DE19962194A1 - Production of conductor loops for transponders comprises forming conductor loop on one side of deformable substrate, lengthening loop and folding substrate between lengthened outer end and outer end of loop - Google Patents

Abstract

Production of conductor loops for transponders comprises forming a conductor loop (7) with at least one winding on one side of a deformable substrate (8) in such a way that the loop initially has an inner (10) and an outer end (16); lengthening the loop originating from the outer end around a piece that is directed outwards; and folding the substrate between the lengthened outer end and the outer end of the loop so that the lengthened outer end lies over the region of the substrate which is defined by the inside of the loop. An Independent claim is also included for the production of transponders comprising forming the above conductor loop; insulating the crossing loop windings; applying chips to the substrate; and connecting the joining surfaces of the chip with the inner and the lengthened outer ends of the loop. Preferred Features: The conductor loop is made of indium-tin oxide.

Description

The present invention relates to a method for producing con tactile conductor loops for transponders according to the preamble of the patent claim 1, as well as a method for producing transponders according to Preamble of claim 18.

Many areas of public life have been strengthened in recent years RFID systems used to identify any objects. The term RFID stands for radio frequency identification and denotes an identification by means of radio waves.

An RFID system always consists of two components: an evaluation device, the can be designed as a reading and / or writing unit, and a transponder, which carries the data used for identification.

The most widespread application of transponders are contactless chips cards that are now mostly used as payment in the form of credit cards, or as an access control device in the form of access tickets or company ID cards be used. Contactless chip cards allow easy handling, are designed to be robust and thus have a low susceptibility to interference, and offer a number of interesting possibilities in use.

The contactless chip cards currently manufactured contain on a substrate that usually has the size of a check card, a small-area chip and a coupling element. The coupling element is either used as a dipole capacitive coupling, or as a conductor loop for a predominantly inductive Coupling trained. While the capacitive coupling is usually only for short distances of the contactless chip card from an evaluation device is suitable because otherwise high voltages would be required with realistic coupling capacities ren, the inductive coupling offers the advantage of being operated in resonance can. For this purpose, the conductor loop with a capacitance becomes an oscillating circuit connected, which is matched to the working frequency of the contactless chip card.  

Furthermore, when using contactless chip cards, the energy required to operate the chip card via the coupling element without contact Chip card transmitted so that the contactless chip card does not have its own Must have a voltage source and in particular outside the area of operation of an evaluation device behaves completely passively.

In the currently used contactless chip cards with inductive coupling, at which a conductor loop takes over the function of the coupling element is a Ver chip or a chip module via appropriate contacts with the conductor loop bound to be able to communicate with the outside world. To achieve the water electrical connection between the conductor loop and the chip or chip module several procedures have already been proposed.

FIG. 3 shows a substrate 8 , which has the size of a check card, for example, with a conductor loop 7 . A chip module 1 , comprising a chip 5 with connection surfaces 6 , is electrically conductively connected via external contacts 2 of the chip module 1 to contact connections 3 of the conductor loop 7 , the external contacts 2 being connected via contact elements 4 to the connection surfaces 6 of the chip 5 . As is illustrated in FIG. 3, a “bare” chip 5 can be connected to the conductor loop 7 instead of the chip module 1 .

Here, one or more turns of the conductor loop 7 are crossed in order to connect the chip module 1 or the bare chip 5 to an inner and an outer end of the conductor loop 7 . When using the chip module 1, the crossing over one or more turns is carried by the housing of the module 1, which causes insulation of the crossed coils. In another variant, the bare chip 5 itself can be glued to the turns to be crossed.

While the manufacture of a chip module 1 is time-consuming and expensive, a bare chip 5 must be encapsulated to protect against mechanical, electrical or thermal influences after establishing an electrical connection to a conductor loop 7, as a rule by means of a sealing compound.

