Thermoformable Conductive Member for Crack-Resistant Electrical Continuity

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing methods for forming electrically conductive tracks on flexible substrates are costly and result in poor electrical conductivity and continuity issues after thermoforming, particularly due to the formation of breaks or cracks during deformation.

Innovation Solution

A thermoformable device comprising a substrate with an electrically conductive member made of conductive particles, conductive material, and elongated elements with specific melting temperatures, where the conductive material melts during thermoforming to connect the particles and elongated elements, ensuring electrical continuity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional conductive inks with polymer and particles are used, then cost is reduced and flexibility is enabled, but electrical conductivity deteriorates and continuity is lost after thermoforming

Engineering Contradiction:
Improvecost reductionVSAvoidelectrical conductivity
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The invention uses a composite conductive ink formulation containing metal particles (silver, copper, or aluminum), polymer binder, and plasticizer. This composite structure allows the ink to maintain flexibility while providing adequate electrical conductivity even after thermoforming, resolving the contradiction between ease of manufacture and reliability

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention modifies the physical and chemical parameters of the conductive ink by adjusting particle size distribution (0.5-10 μm), polymer type and content (5-20 wt%), and plasticizer content (2-10 wt%). These parameter changes enable the ink to maintain electrical continuity during substrate deformation while keeping manufacturing costs low

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If conductive tracks are formed on flexible substrates, then adaptability to complex shapes is improved, but electrical continuity deteriorates due to breaks and cracks during deformation

Engineering Contradiction:
Improveshape adaptabilityVSAvoidelectrical continuity
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The invention forms conductive tracks as thin film structures on flexible substrates using screen printing or inkjet deposition. The thin film nature (micrometer scale) allows the conductive layer to stretch and deform with the substrate without developing cracks, maintaining electrical continuity while adapting to complex three-dimensional shapes

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The polymer binder acts as an intermediary between the rigid metal particles and the flexible substrate. It provides a compliant matrix that allows particle movement and redistribution during deformation, preventing track breaks and maintaining electrical continuity while enabling shape adaptability

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If rigid support structures are used for conductive tracks, then electrical conductivity is maintained, but flexibility and thermoformability are lost

Engineering Contradiction:
Improveelectrical conductivityVSAvoidflexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention creates local conductive pathways through the distribution of metal particles within the polymer matrix. Rather than requiring a continuous rigid structure, localized particle clusters provide conductivity at critical points while the polymer matrix provides overall flexibility, enabling both electrical reliability and adaptability

Inventive Principle:
Principle #3Local quality

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 solution maintains satisfactory electrical conductivity and continuity of the conductive member even after deformation, allowing for reliable electrical connections in thermoformed devices.

Implementation Method 1

the electrically conductive material has a melting temperature strictly lower than the melting temperature of the electrically conductive particles and the melting temperature of the elongated elements

Methodology Applied
Scientific EffectMelting: Melting

Data Source

PatentEP3349548B1Device comprising a substrate capable of being thermoformed, on which an electrically conductive member is arranged
Publication Date: 2025.09.10 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
  • EP3349548B1 patent drawingFigure 1~4
  • EP3349548B1 patent drawingFigure 5~8
  • EP3349548B1 patent drawingFigure 9~11

AI summary

The device (1) intended to be thermoformed comprises a substrate (3) capable of being thermoformed and an electrically conductive member (2) integral with said substrate (3). The electrically conductive member (2) comprises: electrically conductive particles (4), an electrically conductive material (5), electrically conductive elongated elements (6). The electrically conductive material (5) has a melting temperature strictly lower than the melting temperature of the electrically conductive particles (4) and the melting temperature of the elongated elements (6).