DE19641406C2 - Smart card - Google Patents

Description

The invention relates to a chip card with an integrated Circuit according to the preamble of patent claim 1.

Chip cards are generally known, in which data on contacts envisaged on the chip card and / or can be read out. A data transfer is also non-contact via an inductive provided in the card Antenna element possible. In addition, chip cards are knows both contact points for contact-related data transmission as well as one or more antenna elements for have contactless data transmission.

In the case of contactless data transmission using an indukti ven elements must have a sufficient magnetic flux density in the Antenna element must be guaranteed so that sufficient resolution bare signals can be sent or received.

The magnetic flux density can be increased by increasing the exciter current or by increasing the number of turns of an antenna element strengthened. Both are in practice, however Set limits.

The generic DE 44 16 697 A1 is a data carrier with an integrated circuit, d. H. a Chip card, a flat coil being provided in the card body is to exchange wireless information between card and a terminal, d. H. the environment.

Specifically, a decoupling from module is proposed there and coil to realize to save manufacturing costs and to achieve the required quality assurance. The be written coil can be punched out of metal foil or from a  electrically conductive coated plastic film etched and on the card body layer are glued on. Continues on referred to a known hot stamping process.

US 5,408,243 discloses a method of making a flat, flexible antenna. The antenna described there should for example in a card or other flexible Carriers are brought in to enable data transmission in accordance with Art of a transponder.

To improve the transmission properties of the antenna, it is proposed that the antenna turns on an antenna to bring up the core, which has special properties be shown. Specifically for the manufacture of the antennas core uses soft magnetic material, which is present in particles and overall a high permeate bility. The powdery material used is mixed with a synthetic resin, whereby the curing occurs under a magnetic field, causing the can align magnetic particles under the influence of a field.

The chip card described in DE 195 00 925 A1 contactless data transfer goes on difficulties of Surface design, d. H. the loss of quality due to a deformed printed image. To reduce reject costs there is proposed a separate one in the card body Install transmission module, which is an antenna in the form at least one coil and / or in the form of electrically conductive Has layers.

DE 31 43 915 A1 discloses an identity card, which both an optically readable personalization field as well as one contactless transmission device with a receiving antenna includes. The receiving antenna there can also act as antennas be formed array, a transmitter is additionally provided is.  

DE 44 28 732 C1 is a multi-layer chip card coil for contactless chip cards described, with a closer explained special method of folding a film terials a stack of coils is possible so that an overall improvement in the inductance can be achieved.

From the above, it is therefore an object of the invention Transmission properties of chip cards with an integrier circuit and one implemented in the card body To improve the antenna despite further miniaturization, so that the reliability in handling such cards improved overall.

The object of the invention is achieved with a Subject according to the features of claim 1.

Advantageous further developments are specified in the subclaims ben.

The basic idea of the present invention is to provide an induction-increasing element whose relative permeability is µ _r <1 and which interacts with the antenna element.

In general:

B = µ _r .H

where H is the magnetic field strength, µ _{r is} the relative permeability and B is the magnetic flux density. In the case of a coil of length l with n turns, the result is

According to the Faraday law of induction, a voltage is induced in a coil when the magnetic flux ϕ = BA _S , which passes through the coil with n turns with a cross-sectional area A _S , changes in a time period Δt by Δϕ. The following applies:

U _ind = n.ϕ (2)

= n. (BA _S ).
= n. (BA _S + BA _S )
= nBA _S + nBA _S (3)

The total induced voltage is therefore the sum of the induced voltages, caused by the change in the cross-sectional area A _S at constant magnetic flux density and by the change in magnetic flux density B at constant cross-sectional area. Substituting formula (1) in formula (3) results in

To achieve high induced voltages at high frequencies zen, soft magnetic materials are particularly suitable. Soft magnetic materials are characterized by a high re relative permeability, low coercive force and simply um magnetisability. The enclosed area in the hy steresis curve of these materials is small and thus the in the form of heat loss of energy.