FIG. 4 shows a further possibility for crossing one or more windings of a conductor loop 7 on a substrate 8 according to the prior art. An inner end 10 of the conductor loop 7 is connected to a first contact connection 3 , which lies in the area defined by the innermost turn. The far ren an outer end 16 of the conductor loop 7 is connected via a connecting element 9 to a second contact terminal 3 , which is also in the range defined by the first turn, so that a chip module 1 via external contacts 2 with the contact terminals 3 is electrically conductive can be connected. Instead of the chip module 1 , a bare chip 5 , as shown in FIG. 4, can also be connected to the conductor loop 7 via contact elements 4 . Furthermore, a bare chip 5 can be brought up to the substrate 8 by means of a flip-chip process in such a way that its connection surfaces 6 lie opposite the contact connections 3 .

The connecting element 9 is either formed on the surface of the substrate 8 , on which the conductor loop 7 is located, or on the opposite surface. These two possibilities are explained in more detail in FIGS. 5 and 6.

Fig. 5 illustrates the principle of how the turns to be crossed of the conductor loops fe 7 are isolated to avoid short circuits, for example by means of a lacquer 19 or by anodizing. Thus, the connecting element 9 can be formed by crossing the windings insulated in this way on the surface of the substrate 8 on which the conductor loop 7 is located. For example, a silver conductive adhesive is used as the connecting element 9 .

A major disadvantage here is that the connecting element 9 must be designed very precisely in order to avoid a possible short circuit in adjacent areas.

Fig. 6 illustrates the principle of a via, wherein the Verbindungsele element 9 is formed on the surface of the substrate 8 , which is opposite to the surface on which the conductor loop 7 is located. In order to establish an electrical connection between the outer end 16 and the second contact connection 3 and the connecting element 9 , the substrate 8 must be contacted by. According to the prior art, this is done, for example, by means of etching.

A major disadvantage here arises from the need to form the connec tion element 9 on the "back" of the substrate 8 , which results in long process times and additional costs. Furthermore, the through-contacting represents an additional uncertainty in the manufacturing process due to a high requirement for the accuracy of the work step.

Based on the known state of the art and the above disadvantages is the object of the present invention to create a possibility easy, quick and inexpensive contactable conductor loops for transpon the manufacture, in particular a protection ankon to the conductor loop clocked chips before chemical, electrical, mechanical and thermal input rivers to be provided.

This object is solved by the subject matter of claims 1 and 18. Preferred embodiments of the invention are the subject of the dependent claims.

According to a particular aspect of the present invention, conductor loops fen designed for transponders on substrates that are application-specific Pieces are extended, which is explained in more detail below. Can as a substrate for example organic polymers, paper, fabric and especially Mi can be used from these materials. In the event that the Trans ponder should be used as a contactless chip card, points out the corresponding Substrate preferably the dimensions of a common check card. The Conductor loops each include one or more turns and are pre- preferably starting from an inner end, for example along the sides  of the substrate is formed toward an outer end. The conductor loop is thus preserved fe preferably a rectangular shape, but it can also be in another geometric shape, depending on the configuration of the invention ß transponders are trained.

If the conductor loop comprises two or more turns, it is preferred extending from its outer end by a piece that is at least the Has the length of the distance between the outermost and innermost turns and be is directed towards the inside of the conductor loop, whereby a new, elongated outer end is formed. In the event that the conductor loop only a turn comprises the extension by a piece that is at least the Has length of the distance between the outer end and inner end.

According to a particular embodiment of the present invention, the Substrate in a further step along a line that is preferably between the elongated outer end and the outer end is folded such that the elongated outer end after folding over the area of the substrate lies, which is defined by the inside of the conductor loop. Thus the Windun only crossed by the elongated piece towards the conductor loop. Furthermore the line along which the substrate is folded can be a pre-made edge, perforated, scored or embossed to fold facilitate.

According to a further special aspect of the present invention, the Li never, at which the substrate is folded, in the middle of the substrate, so that after the Folding creates a folded substrate of uniform thickness. Should the folded Substrate have the dimensions of a common check card, so points the substrate to be folded is preferably twice the length of a check card. In other variants, the substrate can be folded such that, for example, only the area that is defined by the conductor loop or the area to which a Chip is applied, is enclosed by the folded substrate.  

