Multicolored Smart Card Circuits Using Laser-Revealed Dielectric Layers

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Solution Overview

Problem

Existing smart card modules lack the ability to create complex and secure color patterns that are resistant to falsification, as they primarily rely on visible colors and lack advanced security features.

Innovation Solution

Incorporating a process that uses a laser beam to engrave and reveal underlying colors of dielectric layers, potentially with photochromic or thermochromic agents, to create secure and complex color patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional manufacturing processes are used with visible colors, then the manufacturing process is simple, but the security against falsification is insufficient

Engineering Contradiction:
Improvesecurity against falsificationVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies photochromic and thermochromic agents that change color under specific conditions (UV light exposure or temperature changes). This creates security patterns that are not visible under normal conditions but reveal themselves under specific triggers, providing anti-falsification capability while maintaining a relatively simple manufacturing process by incorporating these agents into the dielectric layers during conventional lamination steps.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The patent uses composite dielectric layers containing photochromic and thermochromic agents mixed with adhesive materials. These composite materials combine the functional properties of adhesives with the security properties of chromic agents, allowing security features to be integrated into the structural layers of the printed circuit board without requiring separate security element fabrication steps.

Inventive Principle:
Principle #40Composite materials

2Adaptability or versatility

If multiple dielectric layers of different colors are stacked, then complex color patterns can be created, but the manufacturing process becomes more complex

Engineering Contradiction:
Improvecolor pattern complexityVSAvoidnumber of dielectric layers
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the color pattern creation into multiple dielectric layers, each containing different chromic agents or color combinations. By stacking these layers and selectively exposing or heating specific regions, complex multi-colored security patterns are achieved. The segmentation allows independent control of different color layers, enabling versatile pattern design while managing manufacturing complexity through systematic layer-by-layer processing.

Inventive Principle:
Principle #1Segmentation

3Reliability

If laser beam engraving is used to reveal underlying colors, then security patterns are enhanced, but the manufacturing process requires additional equipment

Engineering Contradiction:
Improvesecurity pattern authenticityVSAvoidmanufacturing equipment complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent incorporates photochromic and thermochromic agents into the dielectric layers during the initial material preparation stage, before the actual security pattern formation. This preliminary action ensures that the security-reactive materials are already in place and properly distributed throughout the layers, so that subsequent laser engraving or UV exposure steps can directly activate the pre-positioned agents without requiring additional material application or complex real-time processing equipment.

Inventive Principle:
Principle #10Preliminary action

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

Engraving with a laser beam allows for the creation of secure, multi-colored patterns that are difficult to falsify, enhancing security and providing complex, flexible and secure color patterns that are resistant to falsification.

Implementation Method 1

engraving, on a portion of the area left visible of the assembly comprising at least two layers of dielectric material of different colors, at least one of the two layers of different colors, using a laser beam

Methodology Applied
Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

The colors may originate from photochromic agents sensitive to light with wavelengths in the ultraviolet or infrared range

Methodology Applied
Scientific EffectPhotochromism: Photochromism

Implementation Method 3

The colors may originate from heat-sensitive thermochromic agents

Methodology Applied
Scientific EffectThermochromism: Thermochromism

Data Source

PatentEP4371032B1Method for manufacturing multicoloured printed circuits for smart card modules
Publication Date: 2025.12.31 LINXENS HOLDING SAS
  • EP4371032B1 patent drawingFigure 1
  • EP4371032B1 patent drawingFigure 2a~2l
  • EP4371032B1 patent drawingFigure 3a~4b

AI summary

A method for manufacturing flexible printed circuits for smart card modules, wherein a complex material is provided. Said complex material comprises a set of at least two different-coloured strata. Areas (64, 65, 66, 67) of said set are visible through the layer of electrically conductive material (60). Said manufacturing method comprises a step of etching, on a portion of the exposed area (64, 65, 66, 67) of the strata set, at least one of the two different-coloured strata, using a laser beam, so as to render visible the other of the two different-coloured strata. A printed circuit manufactured by said method. A module and a smart card comprising said printed circuit.