Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/12—Supports; Mounting means
  • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
  • H01Q1/2208—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems
  • H01Q1/2225—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
  • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
  • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
  • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
  • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
  • G06K19/077—Constructional details, e.g. mounting of circuits in the carrier
  • G06K19/07749—Constructional details, e.g. mounting of circuits in the carrier the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/36—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith
  • H01Q1/38—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith formed by a conductive layer on an insulating support
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q7/00—Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
  • H01Q7/005—Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop with variable reactance for tuning the antenna

Definitions

• the subject of the present invention is a capacitive antenna and a method for producing such an antenna. It finds more particularly its use in the field of applications related to wireless communication technologies, in particular to radio frequency identification (RFID) applications.
• RFID radio frequency identification
• These applications are, for example, implemented for automatic identification and transmission of data in the fields of access control as well as electronic data management.
• the applications are for example in the context of public transport tickets, highway tolls, parking tickets, plane tickets. Many companies have also developed means of identifying their staff, or their customers, by contactless smart card.
• the mobile device generally comprises a support on which are presented an electronic device for processing, storing and processing information, for example a chip, and the first antenna with which the device is connected. It is generally in the form of a credit card in ISO format or a flexible tag ("Tag").
• the price of a chip is proportional to the surface area of silicon used to house the microprocessor, memory areas and capacitors.
• the size of the chip By significantly reduce the cost of the antenna and the micropackaging of the chip, it is known in the state of the art to seek to reduce the size of the chip by reducing the size generated by the capacitors. Chips are therefore used comprising capacitors of small bulk and having lower capacities.
• L a corresponds to the inductance of the antenna
• C p corresponds to the capacity of the device
• the antenna is screen printed on a support. Generally, the antenna has several turns so that the first pad of the antenna is inside the turns, while the second pad of the antenna is outside the turns. To connect the chip and the second capacitor in parallel with the antenna, it is necessary to connect the capacitor to each of the two pads of the antenna.
• the problem is essentially posed in the state of the art by the fact that the antenna necessarily comprises several turns, given the capacities of the capacitors and the law of resonance to be respected.
• the second capacitor is screen printed outside the center of the turns to avoid damaging the flux passing through and therefore the inductance of the antenna.
• this second capacitor is easily connected to the external stud of the antenna.
• To connect it to the interior stud of the antenna it is necessary to make an insulating bridge above the turns at the level of which a conductive connection can then be screen printed.
• the realization of this bridge is restrictive and adds additional steps to the manufacturing process of the antenna.
• the capacitors that can be obtained have an intermediate capacity. This capacity does not fully complement the decrease in the internal capacity of the chip. Consequently so that the law of resonance is respected, it is necessary to increase the inductance of the antenna, which is obtained by increasing the number of turns, and by imposing the realization of a bridge to connect this antenna multispires with the second screen-printed capacitor.
• capacitors which have a higher capacity and which could cooperate with a single coil antenna. But in this case such capacitors are expensive, bulky and reduce efforts to reduce costs.
• the object of the invention is to solve the problems mentioned and makes it possible to manufacture planar antennas at low cost and in large volume taking into account the future technical constraints imposed by the chip manufacturers. According to the invention it is possible to propose on the same support an antenna preferably comprising a single turn, this antenna being connected to a high capacity capacitor.
• C is the value of the capacitance
• ⁇ 0 corresponds to the dielectric permittivity of the vacuum (8.854. 10 12 F / m)
• 8 r corresponds to the relative permittivity of the dielectric