According to a further particular aspect of the present invention, the Folded substrate so that the inner end and the extended outer end of the conductor loop face each other, so that a Chip, the two surfaces of which are formed as pads, immediately can be contacted. A major advantage of such contacting is that the chip before folding without complicated adjustment procedures on the inner end of the conductor loop can be applied and that in the contact tion with the extended outer end due to the high accuracy of the Wrinkles in turn a complicated adjustment procedure is avoided.

When using current chips, their pads are on have an "active" side, in the area defined by the interior of the Lei is defined, such a dimensioned contact surface is applied, that both the pad to be contacted and the extension te outer end of the conductor loop after folding with this contact surface tric conductive can be connected. Furthermore, chip Contact element units are used, each one chip and minimum least have a contact element, the contact elements with the inner End and the extended outer end are electrically connected.

The main advantages of the present invention are that only a surface of the substrate is worked so that vias ver be avoided. In particular, a highly accurate method for manufacturing Contactable conductor loops are provided for transponders, which enables on simple and fast way to provide contactable conductor loops. Furthermore, by folding a substrate, the chip can be encapsulated and / or the conductor loop of the transponder, thereby protecting against chemical, electrical, mechanical and thermal influences.

The proposed method can be used in the production of contactless chip cards be applied. Furthermore, according to a preferred embodiment in the manufacture of transponders, for example as security labels Find use on a transparent substrate also a transparent  Conductor loop made of a conductive, transparent material, for example made of In dium tin oxide (ITO). This creates a transponder which, with the exception of the chips used, is quasi transparent. Such trans When used as security labels, ponders allow, for example, that after the sale of an object to be secured, the security is removed label becomes superfluous. In the event that the conductor loop remains visible to ensure the presence of a security label on the to be secured To illustrate the object, the conductor loop can only partially be made of egg, for example a conductive, transparent material, for example made of indium tin oxide (ITO), be formed.

According to a further preferred embodiment, card-shaped transpos can who are produced, for example in the form of a sticker application fin the.

In particular, the substrate of a transponder according to the invention can be preferred be filled with ferrite to function advantageously in a metal environment.

Preferred embodiments of the present invention are as follows explained in more detail with reference to the accompanying drawings. Show the drawings in detail:

Figure 1a is a schematic view of a conductor loop with extended outer end on a substrate.

Fig. 1b is a schematic side view illustrating a folding of the conductor loop substrate according to Fig. 1a;

FIG. 1c is a schematic side view of a folded conductor loop substrate according to Figures 1a and 1b.

FIG. 2 shows schematic side views of folded conductor loop substrates according to FIG. 1c with chips connected;

FIGS. 3 and 4 are schematic views of conductor loops having ankontaktierten chip modules or chips on a substrate according to the prior art; and

Fig. 5 and 6 are schematic side views of conductor loops having ankontaktierten chip modules or chips on a substrate according to the prior art.

Figs. 1a to 1c illustrate by way of example, the inventive method for the manufacture of position contactable conductor loops for transponders. 1 a shows a deformable substrate 8 with a conductor loop 7 , which has an inner end 10 and an outer end 16 , the inner end 10 being inside and the outer end 16 outside the conductor loop 7 , and an elongated outer end 11 . In the present example, the conductor loop has two turns for the sake of clarity in the representation of the method according to the invention.

In a first step, the conductor loop 7 is formed on the substrate 8 . This can be done by continuously "winding" the turns from one of the two ends 10 , 16 to the other end 16 , 10 . Here, as indicated in FIG. 1 a, the conductor loop 7 along the sides of the substrate 8 can preferably be formed in a rectangular shape. However, it can also have other geometric shapes depending on the design of the transponder according to the invention.

The conductor loop 7 is extended in a further step starting from the outer end 16 by a piece 12 which has at least the length of the distance between the outermost and innermost turn and is directed outwards with respect to the conductor loop 7 . In the example shown, the conductor loop 7 has been extended from point 16 by a piece 12 , so that a new, extended outer end 11 is formed.

