WO2010058068A1

WO2010058068A1 - An identification tag comprising protective features and a method for manufacturing the identification tag

Info

Publication number: WO2010058068A1
Application number: PCT/FI2009/050912
Authority: WO
Inventors: Sami Liponkoski
Original assignee: Upm Raflatac Oy
Priority date: 2008-11-18
Filing date: 2009-11-13
Publication date: 2010-05-27

Abstract

The invention relates to an identification tag (1) attachable to an item (5) comprising an integrated circuit (10) in connection with an antenna (20), the integrated circuit (10) and the antenna (20) being supported by a substantially transparent or translucent substrate (30). The identification tag (1) further comprises a protective dot (15) placed locally over the integrated circuit (10) for protecting the integrated circuit (10) from environmental effects. The present invention also relates to a method for manufacturing such an identification tag (1).

Description

AN IDENTIFICATION TAG COMPRISING PROTECTIVE FEATURES AND A METHOD FOR MANUFACTURING THE IDENTIFICATION TAG

Field of the Invention

The present invention relates to an identification tag comprising an integrated circuit in connection with an antenna. The present invention also relates to a method for manufacturing such an identification tag.

Background of the Invention

A radio frequency identification (later "RFID") tag comprises typically an antenna and an integrated circuit attached to the antenna. The antenna may be manufactured in several additive or non-additive ways as a conductive path on a suitable substrate by using, for example, electroplating, printing etching or die-cutting. RFID tags do not necessarily have an internal power supply or battery of their own but the power required to energize the tag is obtained from the electromagnetic field created by the reader device used to interrogate the tag. Such tags relying purely on backscatter communication are called passive tags. Semi-passive tags may have an internal energy source, which is activated by the reader created field. Active tags have an internal energy source providing energy to the tag and the tag may thus have an stand-alone broadcasting circuitry which can be activated without the presence of the reader field.

RFID tags can be used in various environments where identification is needed. Known applications comprise e.g. theft prevention systems, product identification systems, tracing and tracking systems, access control systems etc. In many applications RFID tags are replacing conventional methods based, for example, on bar codes. The main benefit of RFID tags is that they can be read in wireless manner and from a distance.

One example of product identification relates to a cars or other similar vehicles having a RFID tag comprising data concerning the vehicle in question. In cars, such a RFID tag is usually placed on a windshield and therefore substantial transparency or translucency of the tag is appreciated. However, for road tolling or similar security driven applications, the RFID is not only an identification element but also a security element. Therefore, for some applications it is mandatory to have the antenna and the integrated circuit or at least parts of these visible through the other structures of the tag. This is because in such a way it is possible to more easily detect if the tag has been tampered with.

One possible tamper proof solution is to use a strong adhesive against the glass and when the tag is removed, certain functional parts of the tag break off to the class surface. As a result of this the tag ceases to function electrically becoming disabled. If the tag is made with substantially transparent structure, any attempt to tamper with the tag becomes more evident.

The integrated circuit chips, ICs, used in RFID tags are known to be sensitive to the sunlight, and especially to UV part of the radiation. The sunlight weakens the operation of the integrated circuit by, among other effects, generating leakage current and noise in the circuit. Further, the memory used in the ICs may also be erased by UV radiation. When a RFID tag is placed on e.g. a windshield of a car, the tag is very vulnerable to the sunlight and even if the glass of windshield will filter out UV radiation, still the remaining radiation spectrum (UV, near-UV, visible and infrared wavelengths) can affect the performance of the IC of the RFID tag . Sunlight is not the only environmental factor that may harm the identification tag. Also other factors, such as variation in temperature, humidity etc. may damage the operation of the integrated circuit.

The above mentioned environmental effects can harm a RFID tag by completely disabling the functions of the tags or by reducing the performance of the tag, for example, reducing the maximum reading distance. Therefore, there is clear need for RFID tags with improved protective features to protect the tag against environmental effects, such as aforementioned radiation.

It should be noted that the RFID tags, especially passive tags, rely on very small signal levels. In case of the passive tags these are created only by the reader field which decreases quickly with increasing reading distance. Such small signals are significantly more pronounced to suffer from external environmental interferences compared to traditional electronics. Further, the protection provided by the prior art tag structures against the environmental effects is fairly modest and novel approaches are therefore required.

