WO2003091962A1

WO2003091962A1 - A method for maufacturing a product sensor, and a product sensor

Info

Publication number: WO2003091962A1
Application number: PCT/FI2003/000312
Authority: WO
Inventors: Samuli STRÖMBERG; Marko Hanhikorpi; Mikko Tirkkonen
Original assignee: Upm Rafsec Oy
Priority date: 2002-04-25
Filing date: 2003-04-17
Publication date: 2003-11-06
Also published as: AU2003222859A1; FI20020797A0; FI113570B; FI20020797A

Abstract

The invention relates to a method for manufacturing a product sensor (2), and a product sensor (2). The product sensor (2) is provided with a circuitry pattern to produce an electrical oscillating circuit (L, C1, C2), and at least one fuse (F) for deactivating the electrical oscillating circuit (L, C1, C2). In the method, at least two modules (3, 5) are formed, the first module (3) being provided with at least a coil (L) for an electrical resonance circuit, and the second module (5) being provided with at least the fuse, and said at least two modules (3, 5) are connected to each other.

Description

A METHOD FOR MANUFACTURING A PRODUCT SENSOR, AND A PRODUCT SENSOR

The present invention relates to a method for manufacturing a product sensor, wherein the product sensor is provided with a circuitry pattern to produce an electrical oscillating circuit, and at least one fuse to deactivate the electrical oscillating circuit. The invention also relates to a product sensor which comprises an oscillating circuit formed by a circuitry pattern, and at least one fuse to deactivate said electrical oscil- lating circuit.

In this description, a product sensor refers to an electric coupling which is formed in connection with a product or a product package or on a separate substrate and which can be used for identifying the product, for example as a product protection for preventing thefts (anti-theft sensor), and/or as an identification means for identification of the product/user. Product sensors formed on a separate substrate can be attached to the product preferably by glueing or by sewing, but also other methods can be applied.

Product protection sensors are used in connection with products to prevent possible attempts of stealing the product. Products are thus equipped with a product sensor used as a product protection sensor, and the exits of shops are equipped with detectors by which such a product protection sensor can be detected if it has not been deactivated in the shop. The product protection sensor is deactivated at the stage when the product is duly paid for at a cash desk. As a main rule, such a deactivated product protection sensor is not detected by the detectors, wherein unnecessary alarms are avoided.

These product sensors used as product protection sensors and/or for identification are normally made of a thin plastic film which is coated on both sides by laminating the surface of a plastic film with an aluminium film. A colouring agent is advantageously applied onto the aluminium films by using e.g. the gravure printing technique. The colouring agent is used to produce a desired pattern on the metal film, wherein when the metal is removed e.g. by etching off, a metal pattern is left which forms the desired electric circuit. Such an electric circuit in the product sensor normally consists of a resonance circuit (oscillating circuit) comprising one or more coils and a capacitor. The purpose of the resonance circuit in the product protection sensor is e.g. that the detector can detect the presence of this resonance circuit, if the product protection sensor has not been deactivated. In identification applications, the resonance circuit is used e.g. to transfer electric energy to the product sensor as well as to transmit information between the product sensor and a reading and/or writing device for the product sen- sor.

To detect the product sensor in a sufficiently reliable manner in the reading device, the quality value of the resonance circuit must be very high in present product sensors of standard size, for example 40 mm x 40 mm. Established practice in the field requires a minimum value of 70 for the quality value Q. However, as the aim in the manufacture of the product sensor is to implement the product sensor in a cost-effective way and with a large volume, in practice, a compromise must be made in the electric properties of the coil conductor. In practice, this means that the conductivity of the conductors in products on the market is similar to that of bulk aluminium or even slightly poorer. With this conductivity, product sensors on market typically reach a quality value in the order of 70 to 80.