At the extended outer end 11 and the inner end 10 contact terminals 3 are formed for the sake of clarity of illustration.

As shown in Fig. 1a, the substrate 8 can be divided along a line 13 into two under different parts of lengths 17 and 18 . The part of length 17 includes conductor loop 7 with inner end 10 and outer end 16 . The extended outer end 11 lies in the part of the length 18 . Line 13 preferably lies between the elongated outer end 11 and the outer end 16 , the substrate 8 being folded along this line such that the elongated outer end 11, after being folded, lies over the area of the substrate 8 which passes through the interior of the Conductor loop 7 is defined. The turns of the conductor loop 7 are only crossed by the extended piece of length 12 . Furthermore, the line 13 can be a prefabricated edge which has been perforated, scored or embossed, for example, in order to thus facilitate folding.

Furthermore, in Fig. 1a with the reference characters Ib and Ic lines are marked, along which cuts for the creation of the schematic side views according to FIGS . 1b and 1c were carried out, the attached arrows representing the respective viewing direction.

Fig illustrated. 1b as the substrate 8 is folded along the line 13 in the direction of arrow 14, wherein the crossed conductor loop windings are isolated, for example by an appropriate anodizing or coating a lacquer. In this way, short circuits between the crossed conductor loop turns and the lengthened piece of length 12 are to be avoided.

Fig. 1c shows a according to Fig. 1b pleated substrate 8 with a conductor loop 7, wherein inner end 10 and outer end 11 are each constructed as contact terminals 3.

As Figs. 1a to 1c show, there is a significant advantage of the present OF INVENTION manure that is carried out for producing a contactable conductor loop 7 exclusively on one side of the substrate 8. This eliminates the through-plating that is customary in the prior art.

Furthermore, the substrate 8 can preferably be filled with ferrite in order to function advantageously in a metal environment.

According to a preferred embodiment of the present invention, an encapsulation, for example a chip (not shown) or the conductor loop 7 , can be sufficient, which contributes to the protection of these elements from chemical, electrical, mechanical and thermal influences. There are several possibilities for this with regard to the total length of the substrate 8 . In a preferred embodiment, the length 17 can correspond to the length 18 , so that the substrate 8 is folded in the middle and thus has a uniform thickness after folding. Furthermore, the conductor loop 7 can be designed such that it does not occupy the entire area of the part of the length 17 , so that the length 18 can be selected such that only the complete conductor loop 7 is covered after folding. According to a further embodiment, the length 18 can also be selected in such a way that after folding the substrate 8 only a region of the conductor loop 7 is covered, onto which a chip to be contacted (not shown) is applied.

The above-described method of folding substrates 8 with conductor loops 7 for transponders can, according to a preferred embodiment of the present invention, also be used to produce contactable conductor loops 7 for contactless chip cards. Here, the size of the part of the length 17 of the substrate 8 preferably has the size of the card body of a customary contactless chip card, which is extended by a certain length 18 in accordance with the requirements of the respective application.

In Fig. 2 three possibilities c1 to c3 are indicated, which illustrate how a chip 5 , having connection pads 6 , with contact connections 3 from the inner end 10 and extended outer end 11 of a conductor loop (not shown) on a substrate folded according to Fig. 1c 8 can be electrically connected.

Fig. 2 (c1) illustrates how a contact surface 15 is applied to the substrate 8 inside the conductor loop (not shown) and the substrate 8 is folded such that the elongated outer end 11 rests on part of the contact surface 15 . In this case, the extended outer end 11 can be connected to this contact surface 15 , for example by means of gluing, soldering or welding.

In a further step, the chip 5 can be applied with its active side to the substrate 8 in such a way that the connection surfaces 6 with the contact surface 15 and the contact connection 3 of the inner end 10 lie opposite one another and can be connected to them in an electrically conductive manner.

Figure 2 (c2) illustrates a folded substrate 8 in which the elongated outer end 11 and the inner end 10 overlap after being folded. The chip 5 , the sen both surfaces are formed as pads 6 , can be brought in a further step between the contact terminals 3 of the elongated outer end 11 and the inner end 10 , wherein an electrical connection is made with the conductor loop, not shown.

