Colored Chip Card Contacts With Black Conductive Surface Coatings
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Solution Overview
Problem
Existing methods for producing colored contacts or conductive tracks in smart cards and similar electrical circuits cannot achieve a black or close to black color while maintaining necessary electrical and mechanical properties.
Innovation Solution
A method involving physical vapor deposition of specific metals like chromium, hafnium, and tantalum in an atmosphere with argon and oxygen to form a surface layer with a compound of the type XpOqNrCs, which provides a dark or black color, high conductivity, and robustness, along with optional bonding layers and laser engraving for de-short-circuiting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional coating methods (gold, silver, palladium) are used to obtain colored contacts, then aesthetic value and color variety are improved, but the ability to achieve black or close-to-black color is lost
Solution Approach 1:
The invention changes the chemical composition parameters of the coating material by using a compound with formula XpOqNrCs containing transition metals (Cr, Hf, Ta, Zr, Nb, Mo, V, Ti, or Sc) combined with oxygen, nitrogen, and carbon. This parameter change in composition enables the achievement of black color while maintaining electrical conductivity, resolving the limitation of traditional noble metal coatings that cannot produce black color.
Solution Approach 2:
The invention employs composite materials by creating a compound layer that combines transition metal elements with oxygen, nitrogen, and carbon in specific ratios. This composite structure provides both the desired black color and the necessary electrical conductivity, overcoming the limitation of single-material coatings like gold or silver that cannot simultaneously achieve black color and conductive properties.
2Illumination intensity
If a dark or black colored surface layer is applied to conductive tracks, then aesthetic value is improved, but electrical conductivity may deteriorate
Solution Approach 1:
The invention uses composite materials by formulating a compound layer with transition metals (X) combined with oxygen (O), nitrogen (N), and carbon (C) in controlled proportions. This composite structure allows the material to exhibit both black color and adequate electrical conductivity, resolving the contradiction between aesthetic appearance and electrical functionality.
Solution Approach 2:
The invention optimizes the stoichiometric parameters p, q, r, and s in the compound formula XpOqNrCs to achieve the right balance between color intensity and electrical conductivity. By carefully controlling the ratios of metal to oxygen, nitrogen, and carbon, the coating achieves black color while maintaining sufficient conductive properties for smart card applications.
3Strength
If a thick surface layer is deposited to ensure robustness and corrosion resistance, then mechanical strength is improved, but manufacturing complexity increases
Solution Approach 1:
The invention optimizes the thickness parameter of the surface layer to achieve the minimum required robustness and corrosion resistance. By carefully controlling the deposition thickness and composition ratios, the process achieves adequate protection without requiring excessively thick layers that would increase manufacturing complexity and cost.
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 close to black color that meet the electrical and mechanical requirements for smart cards, including low contact resistance and resistance to salt spray corrosion, while allowing for other color options.
Implementation Method 1
the formation of the surface layer comprises a step of physical vapor deposition from at least one metal target
Implementation Method 2
in an atmosphere comprising at least one of the following elements: argon, nitrogen and oxygen
Data Source
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AI summary
The invention relates to an electric circuit, for example of the printed circuit type, for producing a module intended to be integrated into a chip card. This module comprises electric contact pads - or connectors (3) - allowing the chip to be connected to, and to communicate with, a read/write system. In order to give them a colour different from the gold and silver colours generally used, these electric contact pads (3) are at least partially covered with a surface layer (14) comprising a compound of the XpOqNrCs type, wherein X can be Hf, Ta, Zr, Nb, Mo, Cr, V, Ti or Sc, wherein p, q > 0 and r ≥ 0 and/or s ≥ 0. The invention also relates to a method for producing such an electric circuit.