• S corresponds to the surface of the electrodes opposite from each other
• e corresponds to the thickness of the dielectric.
• a high-capacity capacitor is obtained by playing mainly on the value of the thickness of dielectric which is arranged between the two conductive plates.
• the capacitor is printed by gravure printing on the support also having the antenna. Indeed, by the gravure technique, we obtain the deposition of very thin layer.
• the capacitor is obtained by depositing at least three superimposed and successive layers, such as a first conductive layer, covered with a second insulating layer, and finally itself covered with a third conductive layer.
• the antenna can itself be printed by gravure printing on this occasion, the design of the antenna being finalized with the two conductive layers.
• Rotogravure is a technique derived from intaglio printing.
• the printing elements are recessed.
• the printing areas are engraved on a steel cylinder covered with copper and chrome. Chemical solutions can be used to etch copper.
• Another method of preparing the printing cylinders uses a laser for engraving. When printing, the ink fills the cells of the cylinder; a doctor blade removes the excess ink and the support is then pressed against the printer form to make the print. The resulting print is of high quality and is perfectly reproducible.
• Gravure printing uses fluid inks containing volatile solvents. Even for thin deposits, a deposit is obtained which covers the entire surface to be printed uniformly.
• the advantages linked to this process make it possible to guarantee a constant geometry of the planar capacitor. Due to the fact that this capacitor has a high capacity, even a single coil antenna is tuned to the resonance. Therefore the capacitor and the chip can be very easily connected to the single coil antenna.
• the overall electrical resistance of the monospire antenna is lower than the resistance of a conventional spiral. This makes it possible to envisage, in a variant, a deposition of high-speed electrolytic copper with a constant and controlled thickness, above each of the zones having a portion of conductive layer.
• the inventive method makes it possible to very significantly reduce the price of the transponder by playing both on the direct cost of manufacturing the antenna and on the simplification of the micropackaging of the chip.
• the subject of the invention is a coupling antenna comprising at least one turn presented on a support, and connected to a capacitor presented on this same support, the capacitor being mounted in parallel on two pads of the antenna, characterized in that the the antenna and the capacitor are printed by gravure printing on the same support.
• the invention also relates to a method for producing an antenna comprising at least one turn connected to a capacitor, the antenna and the capacitor being presented on the same insulating support, characterized in that it comprises the following steps:
• FIG. 1 a a top view of a support after a first step of the method according to the invention
• FIG. 1 b a top view of a support after a second step of the method according to the invention
• FIG. 1 c a top view of a support after a third step of the method according to the invention
• FIG. 1d a top view of a support after an optional last step of the method according to the invention
• FIG. 2 shows a nomadic device 1 provided for exchanging radioelectric signals with a reading device 2.
• the nomadic device 1 is a transponder comprising an electronic microcircuit 3, or chip 3, and an antenna 4.
• the chip 3 and the antenna 4 are presented on an insulating substrate 5.
• This substrate 5 can for example have the shapes of a smart card standardized in ISO format.
• the chip 3 is connected to the antenna 4, and is supplied by the induced current produced by the electromagnetic field emitted and received in the antenna 4.
• the reading device 2 comprises a second antenna 6 for transmitting and receiving signals towards the nomadic device 1. Furthermore, the device 2 comprises a coupler 7 connected to the second antenna 6, this coupler 7 being moreover connected to a unit 8 for processing and managing the data exchanged.
• the unit 8 is for example a computer.
• the antenna 4 comprises, as shown in FIGS. 1a, 1b, 1c and 1d, at least one turn 9 and a capacitor 10 mounted in parallel with the turn 9.
• the turn 9 and the capacitor 0 are shown on a support 11.
• the support 11 is insulating and may for example be in the form of a flexible thin film.
• the substrate 11 is of polyethylene (PE), polyester (PET), polyvinyl chloride (PVC), polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS), glass-epoxy, polyimide, paper, etc. type.
• the coil 9 comprises a first pad 12 and a second pad 13 to which the capacitor 10 and the chip 3 will be connected.
• the support 11 is placed under a first gravure cylinder supplied with electroconductive ink.
• a first pattern is thus produced drawing the turn 9, a lower electrode 14 of the capacitor 10, and a connection 15 between the first pad 12 and the lower electrode 14.