A major advantage of this possibility lies in the size of the connection areas 6 of the chip 5 , which offer suitable light protection for the chip 5 . Furthermore, complex adjustment procedures are avoided by the principally highly precise folding process.

Fig. 2 (c3) illustrates how a chip contact element unit consisting of a chip 5 with pads 6 and attached contact elements 4 can be used. Here, the contact elements 4 are electrically conductively connected to the contact connections 3 of the elongated outer end 11 and the inner end 10 of the conductor loop, not shown. In a preferred embodiment of the present invention, the contact connections 3 are formed such that they have at least a height which corresponds to the height of the chip 5 with the connection surfaces 6 . Thus, an electrical connection between the contact elements 4 and the contact connections 3 can already be made by pressing the folded substrate 8 together .

Claims (18)

1. A method for producing contactable conductor loops for transponders, characterized by the following steps:
Forming a conductor loop with at least one turn on one side of a deformable substrate such that the conductor loop first has an inner and an outer end, the inner end being inside and the outer end being outside the conductor loop;
Extending the conductor loop starting from the outer end by a predetermined length which is directed outwards with respect to the conductor loop; and
Folding the substrate between the elongated outer end and the outer end of the conductor loop such that the elongated outer end after folding lies over the area of the substrate that is defined by the inside of the conductor loop. 2. The method according to claim 1, characterized in that the conductor loop two or more turns includes that the predetermined piece is at least the Length of the distance between an outermost and an innermost turn and the conductor loop turns after folding only extend from that be crossed. 3. The method according to claim 1 or 2, characterized in that the windun be circular. 4. The method according to claim 1 or 2, characterized in that the windun gene in a rectangular shape along the sides of the substrate.   5. The method according to any one of claims 1 to 4, characterized in that the substrate is folded in the middle and thus a uniform after folding che thickness. 6. The method according to any one of claims 1 to 4, characterized in that the substrate is folded in such a way that the complete conductor loop after folding fe is covered. 7. The method according to any one of claims 1 to 4, characterized in that the substrate is folded such that after folding only a portion of the lei is covered loop on which a chip to be contacted is applied. 8. The method according to any one of claims 1 to 7, characterized in that the elongated outer and inner ends were superimposed after folding gene. 9. The method according to any one of claims 1 to 7, characterized in that on the substrate in the interior of the conductor loop, a contact surface is applied and the elongated outer end after being folded on the contact surface rests that a chip is electrically conductive with the conductor via this contact surface loop can be connected. 10. The method according to any one of claims 1 to 9, characterized in that folding along a pre-made edge. 11. The method according to claim 10, characterized in that the prefabricated Edge is formed by perforating. 12. The method according to claim 10, characterized in that the prefabricated Edge is formed by scratching. 13. The method according to claim 10, characterized in that the prefabricated Edge is formed by embossing.   14. The method according to any one of claims 1 to 13, characterized in that the conductor loop partially or completely made of an optically transparent, elec trically conductive material is formed. 15. The method according to claim 14, characterized in that the used Material is Indium Tin Oxide (ITO, Indium Tin Oxide). 16. The method according to claim 14, characterized in that the used Material is a transparent conductor based on a highly conductive electrolyte. 17. The method according to claim 14, characterized in that the used Material is a transparent conductor based on a highly conductive polymer. 18. A method for producing transponders, characterized in that the following steps are carried out to establish an electrical connection between the pads of the respective chips and the inner and outer ends of the respective conductor loop:

• - Forming a contactable conductor loop with at least one turn on one side of a deformable substrate by extending the conductor loop starting from the outer end and then folding the substrate such that the elongated outer end after folding lies over the area of the substrate that passes through the interior the conductor loop is defined and the conductor loop turns are only crossed by the extended piece.
• - Isolation of the crossed conductor loop turns;
• - Application of the chip on the substrate; and
• - Connecting the pads of the chip with the inner and the elongated outer end of the conductor loop.