sequential steps.

There are many examples of these electronic devices, which are commonly referred to as smart cards, either rigid cards with a support made of plastic, or tags - also known as "electronic tags", which are used to mark single-use bulk A consumer product, that is to say its purpose is to stick on the product once, and it is basically just a piece of paper.

Therefore, there is a need for an electronic device of the above-mentioned type, such as a contactless smart card, which is very thin (for example, its thickness may be less than about 400 microns, or even 280 microns), and which can be bent, or even folded in half, and which can also be used multiple times, And its thickness and cost are very low, so it can be used in many applications that rely on chips with electronic memory, which is not currently possible due to the cost and/or thickness of the support. memory cards, tags, tickets or tags.

At the same time, there is a need for stronger devices that can be handled without care, or that can even be folded in half without compromising their functionality. An example of this is a subway ticket.

In addition, there is a need for contactless devices that are very thin and whose excellent surface quality allows them to be used as supports for high-quality printing. Examples of this are mainly playing cards or identification cards.

To this end, the invention provides a method of making an electronic device of the above-mentioned type, which comprises the following successive steps:

a) Make a bottom protection sheet by the following method:

a1) placing at least one microelectronic circuit on the inner surface of the negative;

a2) specifically making at least one interface antenna on the inner surface of the film by screen printing;

a3) electrically connecting the pins of the microelectronic circuit to the interface antenna;

b) making a laminate by superimposing an intermediate adhesive layer and a top protective sheet on the bottom protective sheet, wherein the upper and lower opposite sides of the intermediate layer are glued;

c) Fit the three superimposed layers together by compressing them. Other features of the method according to the invention:

- assembly step c) includes a hot rolling operation;

- a notch in the middle adhesive layer perpendicular to the microelectronic circuit;

-The middle adhesive layer is a hot-melt adhesive layer;

-The middle adhesive layer is a layer of paper, and a layer of hot-melt glue is applied on the upper and lower opposite sides;

- During step a) of making the bottom protection sheet, sequentially perform operations a1), a2) and a3);

- At least one protective sheet is made of paper;

- The method comprises a supplementary step of printing on one and/or the other of the outer surfaces of the upper and lower protective sheets of the support. Preferably, printing is performed before antenna and/or chip mounting;

- the method includes the additional step of cutting such electronic devices along the perimeter of a given card, tag, ticket or sign;

- Simultaneous fabrication of several electronic components with rolls of protective sheets and adhesive layers and separation in a supplementary cutting step.

The invention also relates to a contactless electronic device of the above-mentioned type, characterized in that it comprises a stack of:

- an underlying protective sheet, the inner surface of which carries at least one microelectronic circuit and at least one interface antenna;

- an intermediate adhesive layer, the upper and lower opposite sides of which are coated with glue;

- and a top protection sheet.

Other features of the device according to the invention:

- the middle adhesive layer has a notch perpendicular to the microelectronic circuit;

-The middle adhesive layer is a hot-melt adhesive layer;

-The middle adhesive layer is a layer of paper, and its upper and lower sides are coated with a layer of hot melt glue;

- At least one protective sheet is made of paper;

- the thickness of the device is less than 400 microns, or even 280 microns;

- The thickness of the layer carrying the antenna and the microelectronic circuit (chip) is less than or equal to 75 microns.

Other characteristics or advantages of the present invention can be known when reading the following detailed description, and the accompanying drawings can be used as a reference for understanding the present invention, wherein:

- Accompanying drawing 1 schematically shows a longitudinal section of a first embodiment of a smart card manufactured according to the method according to the invention, also depicting a laminate consisting of three layers before the hot rolling operation;

- Accompanying drawing 2 is similar to accompanying drawing 1, and it has shown the second embodiment of the smart card made according to the method of the present invention;

- Figures 3A to 3C schematically illustrate three operations for producing a bottom layer of protective paper for use in electronic devices produced in accordance with the present invention;

- Figure 4 schematically shows the manufacture of a laminate obtained by superimposing the three layers that make up the support of the smart card (produced according to the method described in the invention).

