Classifications

• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR 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
  • G06K19/07743—External electrical contacts

Definitions

• Electrical circuit electronic module for smart card made on this electrical circuit and method for producing such an electrical circuit.
• the invention relates to the field of electrical circuits.
• electrical circuits according to the invention may be printed circuits or circuits comprising one or more connection grids made of a sheet of conductive material cut and co-laminated with an insulating substrate.
• Such electrical circuits are used, for example, for making contacts for electronic chip card modules, chip card antennas, mixed circuits comprising both contacts and an antenna, and so on.
• Smart cards have multiple uses: credit cards, SIM cards for mobile phones, transport cards, identity cards, etc. but the invention is of particular interest for the production of printed circuits comprising conductive tracks and / or visible contact areas on the finished product.
• smart cards they usually consist of a rigid support, for example plastic, constituting the main part of the card, in which is incorporated an electronic module manufactured separately.
• This electronic module comprises a generally flexible circuit board provided with a chip (integrated circuit) and means for connecting the chip to a device for reading and / or writing data in the chip.
• connection means - or connectors - are for example contacts consisting of conductive metal tracks flush with the electronic module on the surface of the support.
• the chip card manufacturers wish to match the color of the contacts to the or the colors of the card.
• the contacts are usually covered with a layer of gold, to obtain a golden finish, or a layer of silver or palladium, to obtain a silver finish.
• An object of the invention is to open the range of chemical components that can be used to produce colors for printed circuits comprising conductive tracks visible on the finished product, while retaining appropriate electrical and mechanical properties for their use in electronics. or microelectronics.
• the substrate is a glass-epoxy substrate.
• this substrate is flexible.
• the conductive track is for example made by photo-lithography. That is to say by gluing and laminating a layer of copper on the substrate, in which patterns are then advantageously etched to provide one or more conductive pads that can be used for example as electrical contacts. Alternatively, the patterns are cut before co-laminating with a substrate (so-called "lead frame" technology according to the English terminology).
• the conductive track may also comprise one or more metallization layers (for example, nickel, gold, silver, palladium or an alloy thereof).
• metallization layers for example, nickel, gold, silver, palladium or an alloy thereof.
• the electrical circuit is characterized in that the conductive track is also at least partially covered with a ruthenium layer.
• This ruthenium layer optionally comprising ruthenium oxide, gives a black color, without the addition of coloring particles.
• Ruthenium imparts a black appearance to the conductive layer and since it is also a metal, it gives this layer a conductivity adapted for a good pressure connection between it and a read / write device.
• the ruthenium thickness is advantageously between 5 nanometers and 3 micrometers. A minimum thickness of 25 nm is useful to obtain a uniform black color. With a ruthenium thickness of less than 25 nm, it is possible to obtain iridescent effects. On the other hand, there is little or no interest in depositing more than 3 microns of ruthenium on the conductive layer.
• the invention also relates to an electronic module for a smart card obtained from the electrical circuit characterized above, as well as a method of manufacturing this electrical circuit.
• FIG. 1 shows schematically in perspective a chip card comprising an example of a module according to the invention
• FIG. 2 schematically shows a top view of an electric circuit portion according to the invention
• FIG. 3 shows in section, schematically and partially, an example of a connector for the modules of Figures 1 and 2;
• FIGS. 4a to 4k schematically represent steps of an exemplary implementation of the method according to the invention.
• FIG. 5 schematically represents an example of stack of layers that can be obtained with the method according to the invention, the nature of the layers being specified in the table below.
• a smart card 1 comprises a module 2 with a connector 3.
• the module 2 is generally made in the form of a separate element which is inserted in a cavity in the card.
• This element comprises a generally flexible substrate 4 (see Fig. 2) of PET, glass-epoxy, etc. on which is realized the connector 3, to which is subsequently connected a chip (not shown).
• FIG. 2 illustrates an example of an electrical circuit portion, here a printed circuit board 5, with six connectors 3.
• Each connector 3 comprises a contact pad 8 formed of conductive tracks 6.
• eight electrical contacts 7 are made to from the conductive tracks 6.
• a connector 3 (that is to say essentially a module without a chip) has a multilayer structure formed of the substrate 4, an adhesive layer 9, a copper layer 10, a layer of nickel 11, a layer of gold or palladium 12 and finally a layer of ruthenium 13.
• FIGS. 4a to 4k schematically illustrate various steps of a method according to the invention for the manufacture of the connector 3. These steps comprise:
• This last step is advantageously carried out by masking the rear face 18 (that is to say the face intended not to be visible on the finished product).
• a mask is applied to the face of the electric circuit opposite to that receiving the conductive tracks.
• a protective film or flatten a masking belt on this face during the ruthenium deposition step.
• the ruthenium layer 13 is deposited by (electrochemistry). It is between 5 nanometers and 3 micrometers. This thickness and the deposition conditions allow to obtain a more or less dark deposit ranging from gray tones to black with increasing thickness.
• the ruthenium solution is for example a solution marketed by
• the deposition is carried out at a temperature of 65 ° C. +/- 10 ° C. with a solution containing 10 +/- 7 g / l of ruthenium and a pH of between 0.1 and 1.
• This solution advantageously comprises a blackening agent such as than thiourea.
• the ruthenium layer then comprises sulfur.
• the concentration of the blackening agent in the bath makes it possible to vary the intensity of the black color.
• the concentration of the blackening agent is 0.1 g / liter.
• the metallization rate is adjusted according to the number of metallization electrolytic cells used to achieve the desired ruthenium thickness.
• the number (for example 4) and the length of the cells are such that the substrate is treated for 2 minutes in the ruthenium solution.
• the current density conditions are also adjusted according to the surfaces to be treated and the desired thicknesses. For example, a current density of about 3 amps per square decimeter may be used.
• the ruthenium layer obtained with the process according to the invention has a good corrosion resistance satisfying the domain specifications and an electrical resistance of less than 2500 m ⁇ , or even 500 m ⁇ .
• the table below shows some examples of stacks of layers A to D that can be produced with the process according to the invention (see FIG. 5):
• the stack of ruthenium (with a thickness greater than or equal to 50 nm), on 40 to 100 nm of palladium 12, on 5 to 20 nm of gold (that is to say a "flash” of gold ), on 1 to 3 ⁇ of nickel 11 (on a copper foil 10), has an electrical resistance of less than 500m ⁇ (measured according to the ISO 10373-3 standard), a very good resistance to corrosion (especially in salt spray) and a very good adhesion of the different layers to each other.

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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)
• Credit Cards Or The Like (AREA)
• Manufacturing Of Printed Wiring (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 2012
  • 2012-10-26 FR FR1260220A patent/FR2997550B1/fr active Active
• 2013
  • 2013-10-25 BR BR112015009143A patent/BR112015009143A2/pt not_active Application Discontinuation
  • 2013-10-25 WO PCT/EP2013/072452 patent/WO2014064278A1/fr active Application Filing
  • 2013-10-25 EP EP13783552.6A patent/EP2912604A1/de not_active Withdrawn

Non-Patent Citations (2)

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