At high frequencies, however, the magnetic permeability is reduced by induced eddy currents. The passage of the magnetic field through the material is hindered in this case. This can be remedied by reducing the material thickness and increasing the electrical resistance. Technically, multi-layer layers of metals and alloys that are electrically insulated from one another can already be produced with film thicknesses of 1 mm to 0.025 mm. A further improvement can be achieved by metal / metal oxide powder in a dielectric. The particle sizes are in the range of 2 to 10 µm. Fe, Cu, Mn, Zn and Ni are particularly suitable as metals. The metals are also used as oxides with iron oxide. The general formula for these ferrites is

MO.Fe ₂ O ₃ ,

where M is any metal from the group Fe, Cu, Mn, Zn and denotes Ni. The disadvantage is the high sensitivity to breakage of these ceramic materials.

The disadvantage of ceramic materials is invented Intended use of amorphous metal (metallic Glasses) overcome without accepting other restrictions have to.

Amorphous metals are characterized in that the atoms in are frozen in a largely disordered state. While usually the atoms when cooling from a melt have enough time to form crystal nuclei and Align with these crystal nuclei amorphous metals through rapid cooling of the melt, for example with a cooling rate of one million degrees per second.

Amorphous metals are characterized by several cheap properties from. They are hard, corrosion-resistant, have one high electrical resistance and behave magnetically soft, that is, they have - as already explained above - only a very small hysteresis. This is the loss performance low. Little heat loss is generated and it practically no eddy currents occur.

This small hysteresis and the high electrical resistance as induction-enhancing materials high frequencies.  

The mechanical properties (hardness, resistance to breakage) are very advantageous for building a chip card.

Rapidly solidified cobalt alloys show a lot favorable magnetic, electrical and mechanical properties on and are as tapes with widths up to 20 mm with a thickness of 50 µm can be produced.

According to the external dimensions of a chip card and under Consideration of the mostly very flat, relatively extensive Antenna elements, it is advantageous to increase induction Form element foil or plate-shaped.

It can also be advantageous to increase induction Form element as a multilayer body. The multi-layer body per consists of several plane-parallel layers of the same chem or different material built. By the The thickness of the induction stone can be built up in layers Enlarging element enlarge. The electrical can also Increase resistance perpendicular to the layer planes. Dar in addition, the mechanical rigidity is further reduced improves. By varying different materials can be the magnetic, electrical and / or mechanical Behavior through selection of materials and layer thicknesses put.

In an advantageous embodiment, the layers exist each made of amorphous metal foils.

In a special embodiment, the chip card has one Module carrier on the for direct or indirect Befe Stigung the integrated circuit and preferably also serves to attach the antenna element. Depending on the structure and Manufacturing processes can be divided into two variants the. In the first variant, the chip card comprises a card carrier into which a recess is incorporated, for example is milled. In this variant, the module carrier becomes too  together with the attached components (integrated Circuit, etc.) inserted into the recess. In the second Variant, the module carrier practically forms the card carrier. After fastening the components (integrated circuit, etc.) they are cast on the module carrier, laminated or otherwise to form a Encapsulated chip card.

In a first alternative installation position of the induction element is the integrated circuit on one arranged first flat side of the module carrier, however the induction-increasing element is on the opposite overlying flat side of the preferably plate-shaped Module carrier. The induction increasing element can with the Module carrier can be glued, for example. The plate thickness of the module carrier can be reduced because the induction increasing element makes a significant contribution to mechanical Stiffness of the overall arrangement provides.

The induk is in an alternative installation position tion-enhancing element between the integrated circuit on the one hand and the module carrier on the other. Here too a connection between module carrier and induction increasing Element can be created for example by gluing. By the inherent rigidity of the induction-increasing element the thickness of the module carrier is also reduced here.

In another alternative installation position, the The module carrier is dispensed with and this is due to the induction coil replacing element. The induction increasing element is namely, especially if it is designed as a multilayer board, even sufficiently mechanically stiff. With this alternative Installation position can simplify the manufacture. At Use of amorphous metals as induction increasing Element can also have the desired mechanical properties achievements easily.  

Basically, the antenna element can be relative to the induction increasing element and for the integrated circuit almost be be arranged lovingly. However, the antenna element is preferred ment, especially an etched coil, essentially concentrate around the integrated circuit on which the inte the flat side of the module carrier facing the circuit or the induction-increasing element by an etching process gear trained. Alternatively, the antenna element, especially coil also as a discrete wire coil or as ge punched or printed coil be formed. With a ge printed coil are polymer coil and printed galvanized Distinguish coil. A polymer coil can also be in Form a "dispensed polymer coil".