• the second pad 13 is already apparent from the deposition of the first layer d conductive ink.
• the thickness of the ink deposit, once dried, is of the order of 2 to 4 micrometers.
• a second layer 16 is deposited with a dielectric material above the lower electrode 14.
• this second layer 16 is deposited by gravure printing by means of a second cylinder supplied with an ink to the properties insulating.
• this second layer is obtained following a double passage under two cylinders such as the second cylinder.
• the dielectric layer 16 is obtained by two superposed layers of insulating ink. With such a double thickness of the insulating layers, the problems of porosity in the dielectric separating the lower electrode 14 from the upper electrode 17 are avoided.
• the thickness of the insulating layer 16 is less than 10 micrometers, and preferably varies between 5 and 10 micrometers, this layer 16 is preferably obtained in two successive layers in order to limit the porosities generating current leaks.
• the dielectric layer is homogeneous, and does not have pores in which impurities could lodge.
• layer 16 can alternatively be obtained in a single pass under the second cylinder.
• a third layer is deposited, to form the upper electrode 17, and also a connection 18 between this upper electrode 17 and the second pad 13.
• This third layer is printed by gravure printing. using conductive ink. In this case, it is preferable to use a four-color machine having the four cylinders within the same line.
• the same conductive ink is used to make the first layer and the third layer
• the ink used in the invention has very low electrical resistance, it includes copper, silver, gold, palladium. , tin or alloys thereof and conductive polymers.
• the electrically conductive ink must be prepared, from the point of view of its viscosity and from the point of view of other physicochemical properties, so that it is suitable for gravure printing.
• the ink chosen is for example an electroconductive ink charged with metal.
• the metal is mainly silver, and it is presented in the form of flakes forming micro plates. These micro plates are preferably very thin (1 to 2 ⁇ m) and with a length of between 2 and 5 ⁇ m.
• the proportion of these metallic charges is between 50% and 80% of the solid mass of the ink.
• the proportion of metallic charges is 70%, to guarantee a high conductivity of the ink thus formed.
• the high conductivity ink is in return for low resistivity, which facilitates the next metallization step.
• the ink may include conductive organic polymers.
• the advantage of these polymers is that they are formulated in a solvent or aqueous phase which thus makes it possible to adjust the rheological properties of the ink obtained, to make it in particular compatible with the gravure process.
• Another advantage comes from the fact that in this variant, the ink does not contain metallic fillers, which contributes to a large-scale cost reduction, and which facilitates obtaining a homogeneous ink making the process more reliable. Manufacturing.
• a metal layer 19 to cover all the portions having conductive ink, whether it is from the first pass or the third pass.
• This metal layer can be deposited by electrolytic copper plating.
• the thickness of copper deposited is of the order of 5 micrometers and covers the turn 9, the studs 12 and 13 the connections 15 and 18, and also the upper face 17 of the upper electrode of the capacitor 10.
• a coil 9 with a width of 500 ⁇ m is chosen such that it has an inductance of 270 nH.
• the capacity of the external planar capacitor 10 is determined which must be provided on the support 11.
• a diameter of the electrodes equal to 11.8 millimeters is chosen.
• the capacity of the chip 3 is 25 pF, then it is necessary for the planar capacitor 10 to have a capacity of 485 pF, and for this purpose, when a dielectric thickness of 8 millimeters is obtained, we provides a capacitor area such that the diameter is 12.8 millimeters.

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• Engineering & Computer Science (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Theoretical Computer Science (AREA)
• Details Of Aerials (AREA)
• Printing Methods (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=30011489

Family Applications (1)

Country Status (8)

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Family Cites Families (4)

• 2002
  • 2002-07-25 FR FR0209462A patent/FR2842950B1/fr not_active Expired - Fee Related
• 2003
  • 2003-07-24 WO PCT/FR2003/050020 patent/WO2004012299A2/fr not_active Ceased
  • 2003-07-24 EP EP03755657A patent/EP1527499A2/de not_active Withdrawn
  • 2003-07-24 US US10/521,822 patent/US20060164312A1/en not_active Abandoned
  • 2003-07-24 CN CNA038202484A patent/CN1679208A/zh active Pending
  • 2003-07-24 AU AU2003273499A patent/AU2003273499A1/en not_active Abandoned
  • 2003-07-24 JP JP2004523897A patent/JP2005534243A/ja active Pending
  • 2003-07-24 MX MXPA05000882A patent/MXPA05000882A/es not_active Application Discontinuation

Non-Patent Citations (1)

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