Deactivation of the product protection sensor can be performed for example by providing the capacitor plates of the product protection sensor with a breakdown which short-circuits the capacitor plates and thereby eliminates the resonance circuit. A problem in such deactivation is for example the fact that the breakdown is not necessarily per- manent, wherein the product sensor can be re-activated for example by bending of the product sensor. Another problem with such product sensors to be deactivated with an electric field is that discharges of static electricity typically occur in automatic packaging and labelling lines, which may cause deactivation of the product sensor already at the stage of packaging or labelling. Also, product sensors are known in which the deactivation is performed by breaking a fuse formed in the resonance circuit. The breaking is implemented in such a way that the product sensor is subjected to an electromagnetic field whose frequency is substantially the resonance frequency, which produces a high current intensity in the resonance circuit. This current passes also through the fuse, and since the fuse is designed to have such a capacity that it will bum off at a certain current intensity, the fuse can normally be broken by means of this electromagnetic field. One problem in such a fuse arrangement is that in prior art manufacturing methods, the production tolerances of the fuse are relatively large, wherein the current intensity required for breaking the fuse is not necessarily within the allowed limits in different single product sensors. In some product sensors of prior art, this fuse is made with a separate conductor which is connected to conductors formed in a serial resonance circuit. This so-called wire ponding method is expensive and has a small production capacity compared with e.g. the above-mentioned product sensors implemented with the etching method, in which the fuse is also made with a corresponding method.

The operation of the fuse is based on the idea that it is heated and burnt off by the effect of the current in the circuit. Because of this operating mechanism of the fuse, the fuse impairs the Q value of the product sensor. Thus, a fuse cannot be added in a typical product sensor of prior art e.g. by pressing with a conductive paste without reducing the Q value below the acceptable level. On the other hand, in product sensors based on breakdown, the deactivating mechanism does not considerably reduce the Q value, because the deactivation is not based on the use of resistive components.

Yet another electrical technical problem related to product sensors lies in the fact that the difference between the magnetic fields which the product sensors should resist and, on the other hand, in which the product sensor should be deactivated, is very small. Typically, the product sensor should resist a magnetic field in the order of 0.9 A/m and, in a corresponding manner, a magnetic field in the order of 1.5 A/m should be sufficient for deactivation. Consequently, in the design of the fuse, this requires precise control of the resisting proper- ties, low resistivity, and balancing of the total resistance of the oscillating circuit between the different components. The requirement of low resistivity is due to the fact that a stronger field must induce a sufficiently higher current intensity that is induced by a weaker field in the circuit.

The manufacture of the product sensor also involves some problems, such as the quantity of material for the fuse. To make the current for inducing a deactivating field sufficient for burning the fuse, the quantity of material in the fuse must be very small compared with for example the quantity of material required for the coil conductor. Furthermore, this quantity of material for the fuse must be very precisely controllable. The smaller the quantity of material used for making the fuse, the smaller its resistance load with respect to the rest of the circuit, and the less the reduction in the Q value caused by the fuse. Furthermore, with more precise controllability of the quantity of material, the current required for burning off the fuse can be predicted better; in other words, the burning of the fuse can be made more reliable. By improving the production tolerance of the fuse, it is possible to slightly increase the manufacturing tolerances of the coil and the capacitor.

Another problem related to the manufacturing technique is the way in which the small quantity of material required in the fuse is placed in the product sensor which is made by machines from one roll to another and on a film in which the dimensional error can easily be in the order of even one percent.

Yet a third problem in the manufacturing techniques relates to the adhesion and contact resistance between two different interfaces. In practice, the only possible materials for the coil conductor are copper and aluminium, because of e.g. the required high Q value. However, copper and aluminium very easily form an inherent oxide layer which unnecessarily increases the resistance value of the fuse without being actually an element to be burnt off.

Yet a fourth problem in the manufacturing technique relates to the mechanical properties of the fuse. As the product sensor is typically flexible and is manufactured from one roll to another, the production material must be flexible. Furthermore, the electrical conductivity properties of this production material must not be significantly changed by the effect of even reasonable bending. Because of the above-men- tioned manufacturing and electrotechnical problems, the product sensor cannot be made by using the etching technique only.

Also, the manufacture of the capacitor causes problems in the manufacture of the product sensors. One reason for this is that the substrate used in the capacitor must be a sheet-like material with good thermal stability. Such materials typically have a dissipation factor in the order of 0.01 or higher.