For connecting the integrated circuit to the antenna element, especially the coil, offer a variety of Connection techniques. First, the integrated circuit circle as a plastic flip chip, as a solder flip chip, as a chip-on Board (wire bond) or as a backbonded chip on the module carrier or the induction-increasing element can be arranged.

If a polymer flip chip is present, this is generally the case Lich an electrically conductive adhesive connection. Especially with Connection to a discrete wire coil can also be the di direct introduction and contact using thermocompression Bonding or thermosonic bonding may be useful.

The integrated circuit is in the form of a solder flip chip before, an electrically conductive connection by soldering, to the antenna or to an intermediate carrier. It should both on the solder flip chip and on that A certain soldering deposit was previously applied to the antenna element become. Alternatively, a welded connection can also be used be formed.  

With the chip-on-board alternative, an electrical con tacting by wire, tapes, metallized foil or a metallized stamped part.

If the integrated circuit is used as a backbonded chip on the Module carrier or the induction-increasing element arranged and if it has discrete wire connections, these can be used with the antenna element by electrically isotropic or anisotropic pes conductive adhesive, by electrically conductive soldering or connected by bonding.

The magnetic flux density can be determined by means of the invention increase and thus the signal transmission between the card and an external read / write station. Furthermore the previously necessary module carrier can be made thinner or be dispensed with entirely. The induction stone the mechanical element Take over the function of the module carrier in whole or in part. As Amorphous metal is also particularly suitable here.

The invention is also described below with respect to others Features and advantages based on the description of execution examples and with reference to the accompanying drawings gene explained in more detail.

Show here:

Figure 1a schematically shows a first alternative mounting position for an induction-enhancing element.

FIG. 1b and 1c different connecting techniques for enhancing induction 1a positioned Ele ment according to Fig.

Figure 2a schematically shows a second, alternative mounting position for an induction increasing element.

Fig. 2b and 2c different connection techniques for an induction-increasing element positioned according to Fig. 2a;

3a shows schematically a third, alternative mounting position for an induction-enhancing element.

FIG. 3b and 3c different connecting techniques for enhancing induction 3a positioned Ele ment according to Fig.

Fig. 4a schematically shows a fourth, alternative installation position for an induction-increasing element and

FIG. 4b and 4c different connection techniques. 4a positioned induction-increasing ele ment for a according to Fig.

In the following description, the same and equivalent components used the same reference numerals. On At this point it is further pointed out that the in the proportions shown in the drawings not the correspond to actual circumstances, but the drawing gene are to be regarded as schematic representations.

A first alternative for the installation position of an induction-increasing element 14 in a chip card is shown purely schematically in FIG. 1a. The different installation positions shown in FIGS . 1a, 2a, 3a and 4a are initially shown relative to a module carrier 16 .

This module carrier 16 can be used together with an integrated circuit 12 , an antenna element 13 and the induction-increasing element 14 in a preferably pre-milled recess from a card carrier, not shown. The invention and in particular the various construction positions for the induction-increasing element can also be used on a card type in which the module carrier 16 extends essentially over the overall dimension of a chip card. The integrated circuit 12 and possibly the antenna element 13 are then encapsulated in a manner known per se. For example, a further card carrier can be laminated onto the module carrier 16 which extends essentially over the entire card, the integrated circuit 12 being embedded between the module carrier 16 and the further card carrier.

The following considerations and explanations are therefore applicable both to the card type in which a recess is provided and to the card type in which the module carrier 16 extends essentially over the entire chip card.

In the first installation variant, the induction-increasing element 14 is arranged on a first flat side 17 of a module carrier 16 . The module carrier 16 can be connected in a suitable manner to the induction-increasing element, for example glued.

On the flat side 18 of the module carrier facing away from the induction-increasing element 14 , an integrated circuit 12 is arranged. An antenna element 13 , in particular a spiral coil, is also formed on this flat side 18 .

The antenna element 13 , in particular the spiral coil, can be designed as a printed coil, namely as a printed polymer coil or as a printed and galvanized coil, as a discrete wire coil, as an etched coil, as a paste coil described or as a punched coil.