Summary of the Invention

According to a first aspect of the invention, there is provided an identification tag according to claim 1.

According to a second aspect of the invention, there is provided a method for manufacturing an identification tag according to claim 11.

According to one embodiment, the present invention aims especially to solve the previous problem relating to a substantially transparent identification tags that come in for direct sunlight. The invention proposes a usage of a protecting element for the integrated circuit against radiation, in a way that it also protects especially the integrated circuit, but even the other parts of the transponder from environmental effects. The invention also proposes an inventive process for manufacturing the identification tags comprising such a protective element.

According to another embodiment, the present invention aims towards a multifunctional protection scheme, where in addition to the light radiation (UV) protection, the integrated circuit of the tag but even other parts of the transponder are simultaneously protected against several environmental effects, such as humidity, chemicals, mechanical stresses caused by wide temperature changes and electrostatic discharges (ESDs). Therefore, the invention aims to provide RFID tags that are more durable against harsh environments than prior art tags but at the same time they possess properties, like transparency, that is required for the given application by security or other reasons.

The identification tag attachable to an item according to one example of the invention comprises an integrated circuit in connection with an antenna, said integrated circuit and said antenna being supported by a substantially transparent or translucent substrate, wherein said identification tag further comprises a protective dot placed locally over the integrated circuit for protecting the integrated circuit from environmental effects.

The method for manufacturing an identification tag attachable to an item comprising an integrated circuit in connection with an antenna, said integrated circuit and said antenna being supported by a substantially transparent or translucent substrate, comprises utilizing a quality marking equipment for disqualified tags for marking a protective dot over the integrated circuit.

The identification tag of the present solution has significant advantages over the prior solutions. In addition to the light (UV) exposure, the protective layer - when produced of a carefully selected material or combination of materials - gives protection also against other environmental effects, such as temperature variations, humidity, liquid chemicals or vapours and ESDs. In addition the protective layer may increase mechanical strength of the tag, and - if produced from a rubber like material - still retaining the flexibility of the tag. Similarly, the hardness of the tag may be locally increased, if the protective layer is made of epoxy resin.

An important application for such RFID tags is the windshield tags for vehicles as will be explained in more detail in the following examples. However, the application targets are not limited to only windshields and sunlight, but can be broadened to various situations where RFID tags are exposed to severe environmental effects.

The manufacturing process according to the invention - on the other hand - can be easily carried out by minor modifications to the existing devices and methods.

Description of the Drawings The present invention will be described by way of non-limiting example with reference to the accompanying drawings, wherein:

Figures 1 a, 1 b illustrate schematically an example of a basic structure of an RFID tag according to prior art,

Figures 2a, 2b illustrate schematically an example of an RFID tag comprising a protective dot according to the invention,

Figure 3 illustrates schematically another example of an RFID tag comprising a protective dot according to the invention,

Figures 4a, 4b illustrate schematically an example of a tamper-proof RFID tag comprising a protective dot according to the invention, and

Figure 5 illustrates schematically an example of an RFID tag according to the invention on a windshield of a car.

Detailed Description of the Invention

Figure 1 a illustrates an example structure of an RFID tag 1 in a simplified manner. The RFID tag 1 comprises an antenna 20 to which an integrated circuit 10 has been attached. The antenna 20 may be, for example, printed or etched to a substrate 30. Figure 1 b is a side-view of Figure 1a. In addition to the elements presented in Figure 1 a, Figure 1 b comprises a strong adhesive 50 that is placed against the labelling surface, such as a windshield, in order to affix the tag onto to the surface. Similarly, base 30 in Figure 1 b comprises an optional adhesive 35 for the RFID tag/inlay. This adhesive 35 is used e.g. when the tag/inlay is equipped with further layers, such as printable surface layers and/or tamper-proof elements or similar.

Term RFID inlay is used widely for the core elements of the RFID tag, including typically the substrate 30, antenna 20 and the integrated circuit 10.