On the basis of the above-described problems, it is obviously difficult to manufacture a reliable product sensor of sufficiently good quality in a cost-effective manner.

It is an aim of the present invention to provide a method for the manufacture of a product sensor in such a way that the properties of the product sensor can be improved from the product sensors of prior art. Another aim of the invention is to achieve a product sensor with improved properties. The invention is based on the idea of forming the fuse and at least the coil structure of the electrical resonance circuit as separate modules which are connected to each other by means of a thermoplastic film or by another known technique. The module comprising the fuse may also comprise a part of the electrical resonance circuit. To put it more precisely, the method according to the present invention is primarily characterized in forming at least two modules, the first module being provided with at least the coil of the electrical reso- nance circuit and the second module being provided with at least the fuse, and connecting said at least two modules to each other. The product sensor according to the invention is primarily characterized in that the product sensor comprises at least two modules, the first module being provided with at least the coil of the electrical resonance cir- cuit and the second module being provided with at least the fuse, and that said at least two modules are connected to each other. In the method according to an advantageous embodiment of the invention, said at least two modules are connected to each other by means of a thermoplastic film.

Considerable advantages are achieved by the present invention when compared with the manufacturing methods and product sensors of prior art. When applying the method according to the invention, no compromises need to be made between the different functional units of the product sensor, but both the electrical resonance circuit and the fuse can be implemented to have as good properties as possible. Furthermore, by the method according to the invention, easy variability can be achieved in the manufacture of the product sensor, because different modules can be combined to each other to achieve, as the final result, a product sensor which corresponds, as well as possible, to the properties desired at the time. Thanks to the module structure, different substrate materials can be used in the manufacture of the coil and in the manufacture of the fuse. Consequently, the capacitor can be made in connection with the manufacture of the coil, because, for example, polyolefins with a low dissipation factor can be used in the production line to be used for the manufacture of the coil. By the method of the invention, the product sensors can be made relatively fast and at relatively low junction temperatures. Thanks to the low junction temperatures, it is possible to use materials with a lower thermal stability, which may often have, for example, better dielectric properties than materials with a higher thermal stability. In some applications, the modules can be joined together in a contactless manner, wherein junction resistances are avoided. Also when a contact coupling is used, lower joint resistances and good joint reliability are achieved than in prior art.

Moreover, in the manufacture of the capacitor, there is no need to use a two-layer structure, because the different plates of the capacitor can, if necessary, be implemented by forming one plate in the first module and the other plate in the second module. When the modules are combined, the plates of the capacitor are substantially aligned with each other in the different modules, wherein the capacitor is functional. In this way, the capacitor to be formed can be provided with an even junction capacitance. When applying the method according to the invention, a variety of manufacturing techniques, such as additive methods, can be used in the manufacture of the coil. It is also possible to use subtractive tech- niques, i.e. etching techniques.

In the manufacture of the product sensor according to the invention, it is also possible to use various fuse manufacturing techniques, including the use of selective resists, pattern vaporization, printing with con- ductive pastes, the use of resists exposed on a film and/or the use of a separate component fuse.

In the method according to an advantageous embodiment of the invention, the required junction tolerances are not as strict as in the methods of prior art, wherein the yield becomes better.

In the manufacture of the product sensor according to the invention, it is possible to use dielectrics which can be printed, laminated and/or coated (e.g. extrusion coating).

The method of the invention can be automated easily and at low costs. Yet another advantage of the method according to the invention is that the extra material costs are relatively low.

In the following, the invention will be described in more detail with reference to the appended drawings, in which

Fig. 1a shows the first module of a product sensor according to an advantageous embodiment of the invention, seen in a top view,

Fig. 1b shows the second module of a product sensor according to an advantageous embodiment of the invention, seen in a top view,

Fig. 2 shows a product sensor composed of modules according to Figs. 1a and 1b, in a reduced cross-section at A-A, Fig. 3a shows the first module of a product sensor according to another advantageous embodiment of the invention, seen in a top view,

Fig. 3b shows the second module of a product sensor according to another advantageous embodiment of the invention, seen in a top view,

Fig. 3c shows a product sensor composed of modules according to Figs. 3a and 3b, in a reduced cross-section at B-B,

