DE202014001474U1 - UHF RFID transponder - Google Patents

Abstract

UHF RFID transponder based on a printed circuit board, designed for attachment to electrically conductive surfaces, in particular for use on metallic objects, characterized in that the transponder has a total of three substrate layers (5; 6) and two metallic layers (2; 3) designed as a dielectric , which are arranged in such a way that two outer substrate layers (5) configured as dielectric are assigned to the outward-facing surfaces of the upper metallic layer (2) or the lower metallic layer (3) and that an inner substrate layer (6 ) is arranged between the inwardly facing surfaces of the upper (2) and lower metallic layer (3), an RFID chip (1) being assigned to the upper or lower metallic layer (2; 3) and being in the inner as Dielectric-designed substrate layer (6) vias (4) for through-plating between the upper (2) and the lower en metallic layer 3 are arranged.

Description

The invention relates to a PCB-based UHF RFID transponder, designed for mounting on electrically conductive surfaces, in particular for use on metallic objects.

RFID systems enable wireless data transmission between a preferably UHF-based RFID transponder and a data acquisition or evaluation unit, so that parameters of technical objects can be detected without direct access to these objects. This is advantageous for numerous applications in which direct access is not possible or only possible to a limited extent due to cost (for example reduction of personnel) and / or functional aspects (eg detection of machine parameters during operation). Such UHF RFID transponders are used, for example, for access control, for ticket systems, for warehousing, for logistics tasks or for electronic payment systems. The necessary assemblies are both stationary mounted on buildings, machinery, vending machines and the like as well as in mobile equipment such as vehicles, waste containers and the like structurally integrated. These technical systems are therefore operated in very different environments, so that the design of the RFID transponder should be designed so that they can be easily integrated into the associated device technology and function optimally regardless of the specific installation conditions. These requirements have led to a barely manageable number of technical solutions that have been modified for specific applications and of which only three typical application examples are named below:
So describes DE 20 2011 000 794 U1 a load-carrying part for applications in lifting and conveying technology equipped with an RFID transponder system. Thus, the application of force can be detected to avoid critical overloads of this load-receiving part.

Out DE 20 2007 004 382 U1 is a multi-purpose key fob known, which is equipped in addition to the actual function with a tool and a bottle opener. Furthermore, an RFID transponder is integrated, which should facilitate recovery especially in the event of loss of this key fob.

Subject of DE 20 2008 009 016 U1 is a device for mounting RFID transponders on rotating metal parts with differently oriented sections. These are z. As spindles for receiving raw material, semi-finished or tools on metalworking machinery. Here, the RFID transponders are used as identification means in order to be able to document with which tools the respectively processed workpiece has come into contact. Thus, it is primarily in automatic production processes comprehensible whether the necessary tools for a particular processing have actually been used.

Although UHF RFID transponders have basically proven themselves and are now used for a barely manageable number of applications, there is still a need for development. For example, secure solutions for the arrangement of UHF RFID transponders on surfaces of electrically conductive materials are sought. Because of the arrangement on metallic objects an already tuned RFID antenna can be detuned, so that this module does not work on the pre-defined operating point. As a result, the functionality can be impaired by the RFID antenna z. B. the energy available per se is no longer completely usable.

Likewise, the UHF RFID transponders, despite their relatively low useful frequency, have a small size and can easily work on metallic objects.

The size of these transponders is essentially determined by the size of the antenna. In the publication of M. Hirvonen, P. Pursula, K. Jaakkola, and K. Laukkanen, "Planar inverted-F antenna for radio frequency identification" Electron. Lett., Vol. 40, pp. 848-850, Jul. 2004 , describes a method in which the size of the transponder can be reduced by using a "Planar inverted-F antenna" (PIFA). Usually, the length of a PIFA is about λ / 4. In addition, it is possible to reduce the size of an RFID antenna by using a so-called "meander structure" in which the antenna is folded several times. This principle is in the publication "Antenna Design for UHF RFID Tags: A Review and a Practical Application" by IEEE Transactions on Antennas and Propagation, Vol. 12, Dec. 2005 described. With these two methods, it is basically possible to reduce the antenna size of a UHF RFID transponder to be arranged on a metallic surface. Although a combination of both methods allows further reduction, there is still a need for even smaller structures.

The object of the invention is therefore to provide a UHF RFID transponder, which is very small in size and inexpensive to manufacture and which is particularly suitable for use on metallic objects.

This object is achieved in that the transponder a total of three as a dielectric have configured substrate layers and two metallic layers, which are arranged such that two respective outer dielectric layers configured as substrate layers are associated with the outwardly facing surfaces of the upper metallic layer and the lower metallic layer and that an inner designed as a dielectric substrate layer between the inside directed surfaces of the upper and lower metallic layer is arranged. Furthermore, an RFID chip is assigned to the upper or lower metallic layer, vias being arranged in the inner dielectric layer for the through-connection between the upper and lower metallic layers. Advantageous embodiments are described in the subclaims, which are explained in more detail in the exemplary embodiment.

