Flexible RFID Tag Inlay Design for Stress Resistance

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Solution Overview

Problem

Existing flexible RFID tags lack sufficient mechanical stress resistance, particularly in harsh environments like laundry or industrial processes, due to inadequate protection and handling issues during manufacturing, leading to potential cracking and breaking when bent or compressed.

Innovation Solution

A flexible RFID tag design featuring a flexible substrate layer with an antenna and chip, covered by a second flexible layer forming a protective inlay, embedded in a flexible housing with optional rigid protection rings, where the chip and antenna are only mechanically connected to the substrate, allowing for deformation without direct stress from the housing materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the chip and antenna are fixed directly to the housing structure, then mechanical strength and positioning stability are improved, but flexibility and resistance to bending stress deteriorate

Engineering Contradiction:
Improvemechanical strengthVSAvoidflexibility
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The housing is divided into a rigid outer housing and a separate protective inlay. The inlay is further segmented into a first flexible layer supporting the chip and antenna, and a second flexible layer covering them. This segmentation allows the rigid housing to provide overall strength while the flexible inlay layers provide bending resistance and protect the electronic components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The protective inlay acts as an intermediary between the rigid housing and the chip/antenna. It mediates the mechanical stresses by absorbing and distributing bending forces, preventing direct transmission of stress to the electronic components while maintaining their fixed positions.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If soft adhesive material is used to hold the chip and antenna, then flexibility is improved, but manufacturing complexity and cost increase

Engineering Contradiction:
ImproveflexibilityVSAvoidmanufacturing complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The protective inlay uses flexible layers (first and second flexible layers) made of materials like polyimide or flexible PCB material. These thin flexible films provide the necessary flexibility and protection without requiring soft adhesive materials, simplifying the manufacturing process while maintaining component flexibility.

Inventive Principle:
Principle #30Flexible shells and thin films

3Adaptability or versatility

If the chip and antenna are freely floating without support structure, then flexibility is improved, but mechanical impact resistance deteriorates

Engineering Contradiction:
ImproveflexibilityVSAvoidmechanical impact resistance
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The housing structure is segmented into a rigid outer housing providing impact resistance and a separate protective inlay with flexible layers supporting the chip and antenna. This segmentation allows the rigid housing to absorb mechanical impacts while the flexible inlay maintains component flexibility and positioning.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The protective inlay combines different flexible materials (first and second flexible layers) with complementary properties. The first layer provides support and electrical connection, while the second layer provides additional protection and flexibility, creating a composite structure that resists both bending and impact.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP2657889B1Flexible tag
Publication Date: 2020.05.06 ASSA ABLOY AB
  • EP2657889B1 patent drawingFigure 1~2
  • EP2657889B1 patent drawingFigure 3~4

AI summary

A flexible Radio-Frequency IDentification (RFID) tag comprises a flexible substrate layer (4) on which is fixed an antenna (7) connected to a RFID chip (5), and a second flexible layer (6) placed directly over the said chip and antenna but without any direct mechanical connection to them, such that the substrate layer (4) and the second layer (6) form a protective inlay (3) for the chip (5) and the antenna (7). The said inlay is embedded in a flexible housing (1).