Figs. 4a to 4f show different steps of the method according to an advantageous embodiment of the invention in a reduced cross-section at A-A of Fig . 1b,

Fig. 5 shows the electric equivalent coupling in a product sensor according to an advantageous embodiment of the invention,

Fig. 6 shows the step of combining the modules in the method according to an advantageous embodiment of the invention,

Fig. 7a shows the first module of a product sensor according to yet another advantageous embodiment of the invention, seen in a top view,

Fig. 7b shows the second module of a product sensor according to yet another advantageous embodiment of the invention, seen in a top view,

Fig. 7c shows a product sensor composed of modules according to Figs. 7a and 7b, in a reduced cross-section at E-E,

Fig. 8a shows the first module of a product sensor according to yet another advantageous embodiment of the invention, seen in a top view, Fig. 8b shows the second module of a product sensor according to yet another advantageous embodiment of the invention, seen in a top view, and

Fig. 8c shows a product sensor composed of modules according to Figs. 7a and 7b in a reduced cross-section at G-G.

The following is a description on the method according to an advantageous embodiment of the invention, wherein the first module 3 of a product sensor 2 according to the invention is manufactured on a first substrate 1, such as a label laminate. Figure 1a shows the first module 3 of the product sensor 2 according to an advantageous embodiment of the invention, seen in a top view. In a corresponding manner, the second module 5 of the product sensor 2 according to the invention is made on a second substrate 4. Figure 1b shows the second module 5 of the product sensor 2 according to one embodiment of the invention, seen in a top view. In this context, it should be mentioned that, for the sake of clarity, the appended Figs. 1 to 8 do not necessarily have correct dimensions. The substrate materials to be used in the first 3 and the second module 5 are preferably flexible, wherein the finished product sensors 2 can be, for example, wound on a roll and they can be used in connection with a large variety of products. Examples of such substrate materials to be mentioned include polyethylene terephtalate (PET) and polypropylene (PP).

Although in the following description, the manufacturing method of the invention will be described primarily in view of the manufacture of a single product sensor 2, it is obvious that the method of the invention can be used to manufacture several product sensors 2 simultaneously. Also, it is obvious that the manufacture of the modules 3, 5 can be implemented not only with the above-described advantageous embodiments but also by any other known method.

The manufacture of the first module 3 is preferably started by deposit- ing a first plating layer on the first substrate 1 by evaporation or by another suitable method. Thus, for example copper or aluminium are used in the evaporation of the first plating layer, and the thickness of evaporation is typically in the order of 100 to 500 nm. In the next step, the first plating layer is provided with the printing of a so-called electrolytic resist, for example by gravure printing. This electrolytic resist has such a pattern that an electrolytic resist is applied at those points in the first module 3 in which no conductive agent should be left, such as a conductor, a coil or a capacitor plate.

After this, the depositing of the conductors can be preferably performed by electrolysis. At this stage, in those parts of the plating layer which do not contain the electrolytic resist, a second plating layer is formed by electrolysis. After this, the desired conductive pattern is formed onto the first plating layer of the product sensor, although still short-circuited by the first plating layer at this stage.

After the depositing stage, the electrolytic resist and the superfluous part of the first plating layer under the electrolytic resist remain to be removed. When aluminium has been used at the depositing stage, both the electrolytic resist and the plating layer can be removed for example with lye. If copper has been used as the evaporating substance, the removal, or etching, of the evaporated plating at the electrolytic resist can be performed in a separate bath in a way known as such. After the removal of superfluous metal, the first module 3 is ready for use as a component for the product sensor 2. In the example of Fig. 1a, this first module 3 is provided with a coil L, one plate 6a, 6b for two capacitors 01 , C2, as well as the necessary wirings to couple the coil L and the capacitor plates 6a, 6b to each other.

In some applications, wirings and/or other electrical couplings can also be formed on the other side of this first substrate 1. These can be formed either in a two-layer process in connection with the above-presented steps, or in a separate step. When applying the two-layer structure, e.g. the capacitor can be implemented in connection with this first substrate 1.