In the following description, the same reference numerals represent the same, similar or analogous elements, and, for the convenience of explanation, in the description and claims, terms such as bottom, top, and vertical in the drawings are used, but They are not limiting.

By definition, bendable refers to the mechanical properties of playing cards.

The product of the present invention is designed to be used like a subway ticket, and its sending and receiving functions will not be damaged when it is rolled up or even folded by hand.

Figure 1 depicts a smart card comprising a vertical lamination with three layers 12 , 14 and 16 .

The backsheet 12 is a first paper sheet having a thickness of, for example, 75 microns and made of "Maine" paper sold by the Arjo-Wiggins Company.

The paper backsheet 12 forms the bottom protective sheet of the card 10, while the topsheet 16 having the same construction and thickness as the backsheet 12 forms the top protective paper sheet of the card 10.

Intermediate layer 14 is then used for mutually bonding bottom sheet 12 and top sheet 16, and in this first embodiment, intermediate layer is a thin sheet or film that is coated with hot-melt glue, also can be referred to as hot-melt layer, and its thickness is 100 µm, courtesy of Polyconcept. The hot melt layer has the following advantages: it is soft at room temperature and does not damage the chip during lamination.

According to the characteristics of the present invention, when the intermediate adhesive layer 14 is as hard as paper, it can have a vertical arrangement and be placed on the microelectronic circuit 20 or chip perpendicular to the inner surface 22 of the backsheet 12 if desired. windows 18.

The microelectronic circuit 20 is connected to an interface antenna 24 which, according to known techniques, can be screen-printed on the upper surface 22, for example, with the aid of a silver-based conductive ink, such as ink E520 from Dupont de Nemours.

The microelectronic circuit 20 may be, for example, a "chip Mifare Amtel AT 8100", the thickness of which is reduced to, for example, 70 microns. It can be fixed on the surface 22 by, for example, gluing.

The electrical connection of the microelectronic circuit or electronic module 20 to the interface antenna 24 is preferably achieved using conductive particles 26 , such as the glue sold under the name "Ablestick Silver Glue", according to known techniques.

The second embodiment shown in FIG. 2 differs from the first embodiment just described, which only illustrates the structure of the intermediate adhesive layer 14 .

This is because, here adhesive layer 14 comprises an intermediate paper layer 14A, and its front and back two outer surfaces all coated one deck hot-melt glue 14B, like this, the composite layer that forms intermediate adhesive layer 14 just can be with accompanying drawing The adhesive layer 14 in 1-comprising only one layer of hot-melt adhesive film-is also inserted between the backsheet 12 and the topsheet 16.

The following description gives an example of a method of making the card 10 shown in FIG. 1 or FIG. 2 .

In order to obtain an industrial method for the mass production of electronic devices such as the card 10, several devices need to be fabricated simultaneously and/or one after the other, especially when making the three layers 12, 14 and 16 using continuous strips. or volume.

Firstly, the bottom protective paper sheet 12 will be produced.

For this purpose, as shown in FIG. 3A , the starting point is the paper sheet 12 , on the upper surface 22 of which the microelectronic circuit or module 20 is glued, as is the case for each electronic device.

Next, as shown in FIG. 3B , antenna 24 is fabricated, preferably by screen printing on upper surface 22 . Alternatively, the antenna can be made before fixing and connecting the modules.

Finally, as shown in FIG. 3C , the electrical connection or coupling between the microelectronic circuit 20 and the antenna 24 is realized by depositing conductive particles 26 .

Thus, at the end of the operation shown in Figure 3C, there is a strip or roll of paper negative 12 which must next be laminated with the other layers 14 and 16.

An illustration of the next step is shown in accompanying drawing 4, which schematically depicts the lamination of the backsheet 12, the intermediate adhesive layer 14 and the top protective paper sheet 16 in an exploded perspective view, wherein the backsheet 12 has been prepared in advance , where appropriate on the intermediate layer 14, windows or cutouts 18 have also been made in advance.