This RFID inlay may also be interpreted to include the adhesive layers 50,35 on both or one side of these components. This inlay is usually provided by the RFID supplier to the customer, who then may add necessary printable or other layers to this INLAY structure before the end use application. Normally, the RFID inlay is an entity that has all the electric RFID functionalities available. It is appreciated that, the shape and size of the RFID tag presented in the examples of this application may vary according to its purpose, and therefore the configuration of the RFID tag should not be necessarily interpreted as a limiting feature for the present invention.

Figures 2a, 2b illustrate an RFID tag according to the one example of the invention. What is different to the tag presented in Figures 1 a and 1 b, is that the tag of Figures 2a and 2b comprises a further protective layer according to the invention, also called a protective dot 15, covering the integrated circuit 10 (later "IC"). The shape of the protective layer may be also different from what is presented in figures 2a, 2b.

The protective dot 15 is placed directly over the IC area 10, so that the integrated circuit becomes "hidden" from the radiating UV or near UV light. The dot 15 may be made of different materials - ink, resin, film, adhesive or similar - to cover the immediate area of the IC 10. The material is selected so that it will form a strong enough radiation (UV) barrier around the IC. According to other embodiment of the invention, the material is preferably selected so that it forms a barrier also for humidity, changes in temperature, chemicals or vapour or other environmental effects. If e.g. epoxy resin or rubber is used as a protective material, the integrated circuit will also be mechanically protected. In some applications improved ESD protection is required for the IC to prevent momentary unwanted currents to damage the IC. ESD is a serious issue in solid state electronics. ICs are typically made from semiconductor materials such as silicon and insulating materials such as silicon dioxide. Either of these materials can suffer permanent damage when subjected to high voltages, which may be caused static build up.

Figure 3 illustrates in more detailed manner the structure of the RFID tag having a protective dot 15 covering the integrated circuit 10. In Figure 3 it is shown that also the IC bonding adhesive 12 is covered by the protective dot.

The IC bonding adhesive, which provides both mechanical and electrical contacts between the IC and the antenna/substrate, does not typically tolerate humidity. Prior art solutions to protect this connection from humidity comprise typically laminating the whole transponder with a film to protect the connection. However, as a result of the invention, it possible to cover IC area containing the bonding adhesive strap, module or welded connection with the dot and by that, form a multifunctional barrier both for UV, humidity and mechanical stresses.

The bonding adhesive 12 may be, for example, so called anisotropically conductive adhesive (ACA) that conducts electricity only in z-direction. ACAs have typically two components: conductive particles and adhesive matrix. The conductive particles can be of many types, e. g. metal coated polymer spheres, metal particles or solder material. The adhesive matrix is most often epoxy based. Typically such epoxy based ACAs handle humidity and chemicals well. However, humidity/water connives oxidation in the embedded metals. This means that if the bonding is not dense, the oxidation will occur within the bonding. This increases the resistance of the bonding, and the performance will deteriorate. Usually the bonding is protected by PSA laminate and therefore the effects of random exposure on water can be minimized. This laminate does not, however, protect from sinking, where the water can penetrate the PSA-clue and travel towards the bonding. Common antenna substrate materials are, for example PET and paper. Also other substrate materials can be used, e.g. Pl, PEEK, PC, PVC. Common antenna materials are copper, aluminium, silver paste/ ink.

The bonding connection to be covered by the protective dot according to the invention may also cover straps, module or welded connections as known for a person skilled in the art and used in connection with ICs.

Figure 4a illustrates a tamper-proof tag 2 comprising the protective dot 15 as described above, but also one or more layers 51 that makes the tag tamper- proof. These layers 51 may include tamper proof lacquer, metallic sulphide, hologram, release for splitting the hologram and various chemical treatments. All these one or more layers may be further covered with plastic film, e.g. PET film 52. The tamper-proof layers may be locally adjusted to cover only one part of the RFID tag.

Figure 4b illustrates a tamper-proof tag 2 where the protective dot 15 is attached to the adhesive layer 50 locally by a tamper-proof layer. The antenna 20, on the other hand, is attached to the adhesive layer 50 as usual. Therefore, if the tag is removed, the integrated chip 10 will stay with the adhesive layer 50, whereas the antenna 20 and the substrate 30 will be released.

Based on the description above, it becomes clear for a person skilled in the art that the current invention improves significantly the possibilities to protect the IC in a RFID tag and still maintain the possibility to manufacture substantially transparent or translucent structures as requested in certain specific applications such as the vehicle windscreen tagging.