Figures 4a to 4g show different steps of manufacturing the second module 5 of the invention in a cross-section at A-A in Fig. 1b. In this context, it should be mentioned that, for the sake of clarity, the cross- sections shown in Figs. 4a to 4g do not necessarily have the correct dimensions, and in practical applications, the thicknesses of the different layers can differ from each other even to a great extent. The second module 5 can be manufactured, for example, by using a subtrac- tive manufacturing method, such as the etching technique. This second module 5 is provided with at least one fuse F. The steps of manufacturing the fuse module are shown in Figs. 4a to 4g. The manufacturing process is started by forming a plating layer, for example, in the same way as described above in connection with the plating layer of the first module 3. In other words, the surface of the substrate material 4 is provided with a plating layer 8, for example, by evaporation (Fig. 4a), which plating layer 8 is preferably of copper and has a thickness typically in the order of 100 to 300 nm.

In the next step (Fig. 4b), the printing of an electrolytic resist 9 is applied onto the plating layer, preferably by the Flexo printing technique, by using an UV Flexo printing ink. The printing of the electrolysis can also be implemented, for example, by the gravure printing technique, by the screen printing technique, or by another printing method known as such. As in the connection of the module 3, the electrolytic resist 9 is patterned so that the electrolytic resist applied on those parts where there is no conductive substance in the finished product sensor. In the module 5, the parts containing conductive substance correspond, for example, to the fuse or the capacitor.

Next (Fig. 4c), a fuse mask 11 is applied on the surface of the plating layer at the location in which the fuse F is to be implemented. In some applications, it is also possible to use more than one fuse, wherein a fuse mask is formed in a corresponding manner at the fuses in which these fuses are to be formed.

After this, the conductors can be deposited, preferably by electrolysis. At this stage (Fig. 4d), those parts of the plating layer 8 which do not contain an electrolytic resist 9 or a fuse mask 11, a second plating layer 7a, 7b is formed as a result of the electrolysis.

In the step of Fig. 4e, the electrolytic resist 9 as well as the superfluous metal of the plating layer 8 are removed. If copper is used as the evaporating substance, the removal, or etching, of the plating at the electrolytic resist can be performed in a separate bath in a way known as such.The fuse mask 11 is made of a material that withstands the effect of the substance removing the electrolytic resist, wherein the part of the first plating layer 8 at the fuse mask 11 is not decomposed.

If necessary, the fuse mask 11 can still be removed from the second module 5 in such a way that the rest of the electric couplings of the second module 5 are not affected to a significant extent (Fig. 4f).

One advantageous last step in the manufacture of the module 2 according to the invention (Fig. 4g) is the attachment of a thermoplastic film 10. The thermoplastic film 10 is preferably attached on the side of the substrate with the conductive metal coatings 7a, 7b. Lamination with the thermoplastic film provides the final attachment and protection of the fuse. The attachment of the thermoplastic film 10 can be made by a method known as such, for example by transfer lamination or by extrusion. The module 5 is coated preferably throughout with the ther- moplastic film 10. Therefore, one should note that the width of the thermoplastic film 10 is preferably substantially equal to the width of the second module 5. In the finished product sensor 2, the thermoplastic film 10 is thus intended to be placed substantially completely in the area left between the first 3 and the second module 5. Figure 4g shows the second module 5 when finished. The second module 5 comprises a fuse F, second plates 7a, 7b of the capacitors C1, 02, as well as the necessary wirings to couple the fuse and the capacitor plates to each other in an expedient manner.

In another advantageous embodiment of the invention, the lamination of the thermoplastic film 10 is performed in a step of combining the modules 3, 5, which will be described in the following.

