RFID Card Antenna Integration for Resonant Frequency Adjustment

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Solution Overview

Problem

The production of small-sized RFID cards with integrated capacitors to adjust resonant frequency faces challenges due to the incompatibility of discrete surface-mounted components with wire-frame manufacturing techniques and the high complexity and cost of PCB-based manufacturing, limiting design flexibility and aesthetic customization.

Innovation Solution

The integration of a wire-type RF antenna within a plastic substrate, using a wire-frame fabrication technique, which allows for the inclusion of a discrete capacitor in the electronic module to adjust the resonant frequency without requiring a PCB, enabling simpler construction, reduced costs, and aesthetic customization through lamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a discrete surface-mounted capacitor is added to adjust resonant frequency in small RFID cards, then the resonant frequency can be adjusted, but the wire-frame manufacturing technique becomes incompatible

Engineering Contradiction:
Improveresonant frequency adjustmentVSAvoidmanufacturing technique compatibility
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent combines the capacitor and RF microcontroller into a single integrated circuit package, eliminating the need for separate surface-mounted capacitor components. This integration allows the use of wire-frame manufacturing techniques while maintaining the ability to adjust resonant frequency through the integrated circuit design.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The capacitor is nested within the electronic module housing along with the RF microcontroller. This nesting approach allows the capacitor to be positioned in a way that is compatible with wire-frame antenna manufacturing, as the entire electronic module is treated as a single unit rather than requiring separate component mounting on the card surface.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Manufacturing precision

If PCB-based manufacturing is used to accommodate discrete capacitors, then the resonant frequency can be adjusted, but the construction complexity and manufacturing cost increase

Engineering Contradiction:
Improveresonant frequency adjustmentVSAvoidconstruction complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges the capacitor, RF microcontroller, and their interconnections into a single integrated circuit package. This eliminates the need for complex PCB routing and assembly, reducing construction complexity while maintaining the ability to adjust resonant frequency through the integrated circuit's internal design.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts the electronic components (capacitor and microcontroller) from the traditional PCB-based assembly and places them directly into a simplified electronic module housing. This extraction eliminates the need for complex PCB manufacturing processes while maintaining electrical connectivity and resonant frequency adjustment capabilities.

Inventive Principle:
Principle #2Taking out (Extraction)

3Manufacturing precision

If PCB-based manufacturing is used, then discrete capacitors can be mounted, but aesthetic customization through lamination becomes impossible

Engineering Contradiction:
Improveresonant frequency adjustmentVSAvoidaesthetic customization
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

By combining all electronic components into a single integrated circuit package housed within a compact module, the patent creates a streamlined structure that can be easily laminated. This merged design removes the need for complex PCB assemblies that would interfere with lamination processes, enabling aesthetic customization while maintaining resonant frequency adjustment capabilities.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent uses a compact electronic module housing that can be effectively laminated with thin protective or aesthetic films. This approach allows for aesthetic customization through lamination while the integrated circuit inside maintains the resonant frequency adjustment functionality, unlike rigid PCB-based constructions.

Inventive Principle:
Principle #30Flexible shells and thin films

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

This approach allows for the production of small-sized RFID cards with adjusted resonant frequencies using wire-frame techniques, reducing manufacturing complexity and costs, while enabling aesthetic customization and improved reliability by eliminating the need for PCBs.

Implementation Method 1

The RF microcontroller 84 operates in a contactless mode using the energy collected by the RF antenna 86 from RF signals coming from a contactless reader

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

an additional capacitor ΔC is connected in parallel across the terminals of the RF microcontroller 92 in order to be able to adjust the working frequency of the RF antenna 90

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP3574451B1RFID device and method for manufacturing same
Publication Date: 2021.03.03 IDEMIA FRANCE SAS
  • EP3574451B1 patent drawingFigure 1~2
  • EP3574451B1 patent drawingFigure 3~4
  • EP3574451B1 patent drawingFigure 5~6

AI summary

The invention relates to an RFID card (2) comprising a substrate (5); a radiofrequency (RF) wire antenna (12) formed in the substrate (5); and an electronic module (4) disposed in the substrate (5) and comprising: an RF chip (3), a capacitor (CP) in the form of a discrete component external to the RF chip (3), and a housing (14) wherein the RF chip (3) and the capacitor (CP) are encapsulated; both the RF chip (3) and the capacitor (CP) being electrically connected in parallel at two ends (12A, 12B) of the RF antenna (12) so that the electronic module (4) can communicate in a non-contact mode with the outside of the card (2) using said RF antenna (12).