The invention, with the help of specifically designed dot made of optimally selected material(s) can provide a combination of one or more of the following properties : - protecting the IC from becoming electronically affected by strong sunlight (or other light) and especially the UV part of such radiation

- protecting the connection (bonding adhesive) between the IC and the antenna from moisture

- protecting the connection (bonding adhesive) between the IC and the antenna from mechanical stresses caused by mechanical impact or thermal gradients (thermo-mechanical stress) allowing the forces to be evenly distributed over a larger area

- protecting the connection (bonding adhesive) between the IC and the antenna from degradation over time because of sunlight, thermal gradients or other environmental stresses and without need to cover the whole RFID tag area

- protecting the connection (bonding adhesive) between the IC and the IC itself from ESD damages because of static voltage build up or similar Further, the invention helps to obtain more tamper-proof RFID tag structure, because the specifically designed dot made of optimally selected material(s) can provide :

- possibility to maintain the RFID structure substantially transparent by removing the need to cover whole RFID tag with protective and thick layers

- possibility to use elsewhere, outside the dotted area, thinner and more flexible and/or more transparent structures/layers

- possibility to use the adhesive properties of the dot to cause local destruction of the RFID inlay if the RFID tag is removed from the tagged item, for example from the windshield. These properties of the dot can be used alone or in combination with other adhesive layers to provide tamper-proof structures

The multifunctional protection scheme provided by the protective dot according to the invention provides an economical way to design RFID inlays and RFID tags for various purposes focusing the environmental protection and/or the tamper-evident functionalities to the IC and its neighbourhood without need to oversize the other parts or structures of the RFID product.

It is important to notice, that usually it is the simultaneous effect of several environmental effects that causes a RFID tag to fail or have reduced performance. The invention provides a simple way to protect the RFID tag from all of these without need for extensive measures.

It is also important to notice that any protection needed is placed only certain locations of the RFID tag. This is because a thinness of the tag is highly appreciated. The thinner the RFID tag is, the more difficult it becomes to release the RFID tag from its surface. The prior art solutions relying on thicker protective layer(s) covering the whole area of the tag make it easier to tamper with the tag by aiming to detach it in one piece and undamaged. When the layers can be manufactured thinner, then they are more vulnerable to be harmed if the tag is tampered with. Also the adhesives with suitable bond strength for the anti-tampering can be more readily found if the requirement for bond strength can be reduced. Figure 5 illustrates an example of a use of the RFID tag 1 comprising a protective dot 15. The RFID tag 1 is placed against a windshield 5 of a car. It should be noticed that Figure 5 presents only part 7 of the car. It is appreciated that the RFID tag may also be placed to car's other windows or surfaces instead of the windshield. Instead of a car, the RFID tag may be also used in other situations as well, having similar circumstances (sunlight, changes in temperature, humidity, etc.).

The manufacturing of the RFID inlays comprising the protective dot does not require significant modifications to the existing systems. Before the invention, non-operational, faulty transponders in the RFID inlay production have been marked with an ink dot so that they can be easily removed from the production line. Surprisingly, this same technology may be used for marking the good tags with a protective dot in the inlay process. This means that the existing manufacturing system will be used in reverse compared to the prior procedure. The utilization of the existing system enables production of the tags with protective dots already in the inlay manufacturing phase. This saves the overlay film in the production and the tags can be made more flexible for tamper proof converting.

Referring back to Fig. 2b, the protective dot 15 may be wider than the integrated circuit 10, and the antenna 20 may be wider than the protective dot 15.

The width of the protective dot 15 may be greater than the width of the integrated circuit 10, and the width of the protective dot 15 may be narrower than the width of the antenna 20.

Referring back to Figs. 4a and 4b, the tag 2 may comprise an adhesive layer 50 to be placed against a surface 5 (e.g. a windscreen) to be labelled. The integrated circuit 10 may be located between the protective dot 15 and the antenna 20. The adhesive layer 50, the protective dot 15, the integrated circuit 10, and the antenna may be arranged such that the antenna 20 will be released from the integrated circuit 10 if the tag 2 is removed from said surface 5. Thus, an electrical connection between the integrated circuit 10 and the antenna 20 will be broken upon an attempt to release the tag 2 from the surface 5. This may provide a tamper-evident function.