It follows, therefore, that in a next step (not shown in this step) a laminate or sandwich structure is made by thermocompression assembling the three superimposed layers 12, 14 and 16, for example in a heated lamination operation. That is to say, the intermediate layer 14 ( FIG. 1 ) is formed within the laminate or the adhesive layer 14B is formed on the intermediate adhesive layer 14 ( FIG. 2 ) at a temperature that causes the hot melt adhesive to melt.

This rolling operation, also known as lamination, turns the three layers into one stack, also reducing the overall thickness of the electronic device to less than or equal to 260 microns.

Window 18 perpendicular to each microelectronic circuit 20 protects the microelectronic circuit from damage during rolling operations.

To ensure that the window 18 matches the microelectronic circuit 20, of course means is required to position the rolls or strips of layers 12 and 14.

At the end of the assembly step by hot rolling, the electronic device on the strip or roll, whether it be a card, label, ticket or tag, must be cut using known methods, for example according to the punching technique.

It is of course possible to print on either or both surfaces outside the protective paper under the bottom 12 or on the top 16 at any step before or after cutting the electronic device.

Therefore, the present invention enables electronic devices with contactless electronic memory to be reduced in cost and thickness, and it may replace other products provided with identification means, such as flexible tickets with magnetic strips or barcodes, etc. , At the same time, these new electronic devices are also biodegradable.

The present invention is not limited to the embodiments and methods described above.

Different operations make it possible to make the bottom protective paper sheet 12 with the microelectronic circuit 20 and the antenna 24 using other known processes, for example, the antenna can be prepared first, and then the conductive contact pins of the microelectronic circuit are positioned toward the upward surface 22, and directly placed on the conductive part of the antenna 24 (flip-chip method), like this, the connection of the microelectronic circuit is automatically realized.

The connection of microelectronic circuit 20 and antenna 24 can also be accomplished using micro-wire connections or soldering techniques ("wire bonds"), but such connections are fragile and relatively thick.

Regardless of the configuration of the intermediate adhesive layer 14, the presence of the hot melt adhesive avoids reliance on "encapsulation" techniques - which involve the use of resin to protect the microelectronic circuit 20 and its connections.

The nature of the hot-melt glue used can also be slightly tacky when cold to the touch, so that a stack with three layers can be preassembled together prior to the hot rolling operation.

The protective sheets (12, 16) and the layer 14 can also be made of polymers, mainly polymers (PVC, PE, PP) usually used in the field of smart cards.

These layers can also be made of cellulose mixed with polymers, which can improve certain properties (watertightness, mechanical strength, etc.).

The present invention requires a combination of several parameters. In addition to chiplets (less than 70 microns) and thin protective sheets, the entire device needs to be assembled, preferably using an intermediate heat-melt or heat-sealing layer. Due to the softness of this layer when it cools, it has the advantage that the silicon chip can be brought into direct contact with it during the rolling process without damaging the chip. From this point of view, the notch on the intermediate layer is not necessary.

Hot rolling with a smooth board can improve the initial surface condition of the protective sheet.

Paper sheets can also be used, which are more economical than the previously mentioned polymer sheets.

Fabrication of the antenna is preferably by screen printing. This is because many tests of etching on sheets of paper (aluminum, copper, etc.) have shown that the chemical changes cause the paper to wrinkle and yellow the paper.

In addition, it is not possible to print the protective sheet before making the antenna with screen printing (the advantage is that the printing quality can be checked to avoid waste products before installing the chip). Another problem can arise if the screen printing technique is not used on thin protective sheets, especially paper or polymer boards, if extreme care is not taken. Here's the problem: Drying of the ink can cause the surface to wrinkle. This problem and its solution are described in patent application FR 97/13734, 3.10.97. They are included as a reference in the method of the invention to produce devices with superior surface quality (wrinkle-free).

According to the above application, the advantage of screen printing is that it produces antenna lines with precise shape and good conductive quality (silver particles). According to the method described in the aforementioned application, if the ink is applied to the polymer and allowed to partially dry, the device can be folded in half by hand multiple times, say five times, without damaging the antenna.