In Fig. 1b, a connection variant of the integrated circuit 12 to the antenna element 13 is shown. The inte grated circuit 12 is connected here by electrically conductive adhesive connections 19 to the antenna element 13 . This can be an anisotropic, isotropic or narrow-gap electrically conductive adhesive connections 19 . Instead of the adhesive connections, an intermetallic solder or weld connection can also be considered.

The adhesive, solder or weld connection, in the first Li never constitutes an electrical connection to the antenna element 13. At the same time, however, a mechanical connection is also formed. Since the spiral coil 13 is generally fixed on the module carrier 16 , this adhesive, solder and weld connection creates a mechanical connection to the module carrier 16 at the same time. Module carrier 16 , induction-increasing element 14 , spiral coil or antenna element 13 and integrated circuit 12 thus constitute a unit. Depending on the type of card, this unit can now be inserted into a recess in the card carrier or already form a flat side of the later chip card. Of course, a protective and / or lacquer layer (not shown) can also be applied to the film-like or plate-like element 14 which increases production.

In Fig. 1c further alternative connection variants for the integrated circuit 12 to the antenna element 13 are shown schematically. The integrated circuit 12 can be arranged on the module carrier 16 here, as shown in FIG. 1a. However, it can also be integrated in the module carrier 16 .

In general, a distinction can be made between "chip-on-board" solutions and "chip-in-planted-in-board" solutions. The integrated circuit 12 has connections 24 which are electrically connected to the antenna element or the spiral coil 13 by suitable conductors, in particular bond connections 20 . The bond connections can be formed in a known manner by thermosonic bonding or thermocompression bonding.

The integrated circuit 12 (cf. FIG. 1c) is expediently arranged such that the connections 24 are located on its side facing away from the module carrier 16 . In this order, the bond connections 20 can be produced in a simple and cost-effective manner.

Of course, the integrated circuit 12 and the spiral coil 13 can also be connected in another way by conductors, for example by soldering or welding.

A second alternative installation position for the induction-increasing element 14 is shown schematically in FIG. 2a. Here, too, the induction-increasing element 14 is essentially film-like or plate-like. Unlike in Fig. 1a, it is here arranged between the module carrier 16 and the inte grated circuit 12 . The spiral coil 13 is therefore located directly on the induction-increasing element 14 , specifically on its flat side 23 facing away from the module carrier 16 . Here, too, the spiral coil 13 can be embodied in the alternative embodiments already explained with reference to FIG. 1 a and attached to the induction-increasing element 14 .

In Fig. 2b, the electrical connection of the integrated circuit 12 to the spiral coil 13 by adhesive bonds 19 is shown. Again, instead of glue connections, solder or weld connections for connecting the integrated circuit 12 to the spiral coil 13 can be formed.

Referring to FIG. 2c, the integrated circuit with the spiral coil 13 - as already with reference to Figure 1c be written -. By means of conductors, in particular bond connections 20 are connected.

Fig. 3a shows a particularly advantageous variant for the arrangement of the induction increasing element 14. In this variant, the module carrier 16 is completely dispensed with. In the variants described with reference to FIGS . 1a and 2a, the module carrier 16 was already reinforced by the plate-shaped or foil-shaped induction-increasing element. In the variant shown here, the induction-increasing element 14 is designed to be mechanically rigid in such a way that it completely replaces the module carrier 16 . The induction-increasing element can be of single-layer design here ( FIG. 3a) or also multi-layer construction (see FIG. 3b). In Fig. 3b, 22, the induction increasing element 14 layers 21, which are bonded together into a multilayer body 15 or laminated.

The connection variants ( Fig. 3b and Fig. 3c) correspond to the connection variants already discussed with reference to Fig. 1b, 1c, 2b and 2c.

The induction-increasing element 14 can also be present as a bound powder and can be applied to the module carrier 16 according to FIG. 1a on a first flat side 17 or according to FIG. 2a on a second flat side 18 . Alternatively, the induction-increasing element, if it is present as a bound powder, can also partially or completely surround the spiral coil 13 . In the variant shown in FIG. 4 a , the spiral coil 13 is arranged on the flat side 18 of the module carrier 16 facing the integrated circuit 12 . On this flat side 18 , the induction-increasing element 14 is also applied in the form of bound powder, so that it penetrates the spaces between the individual turns of the spiral coil and encapsulates the spiral coil 13 as a whole.