In this module combining step, the aim is to combine the first 3 and the second module 5 to produce a finished product sensor 2. In this context, reference is made to Fig. 6 which shows this module combination step in a reduced manner. Let us assume that the first 3 and second modules 5 are manufactured as a long (continuous) web, wherein said web comprises modules 3, 5 one after another and/or next to each other. In Fig. 6, the first web CW comprises first modules 3 and, correspondingly, the second web FW comprises second modules 5. For example, a thermoplastic film 10, which is also fed preferably as a separate web, is placed onto the surface of the first web CW. The attachment can be made by a method known as such, for example by transfer lamination or extrusion. This step is represented by arrow C in Fig. 6. Next, the second web FW is placed onto the thermoplastic film 10 (arrow D). Consequently, in this step, the second web FW is attached by means of the thermoplastic film 10 onto the surface of the first web CW, wherein the electrical couplings intended for the product sensors 2 are provided at the joined modules 3, 5. The webs CW, FW must be aligned with each other as precisely as possible so that the functionality of the coupling is sufficiently reliable. However, this alignment can be implemented relatively easily in the above-described module combination step.

The width of the thermoplastic film web is preferably substantially the same as the width of the first web CW. However, it should be noted that if the widths of the first 3 and the second module 5 are not equal in the direction perpendicular to the travel direction of the web, the width of the thermoplastic web in the direction perpendicular to the travel direction of the web is preferably substantially equal to the width of the overlapping areas of the first 3 and the second module 5 in the finished product sensor 2. Consequently, the thermoplastic film 10 is to be placed between the first 3 and the second module 5 preferably substantially in this whole area left in between.

To implement the coupling of Fig. 5, no electroconductive connection is needed between the first 3 and the second module 5, but the coupling is formed by means of the capacitors C1, C2. The first plate 6a, 6b of the capacitors C1, C2 is formed in the first module 3, and the second plate 7a, 7b is formed in the second module 5. Thus, when the mod- ules 3, 5 are in their place, these different capacitor plates 6a, 7a; 6b, 7b are aligned with each other. As the thermoplastic film 10 is dielectric at least at these capacitor plates, the capacitors C1, C2 are thus formed at these locations. Figure 2 shows a side view of the finished product sensor 2, in which the modules 3, 5 are connected to each other. In this embodiment, such a thermoplastic film 10 is used which is dielectric throughout.

Hereinabove, the connection of the modules 3, 5 in a contactless manner has been described. In this way, junction resistances of the contacts are avoided. Figures 3a and 3b show the modules 3, 5 of such a product sensor 2 in which a contact is made between the modules 3, 5 to form an electrical resonance circuit.

In such applications, in which an electroconductive connection is needed between the modules 3, 5, it is possible to use such a thermoplastic film which is electroconductive or which has been formed to be electroconductive at least in the necessary locations (Fig. 3c). Some examples of such thermoplastic films to be mentioned in this context include 8773 and 8783 (Z-Axis Adhesive Films 8773 and 8783). As a result of compression, these films are electroconductive in the thickness direction only, not in the direction of the plane. Such thermoplastic films, treated to be electroconductive, are called anisotropic conductive films (ACF). Thus, even if the thermoplastic film 10 is placed against the surface of the module 3, 5, it will not affect the internal couplings in the same module 3, 5 but only the couplings between the modules 3, 5. Even though contact junctions were needed between the modules 3, 5, the junction resistances can be made relatively low. Typically, a resistance value lower than 0.5 Ω can be achieved for a junction area of 2 mm x 2 mm. The thermoplastic film 10 can be placed substantially throughout onto the surface of the module. Thus, the film must be compressed to be conductive only partially at desired locations. The thermoplastic film 10 can be placed at only certain points on the surface of the module, wherein the compression of the modules can be implemented substantially throughout by leading the film and module webs through a pressing nip.

If necessary, the thermoplastic film 10 can also be provided with openings at those locations in which no coupling is to be formed between the modules. In this case, for example an isotropic conductive paste can be dispensed into the opening in question. Another alternative is to coat the thermoplastic film 10 with a dielectric material in such locations which should not have any electroconductivity or in which the electroconductivity should be as low as possible.

The actual attachment of the modules 3, 5 to each other is made by heating the thermoplastic film 10 and by applying pressure on the film, if necessary. By the effect of heat, the thermoplastic film 10 becomes softer. After the heating, the thermoplastic film 10 is cooled, wherein the thermoplastic film 10 is hardened and forms a strong mechanical bond between the first 3 and the second module 5.

