Smart Card Antenna Design for Dual Interface Compatibility
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Solution Overview
Problem
The reduction in size of dual interface communication modules for smart cards, such as the 'DUAL 6' type, results in reduced antenna impedance and resonance frequency, making them incompatible with existing contactless readers, and the production of metallized vias increases costs.
Innovation Solution
The design increases the space for antenna turns by expanding the triangle between connection wells and transferring the distal end of the antenna to the module's encapsulation zone, allowing for additional turns and higher inductance while maintaining track sizes and distances, and incorporating proximal connection pads for fine-tuned impedance adaptation to chip capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of dual interface communication modules is reduced to meet market demand for smaller smart cards, then the module dimensions decrease, but the antenna impedance and resonance frequency are reduced making the cards incompatible with existing contactless readers
Solution Approach 1:
The antenna turns are nested within the triangle formed by the connection wells of contacts C1, C5 and the distal terminal, maximizing the use of available space. The antenna is positioned to pass through this triangular region, allowing sufficient turns to be accommodated within the reduced module footprint while maintaining the required inductance for compatibility with existing readers
Solution Approach 2:
The design utilizes the vertical dimension by extending the antenna turns through the thickness of the module substrate. The antenna passes through connection wells that extend vertically, allowing the antenna to gain additional effective length in the Z-direction, thereby increasing inductance without increasing the planar footprint of the module
2Reliability
If metallized vias are produced to connect chip terminals to contacts and antenna, then electrical connection is achieved, but production costs increase
Solution Approach 1:
The design extracts the antenna connection terminals and places them inside the encapsulation zone of the chip, where they can be directly connected to chip terminals through the substrate without requiring separate metallized vias. This integration eliminates the need for additional via fabrication steps and reduces manufacturing complexity
Solution Approach 2:
The antenna connection path is merged with the existing substrate structure and connection well architecture. The antenna tracks are routed to share the same connection wells and substrate pathways already designed for contact connections, consolidating multiple functions into a single integrated structure that avoids additional manufacturing processes
3Adaptability or versatility
If the number of antenna turns is increased to maintain resonance frequency in smaller modules, then inductance increases, but the available space for antenna placement decreases
Solution Approach 1:
The connection wells for contacts C1 and C5 are given increased spacing and optimized geometry specifically in the region where the antenna turns pass through. This localized optimization of the connection well area creates sufficient room for the antenna to make multiple turns without interfering with the electrical connections, allowing high inductance within limited space
Solution Approach 2:
The antenna design allows for flexible routing of turns that can dynamically adapt to the available space within the triangle. The antenna path is not fixed but can be configured to maximize turns within the triangular boundary, optimizing inductance based on the specific module dimensions and connection well locations
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 enables a larger antenna on smaller modules, ensuring compatibility with existing readers and allowing resonance frequency adjustment to match various chip capacitances without the need for metallized vias, thus enhancing manufacturing efficiency and performance.
Implementation Method 1
having on the other hand a radio frequency communication interface provided with at least an antenna and able to communicate with the antenna of a contactless reader
Implementation Method 2
the increase in the resonance frequency f of the module, equal to 1/(2π√LC)
Data Source
AI summary
An electronic module for a smart card has on a first face a terminal block of electrical contacts for contact with corresponding contacts of a card reader, and on a second face an antenna and a microelectronic chip within an encapsulation zone and provided with contact and contactless communication interfaces. The antenna has a plurality of turns at the periphery of the module and a proximal connection pad and a distal connection pad inside the encapsulation zone for connection to corresponding terminals of the contactless communication interface. The distal connection pad is located a short distance d from the edge of the encapsulation zone, and the internal edges of connection wells of the two contacts closest to the distal connection pad are spaced outward from the module relative to the internal edges of the connection wells of the other contacts.