The encapsulation of the spiral coil 13 shown here by the induction-increasing element 14 in the form of bundled powder can also be combined with the previously described variants according to FIGS . 1a, 2a or 3a to further increase the induction.

The connection variants already discussed with reference to FIGS . 1b, 2b, 3b and 1c, 2c, 3c are shown schematically in FIGS . 4b and 4c. If the induction-enhancing element 14 is in the form of bound powder, the connections, in particular the adhesive connections 19 or the conductor 20 and parts of the integrated circuit 12 , can also be embedded by the bound powder forming the induction-enhancing element.

The arrangements described for the induction-increasing element 14 can - as already mentioned - be combined with each other. However, other arrangements are also conceivable, with positioning of the induction-increasing element above, below or within the spiral coil being preferred.

The induction-increasing element 14 is formed from amorphous metal. The amorphous metals are magnetically soft and are characterized by a very low hysteresis, which enables use even at high frequencies. In addition, they have a very high specific resistance, so that no significant eddy currents can form. Amorphous metals based on Co alloys are particularly preferably used. They can be easily manufactured as tapes with widths up to 20 mm and a thickness of 15 µm and inserted into a chip card. In this case, the induction-increasing element 14 can also be produced from a plurality of belts arranged side by side and one above the other.

If a chip card with an induction-increasing element is provided, are less strong Er for signal transmission excitation currents required. Due to the increased magnetic flux density can the signals in the transmit and receive mode of the Reinforce chip card.

The installation options for an induk described above tion-enhancing element, especially made of amorphous metal are purely exemplary. It can also be turned on different installation positions and geometries for the induction coil training element form without ver ver the scope of the invention to let.

Reference list

12th

integrated circuit

13

Antenna element, spiral coil

14

induction increasing element

15

Multilayer body

16

Module carrier

17th

one flat side (module carrier)

18th

other flat side (module carrier)

19th

Adhesive connection

20th

Conductors, bond connections

21

,

22

layers

23

Flat side (induction increasing element)

24th

Connections

Claims (11)

1. Chip card with an integrated circuit ( 12 ) and an antenna ( 13 ) implemented in the card body for contactless transmission of data, characterized in that the antenna ( 13 ) cooperates with an induction-increasing element ( 14 ) with a relative permeability µ _r <1 , wherein the element ( 14 ) consists at least partially of amorphous metal (metallic glass). 2. Chip card according to claim 1, characterized, that the amorphous metal grain sizes <10 microns and a high has electrical resistance.   3. Chip card according to claim 1 or 2, characterized, that the amorphous metal solidified quickly Cobalt alloy is formed. 4. Chip card according to one of claims 1 to 3, characterized in that the element ( 14 ) is plate-shaped or foil-shaped. 5. Chip card according to one of claims 1 to 4, characterized in that the element ( 14 ) consists of several plane-parallel layers ( 21 , 22 ) and is designed as a multilayer film or multilayer body ( 15 ). 6. Chip card according to claim 5, characterized in that the multilayer body ( 15 ) consists of several interconnected, in particular glued amorphous metal foils. 7. Chip card according to claim 6, characterized, that the film thickness of the metal foils in the area between 1 mm and 0.025 mm. 8. Chip card according to one of claims 1 to 7, characterized in that the chip card further comprises a module carrier ( 16 ), wherein the module carrier ( 16 ) on a flat side ( 17 ) with the induction-increasing element ( 14 ) is provided and on the opposite flat side ( 18 ) of the module carrier ( 16 ) the integrated circuit ( 12 ) is arranged. 9. Chip card according to claim 8, characterized in that the antenna ( 13 ) on the integrated circuit ( 12 ) facing flat side ( 18 ) of the module carrier ( 16 ), preferably arranged substantially concentrically around the integrated circuit ( 12 ). 10. Chip card according to one of claims 1 to 7, characterized in that the chip card further comprises a module carrier ( 16 ), wherein the induction-increasing element ( 14 ) between the integrated circuit ( 12 ) and module carrier ( 16 ) is arranged and the integrated Circuit ( 12 ) on the induction-increasing element ( 14 ) on the module carrier ( 16 ) is attached. 11. Chip card according to one of claims 1 to 7, characterized in that the induction-increasing element ( 14 ) is designed as a module carrier ( 16 ) and the integrated circuit ( 12 ) can be fastened directly to the induction-increasing element ( 14 ).