After the combination of the modules 3, 5, finished product sensors 2 have been formed, which comprise the desired electrical circuit. This electrical circuit comprises, for example in anti-theft applications, an RLC circuit. The coil L is a planar wire loop, and the capacitor C consists of two or more substantially planar plates, which is known as such.

In the manufacturing method according to another advantageous embodiment of the invention, the fuse F is formed in the second module 5 preferably in the following way. The surface of the second module is provided with the necessary wirings and the capacitor plate(s) 7a, 7b, for example, by etching. At the location where the fuse is to be made, the conductor is, however, cut off. After this, an evaporation mask is pressed on the surface of the second module 5, except for the point where the fuse F is to be evaporated. Next, the fuse is evaporated e.g. with copper or aluminium. After this, the second module 5 can be provided with the other necessary layers, and the modules can be combined. It is obvious that the fuse can also be made by another way known by a person skilled in the art.

Although a method has been presented above, in which the modules are manufactured in a web, it is obvious that other methods can also be applied in the manufacture of the modules 3, 5. However, it is essential that the modules are connected to each other by means of a thermoplastic film 10 or the like, and that the first module 3 comprises the coil L and the second module 5 comprises the fuse F.

The connection of the modules to each other can also be made in an- other way than by means of the thermoplastic film 10. For example, the modules 3, 5 can be glued to each other with a lamination glue with little losses, or by using extrusion lamination or an isotropic or anisotropic conductive paste. In this case, the paste can be dispensed, for example, at the same time when the module is connected to an antenna web.

Figures 7 and 8 further show some advantageous embodiments of the product sensor according to the invention. The module 5 in Fig. 7b comprises a fuse F and a chip CH. From Figs. 7a and 7b, it can also be seen that the module 5 has a size different from that of the module 3. Figure 7c shows the combination of the modules 3, 5 according to this embodiment. Figure 8c shows yet another advantageous embodiment to combine the modules 3, 5. Here, the module 5 is connected to that side of the substrate material 1 of the module 3 which is without the coil L. In these embodiments, the dielectric used for the capacitors C1 , C2 is the substrate material 4 of the module 5 and the substrate material 1 of the module 3, as shown in Figs. 7c and 8c, respectively. It is obvious that by combining these and different above-described embodiments, it is possible to achieve various embodiments of the invention which comply, as such, with the spirit of the invention. Therefore, the embodiments of the invention can vary within the inventive features to be presented in the claims below.

The method according to the invention can be divided, for example, according to the structure of the capacitors 01, C2. Hereinabove, the structure with two capacitors in series has already been described (Figs. 2, 7, 8). In this case, the dielectric used for the capacitor was a layer between the modules which, in the above-described example of Fig. 2, was formed by means of the thermoplastic film. Other possibili- ties include the use of the substrate 1 , 4 for the first 3 and/or the second module 5 (Figs. 7, 8), a printed dielectric layer, a transfer laminated dielectric film, and/or an extruded dielectric layer. In the above- presented alternatives, it was possible to use a contactless coupling between the modules 3, 5. However, if there is only one capacitor, one electric coupling can be implemented in a contactless manner by means of the capacitor plates, wherein another coupling is imple- mented by forming an electroconductive contact between the modules 3, 5. In this case, the dielectric layer of the capacitor can be implemented in a way similar to that above. The electroconductive contact can be formed in the second coupling, for example, by means of a two-sided structure either in the first 3 or the second module 5, or by forming a mechanical contact through the substrate either in the first 3 or the second module 5. It is also possible that the conductive contact is formed by means of a printed, transfer laminated or extruded dielectric, which dielectric is preferably undersized so that it does not extend at least completely between the second contact. In this context, it is also possible to use an anisotropic conductive (e.g. 3c; 12) or isotropic conductive paste at the second contact. Yet another alternative to implement the capacitor (capacitors) is to use a separate component, wherein contact couplings are formed between the modules 3, 5. The capacitor(s) can be connected, for example, by the flip-chip technique.

It is obvious that the present invention is not limited solely to the above- presented embodiments but it can be modified within the scope of the appended claims.