In addition, compared with the antenna made by etching, the silver-mixed antenna made by screen printing is cheaper and more convenient if it is connected to the chip through the following connection components.

Preferably, the connection components are either conductive grains mixed with silver, at this time the chip is fixed with the front facing up, or conductive glue dots, at this time the chip is fixed upside down (flip-chip method).

These connections are thinner and more resistant to mechanical stress than soldered metal wire (wire bond) connection types.

Claims (15)

1. A method of making a thin, bendable and foldable contactless electronic device (10), such as a card, label, ticket or tag, comprising at least one microelectronic circuit (20), the microelectronic circuit arrangement In the support body, the pins it has are connected to the interface antenna (24) that is also arranged in the support body, and the support body contains at least two relative protection sheets, namely a bottom sheet (12) and a top sheet (16), the method includes The following consecutive steps: a) make a bottom protection sheet (12), by: a1) placing at least one microelectronic circuit (20) on the inner surface (22) of the paper negative; a2) making at least one interface antenna (24) on the inner surface (22) of the film (12) by screen printing; a3) electrically connecting (26) the pins of the microelectronic circuit (20) to the interface antenna (24); b) A laminate is produced by superimposing an intermediate adhesive layer (14, 14A, 14B) and a top protective sheet (16) on the bottom protective paper sheet (12), wherein the upper and lower opposite sides of the intermediate layer are glued; c) Assembly of the three superimposed layers (12, 14, 16) by thermocompression. 2. 2. Method according to claim 1, characterized in that the assembling step c) consists of a hot rolling operation. 3. The method as claimed in one of the preceding claims, characterized in that the intermediate adhesive layer (14) has a recess (18) perpendicular to the microelectronic circuit (20). 4. The method according to one of claims 1 to 3, characterized in that the intermediate adhesive layer (14) is a hot melt adhesive layer. 5. The method according to one of claims 1 to 3, characterized in that the intermediate adhesive layer (14) is a layer of paper (14A) with a layer of hot-melt glue (14B) applied to its upper and lower opposite sides. 6. The method according to one of the preceding claims, characterized in that, during step a) of producing the bottom protective sheet (12), operations a1), a2) and a3) are performed sequentially. 7. A method according to one of the preceding claims, characterized in that it comprises a supplementary step of printing on one and/or the other of the outer surfaces of the bottom (12) and top (16) protective sheets of the support. 8. The method according to one of the preceding claims, characterized in that it includes a supplementary step of cutting such electronic devices (10) along the circumference of a given card, label, ticket or plate. 9. The method according to the preceding claim, characterized in that several electronic components (10) are produced simultaneously with the roll of protective sheet and adhesive layer and that the electronic components are separated in a supplementary cutting step. 10. Method according to the preceding claim, characterized in that at least one protective sheet is made of paper. 11. A contactless electronic device (10), such as a card, tag, ticket or tag, comprising at least one microelectronic circuit (20), arranged in a bendable support body, having pins (26 ) is connected to the interface antenna (24) also arranged in the support body, and the support body contains at least two opposite protective sheets, namely the bottom sheet (12) and the top sheet (14), is characterized in that it includes a thickness less than 400 microns A collapsible overlay for that contains: - an underlying protective sheet (12), the inner surface (22) of which carries at least one microelectronic circuit and at least one interface antenna (24); - an intermediate adhesive layer (14) coated with glue on its upper and lower opposite sides; - and a top protection sheet (16). 12. Electronic device according to the preceding claim, characterized in that the intermediate adhesive layer (14) has a recess (18) perpendicular to the microelectronic circuit (20). 13. The electronic device according to one of claims 11 or 12, characterized in that the intermediate adhesive layer (14) is a hot-melt adhesive layer. 14. The electronic device according to one of claims 11 or 12, characterized in that the intermediate adhesive layer (14) is a layer of paper (14A), and a layer of hot melt adhesive (14B) is coated on the upper and lower opposite surfaces. 15. Electronic device according to one of claims 11 or 12, characterized in that at least one protective sheet is made of paper.

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