Ionic Polymer Conductive Wiring Composition for Stretchable Substrates
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Solution Overview
Problem
Conductive wiring materials used in wearable devices experience a significant decrease in conductivity when stretched, due to the elongation of metal filler distances, making them less efficient and less flexible.
Innovation Solution
A conductive wiring material composition combining an ionic polymer with a metal powder, where the ionic polymer has a specific repeating unit structure and the metal powder is present in excess of 50 parts by mass, ensuring high conductivity and flexibility even during stretching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive paste with metal filler mixed with resin is used, then the wiring can be formed on substrate, but the conductivity is lowered when the printed wiring is stretched
Solution Approach 1:
The patent changes the chemical composition parameters of the conductive paste by incorporating specific ionic liquids (imidazolium, pyridinium, pyrrolidinium, or phosphonium salts with specific anions) alongside traditional metal fillers. This compositional parameter change enables the paste to maintain conductivity through ionic conduction mechanisms that are less sensitive to stretching, thereby resolving the contradiction between maintaining conductivity and enabling stretchability.
Solution Approach 2:
The patent creates a composite conductive paste material combining multiple components: metal fillers (silver, aluminum, copper, etc.), ionic liquids (various imidazolium, pyridinium, pyrrolidinium, or phosphonium salts), and resin materials. This composite structure leverages both electronic conduction from metal particles and ionic conduction from the ionic liquid, providing a material that maintains conductivity under stretching conditions while remaining processable as a paste.
2Reliability
If the wiring is made thinner to improve conductivity, then the design flexibility increases, but the wiring becomes less visible and harder to detect
Solution Approach 1:
The patent modifies the electrical conduction parameters by introducing ionic liquid components that provide alternative conduction pathways. This allows the wiring to achieve high conductivity at thinner dimensions because the ionic conduction mechanism compensates for reduced metal filler density, enabling ultra-fine wiring that maintains detectable conductivity levels despite minimal thickness.
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 composition maintains high conductivity and flexibility, allowing for efficient signal transmission and low-cost manufacturing, with the ability to form lightweight, stretchable wiring substrates suitable for wearable devices.
Implementation Method 1
The conductive wiring material composition contains (A) an ionic material and (B) metal powder... maintains high conductivity and flexibility, allowing for efficient signal transmission
Implementation Method 2
Conduction is established by the percolation phenomenon of electrons among conductive particles
Data Source
AI summary
The conductive wiring material composition includes (A) a polymer compound having a repeating unit “a” which has a structure selected from an ammonium salt, a lithium salt, a sodium salt, a potassium salt and a silver salt of any of fluorosulfonic acid, fluorosulfonimide and fluorosulfonamide and (B) metal powder, wherein the component (B) is contained with an amount exceeding 50 parts by mass based on 100 parts by mass of a solid content of the conductive wiring material composition excluding the component (B).