Claims

Claims:

1. A method for the manufacture of a product sensor (2), wherein the product sensor (2) is provided with a circuitry pattern to form an electri- cal oscillating circuit (L, C1, C2), and at least one fuse (F) for deactivating the electrical oscillating circuit (L, 01, 02), characterized in forming at least two modules (3, 5), the first module (3) being provided with at least a coil (L) for an electrical resonance circuit, and the second module (5) being provided with at least the fuse, and connecting said at least two modules (3, 5) to each other.

2. The method according to claim 1 , characterized in that said at least two modules (3, 5) are connected to each other by means of a thermoplastic film (10).

3. The method according to claim 2, characterized in that at least one module (5) is coated substantially throughout with the thermoplastic film (10).

4. The method according to claim 1 , 2 or 3, characterized in that the modules (5) are of different sizes.

5. The method according to claim 4, characterized in that the smaller module (5) is coated substantially throughout with the thermoplastic film (10).

6. The method according to any of the claims 2 to 5, characterized in that the thermoplastic film is cooled to attach at least two modules (3, 5) to each other.

7. The method according to claim 1, characterized in that said at least two modules (3, 5) are connected to each other by means of an isotropic or anisotropic paste.

8. The method according to any of the claims 1 to 7, characterized in that said electrical oscillating circuit (L, C1 , 02) comprises at least two capacitors (01, 02) with two capacitor plates (6a, 7a; 6b, 7b), and that one capacitor plate (6a, 7a) of said at least two capacitors is formed in the first module (3) and the other capacitor plate (6b, 7b) is formed in the second module (5).

9. The method according to claim 8, characterized in that a contact coupling is left unprovided between the modules (3, 5).

10. The method according to any of the claims 1 to 9, characterized in that at least one contact coupling is provided between the modules (3, 5).

11. The method according to claim 10, characterized in that said at least one contact coupling is provided by using a thermoplastic film for the connection of the modules, the film being electroconductive sub- stantially in the thickness direction of the film only.

12. The method according to any of the claims 1 to 11, characterized in that different substrate materials are used in the first module (3) and in the second module (5).

13. The methQd according to any of the claims 1 to 12, characterized in that the modules (3) are connected in a substantially continuous manner.

14. A product sensor (2) comprising an oscillating circuit (L, 01, C2) formed by circuitry patterns, and at least one fuse (F) for deactivating said electrical oscillating circuit (L, 01, C2), characterized in that the product sensor (2) comprises at least two modules (3, 5), the first module (3) being provided with at feast a coil (L) for an electrical resonance circuit, and the second module (5) being provided with at least the fuse, and that said at least two modules (3, 5) are connected to each other.

15. The product sensor (2) according to claim 14, characterized in that said at least two modules (3, 5) are connected to each other by means of a thermoplastic film (10).

16. The product sensor (2) according to claim 15, characterized in that said at least one module (5) is coated substantially throughout with the thermoplastic film (10).

17. The product sensor (2) according to claim 14, 15 or 16, characterized in that the modules (5) are of different sizes.

18. The product sensor (2) according to claim 17, characterized in that the smaller module (5) is coated substantially throughout with the thermoplastic film ( 10) .

19. The product sensor (2) according to claim 14, characterized in that said at least two modules (3, 5) are connected to each other by means of an isotropic or anisotropic paste.

20. The product sensor (2) according to claim 14, 15 or 19, characterized in that said electrical oscillating circuit (L, C1, 02) comprises at least two capacitors (C1 , C2) with two capacitor plates (6a, 7a; 6b, 7b), one capacitor plate (6a, 7a) of said at least two capacitors being formed in the first module (3) and the other capacitor plate (6b, 7b) being formed in the second module (5).

21. The product sensor (2) according to claim 20, characterized in that a contact coupling is left unprovided between the modules (3, 5).

22. The product sensor (2) according to any of the claims 14 to 21, characterized in that at least one contact coupling is provided between the modules (3, 5).

23. The product sensor (2) according to claim 22, characterized in that said at least one contact coupling has been provided by using a thermoplastic film for the connection of the modules, the film being electroconductive substantially in the thickness direction of the film only.

24. The product sensor (2) according to any of the claims 14 to 23, characterized in that different substrate materials are used in the first module (3) and in the second module (5).