The integrated circuit 10 may be at least locally attached to the adhesive layer 50 via the protective dot 15 such that a mechanical connection between the integrated circuit 10 and the adhesive layer 50 is stronger than a mechanical connection between the antenna 20 and the integrated circuit 10. If someone tries to remove the tag 2 from the surface 5, the integrated circuit 10 will remain attached to the adhesive layer 50 due to the stronger mechanical bond, but the antenna 20 will be released from the integrated circuit 10 due to the weaker bond.

The antenna 20, together with the substrate 30, may be released from the integrated circuit 10, the protective dot 15, and the adhesive layer 50.

The protective dot 15 may be at least locally attached to the adhesive layer 50 such that the antenna 20 will be released from the protective dot 15 if the tag 2 is removed from said surface 5.

The protective dot 15 may be at least locally attached to the adhesive layer 50 such that a mechanical bond between the adhesive layer 50 and the protective dot 15 is stronger than a mechanical bond between the protective dot 15 and the antenna 20.

In the above, the RFID tag comprising a protective dot was described by way of an example. It is appreciated that the in addition to the examples being disclosed, such an RFID tag may be used in various outdoor situations where the RFID tag will be a target for certain environmental effects. The multifunctional dot may protect the integrated circuit of the tag against these various effects. However, even though such a protective dot is used, the tag still maintains its substantial transparency which is required e.g. for safety reasons.

Claims

Claims:

1. An identification tag (1 , 2) attachable to an item (5) comprising an integrated circuit (10) in connection with an antenna (20), said integrated circuit (10) and said antenna (20) being supported by a substantially transparent or translucent substrate (30), wherein said identification tag (1 ) further comprises a protective dot (15) placed locally over the integrated circuit (10) for protecting the integrated circuit (10) from environmental effects.

2. The identification tag (1 ) according to claim 1 , wherein the protective dot (15) is configured to protect the integrated circuit (10) against at least one of the following: sunlight or other light radiation, changes in temperature, humidity, chemical, vapour or electromagnetic interference.

3. The identification tag (1 ) according to claim 1 or 2, wherein the protective dot (15) is configured to protect the integrated circuit (10) against at least one of the following: mechanical stress or thermo- mechanical stress.

4. The identification tag (1 ) according to any of claims 1 -3, wherein the protective dot (15) is configured to provide a tamper-evident function locally over and near the integrated circuit (10).

5. The identification tag (1 ) according to claim 4, wherein the protective dot (15) provides a locally modified adhesion region over and near the integrated circuit (10) causing the integrated circuit (10) to become broken of from the tag (1 ) if the tag (1 ) is tampered with aiming to remove it from the item (5) that is has been attached to.

6. The identification tag (1 ) according to claim 4 or 5, wherein said tag (1 ) comprises an adhesive layer (50) to be placed against a surface (5) to be labelled, wherein the integrated circuit 10 is attached to the adhesive layer 50 via the protective dot 15 such that the integrated circuit 10 stays with the adhesive layer 50 and the antenna 20 is released from the integrated circuit 10 when the tag 2 is removed from said surface (5).

7. The identification tag (1 ) according to any of the claims 1 to 6, wherein the protective dot (15) is made of one of the following or a combination therein: ink, resin, film, adhesive, epoxy resin, rubber.

8. The identification tag (1 ) according to any of the claims 1 to 7, wherein the identification tag (1 ) is radio frequency identification tag.

9. The identification tag (1 ) according to any of the claims 1 to 8, wherein the protective dot (15) is located directly on the integrated circuit area including the bonding adhesive strap, module or welded connection.

10. The identification tag (1 , 2) according to any of the claims 1 to 9, further comprising additional tamper-proof layers (51 ).

11. A method for manufacturing an identification tag (1 ) attachable to an item (5) comprising an integrated circuit (10) in connection with an antenna (20), said integrated circuit (10) and said antenna (20) being supported by a substantially transparent or translucent substrate (30), said method comprising marking a protective dot (15) locally over the integrated circuit (10) by utilizing a quality marking equipment for disqualified tags in order to mark the protective dot over the integrated circuit (10).