The technical solution according to the invention relates to a UHF RFID transponder for use on metallic objects. This transponder is based on multi-layer printed circuit boards and thus enables cost-effective production. By arranging the metallization layers of the transponder antenna and the actual RFID chip between dielectric layers, an effective protection of these sensitive components against mechanical and electrical loading is achieved, so that the entire UHF RFID transponder is characterized by robustness in outdoor use.

The antenna structure is preferably designed as a "meander PIFA" known per se, so that the transponder can be dimensioned small overall. In this case, only two metallization layers are formed, which are positioned between three electrically insulating substrate layers. The necessary PIFA vias are realized with so-called vias between the two metallization layers. Thus, an antenna is created that can be fully realized by a circuit board manufacturing process.

An embodiment of the present invention is explained below with reference to the drawing, wherein the basic structure of a UHF RFID transponder according to the invention in the single 1 is shown in more detail in exploded view.

As a result, the UHF RFID transponder consists of an RFID chip 1 , made of a metallic upper layer 2 and a metallic lower layer 3 , Furthermore, a total of three substrate layers 5 and 6 intended. In this case, two are each outer substrate layers 5 the outwardly facing surfaces of the metallic upper layer 2 or the metallic lower layer 3 assigned. An inner substrate layer 6 is between the inwardly facing surfaces of the metallic upper layer 2 and the metallic lower layer 3 arranged.

In the inner central substrate layer 6 are several vias 4 arranged, the functionally a via between the metallic upper layer 2 and the metallic lower layer 3 cause.

The RFID chip 1 is in the illustrated embodiment, the metallic upper layer 2 also associated with tuning bars 7 is designed. These tuning bars 7 allow a precise adjustment of the resonance frequency. Unless the RFID chip 1 alternatively the metallic lower layer 3 is assigned, are the Abstimmstegen 7 in this layer 3 designed.

A UHF RFID transponder according to 1 is effectively protected against mechanical and electrical loading and can be further developed in additional manufacturing processes. For example, this UHF RFID transponder can be encapsulated or overmolded with a potting compound. Thus, even better protection and even better attachment to other materials or surfaces are achieved.

LIST OF REFERENCE NUMBERS

1

RFID chip

2

upper metallic layer

3

lower metallic layer

4

vias

5

outer substrate layers designed as a dielectric

6

inner designed as a dielectric substrate layer

7

Abstimmstege

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 202011000794 U1 [0002]
• DE 202007004382 U1 [0003]
• DE 202008009016 U1 [0004]

Cited non-patent literature

• M. Hirvonen, P. Pursula, K. Jaakkola, and K. Laukkanen, "Planar inverted-F antenna for radio frequency identification" Electron. Lett., Vol. 40, pp. 848-850, Jul. 2004 [0007]
• "Antenna Design for UHF RFID Tags: A Review and a Practical Application" by IEEE Transactions on Antennas and Propagation, Vol. 12, Dec. 2005 [0007]

Claims (6)

PCB-based UHF RFID transponder, designed for mounting on electrically conductive surfaces, in particular for use on metallic objects, characterized in that the transponder has a total of three substrate layers configured as a dielectric ( 5 ; 6 ) and two metallic layers ( 2 ; 3 ), which are arranged such that two respective outer substrate layers configured as a dielectric ( 5 ) the outwardly facing surfaces of the upper metallic layer ( 2 ) or the lower metallic layer ( 3 ) and that an inner substrate layer configured as a dielectric ( 6 ) between the inwardly facing surfaces of the upper ( 2 ) and lower metallic layer ( 3 ), wherein an RFID chip ( 1 ) of the upper or lower metallic layer ( 2 ; 3 ) and wherein in the inner designed as a dielectric substrate layer ( 6 ) Vias ( 4 ) to the via between the upper ( 2 ) and the lower metallic layer 3 are arranged. UHF RFID transponder according to claim 1, characterized in that on the RFID chip ( 1 ) associated upper or lower metallic layer ( 2 ; 3 ) Tuning Bars ( 7 ) are configured. UHF RFID transponder according to claim 1, characterized in that the antenna of the transponder is designed as a "meander PIFA antenna". UHF RFID transponder according to claims 2 and 3, characterized in that the tuning bars ( 7 ) between the contours of the "Meander PIFA antenna" are configured. UHF RFID transponder according to claim 1, characterized in that the transponder has a length of 20.0 to 50.0 mm, a width of 10.0 to 30.0 mm and a height of 0.2 to 5.0 mm having. UHF RFID transponder according to claim 1, characterized in that the transponder is encapsulated or encapsulated with a potting compound.

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