Chip Card Contact Circuit Coating for Black Conductive Contacts
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Solution Overview
Problem
Existing methods for producing colored contacts or conductive tracks on chip cards, such as those used in SD memory cards and USB sticks, cannot achieve a black or near-black color while maintaining necessary electrical and mechanical properties for chip card applications.
Innovation Solution
A method involving physical vapor deposition of a surface layer composed of metals like chromium, hafnium, tantalum, and titanium in an atmosphere with argon, nitrogen, and oxygen, forming a compound with specific stoichiometry to achieve a dark, conductive, and robust coating for chip card modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional gold, silver, or palladium plating methods are used to color contacts, then aesthetic appearance is improved, but the ability to achieve black or near-black color is lost
Solution Approach 1:
The patent changes the fundamental parameter of the coating material from traditional precious metals (gold, silver, palladium) to transition metals (chromium, hafnium, tantalum, zirconium, niobium, molybdenum, vanadium, titanium, scandium) and their compounds. This parameter change enables the achievement of black and near-black colors that were previously unattainable with traditional plating methods, while maintaining electrical conductivity and mechanical properties.
2Illumination intensity
If colored coatings are applied to contacts, then aesthetic value is improved, but electrical conductivity may be compromised
Solution Approach 1:
The patent employs composite material structures consisting of multiple layers: a base conductive layer (copper, aluminum, or their alloys) provides electrical conductivity, while subsequent layers of transition metals and their compounds (such as chromium oxide, titanium nitride, or other stoichiometric compounds) provide coloration. This composite structure ensures that the colored surface layer does not compromise the electrical conductivity of the underlying conductive material, achieving both aesthetic value and functional reliability.
3Illumination intensity
If transition metal compounds are deposited via physical vapor deposition, then black color and electrical conductivity are achieved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces traditional electrochemical deposition methods with physical vapor deposition (PVD) techniques to deposit transition metal compounds. This substitution enables precise control over film thickness, composition, and stoichiometry, achieving the desired black color and electrical conductivity properties. The PVD process allows for better control of deposition parameters and produces more uniform coatings compared to conventional methods, despite the increased equipment complexity.
4Reliability
If multiple deposition layers are used to achieve desired color and properties, then product performance is improved, but production time increases
Solution Approach 1:
The patent applies different material compositions and thicknesses to different functional regions of the contact surface. The base layer provides mechanical robustness and structural integrity, while thinner surface layers of transition metal compounds provide coloration and electrical conductivity. By optimizing the local thickness and composition of each layer, the patent achieves the required performance properties while minimizing the total number of deposition steps and reducing manufacturing cycle time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method successfully produces conductive tracks with a black or near-black color that maintains electrical conductivity and mechanical robustness, suitable for chip card applications, including banking standards, while allowing for other color options.
Implementation Method 1
depositing at least one layer of an electrically conductive material on the sheet of electrically conductive material, this layer of an electrically conductive material forming a surface layer covering at least one region of the surface of at least one conductive track... the formation of the surface layer includes a step of physical vapour deposition from at least one metal target
Data Source
AI summary
The invention relates to an electrical circuit, for example of the printed circuit type, for producing a module intended to be integrated into a chip card. This module has electrical contact—or connector—areas for the connection and communication of the chip to and with a read/write system. In order to give them a different colour from the gilded or silvered ones generally used, these electrical contact areas are at least partially covered with a surface layer comprising a compound of XpOqNrCs type, in which X may be Hf, Ta, Zr, Nb, Mo, Cr, V, Ti or Sc, with p, q>0 and r≥0 and/or s≥0. The invention also relates to a method for manufacturing such an electrical circuit.