Conductive Polymer Composite for Flexible Substrate Adhesion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing conductive adhesives based on epoxy exhibit high rigidity and poor adhesion on flexible substrates, limiting their application in flexible electronic devices due to shrinkage and conductivity breakdown under external stress.
Innovation Solution
A conductive polymer composite is developed, comprising a polymer adhesive with a curable polymer and curing agent, and a conductive filler of metal and carbonaceous materials, specifically silver and multi-walled carbon nanotubes, which is formulated to provide improved adhesion, flexibility, and stretchability on flexible substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy-based conductive adhesive is used, then strong adhesion and conductivity are achieved, but rigidity increases and flexibility is lost
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive matrix from traditional epoxy to flexible polymers including silicone-based resins, urethane-based resins, acrylic resins, isoprene-based resins, chloroprene-based resins, fluorine-based resins, butadiene rubber, and styrene-butadiene rubber. This parameter change maintains adhesion strength while restoring flexibility and stretchability required for flexible electronic devices
Solution Approach 2:
The patent creates a composite material system combining flexible polymer matrices with conductive fillers (metal particles and carbonaceous materials). This composite approach achieves the dual objective of maintaining strong adhesion through the polymer matrix while incorporating conductivity through the filler particles, without sacrificing the flexibility inherent in the polymer base material
2Reliability
If epoxy-based conductive adhesive is used, then conductivity is achieved, but shrinkage phenomenon occurs under external stress
Solution Approach 1:
The patent modifies the physical and chemical parameters of the adhesive by replacing epoxy with flexible polymers that have lower shrinkage characteristics. The selected polymer materials inherently exhibit reduced shrinkage behavior while maintaining their ability to support conductive pathways under external stress and deformation
Solution Approach 2:
The flexible polymer matrix acts as an intermediary material that transmits mechanical stress uniformly throughout the adhesive layer without causing localized shrinkage. This intermediary polymer phase protects the conductive filler network from stress concentration and maintains dimensional stability during device flexing and stretching
3Reliability
If conductive filler is added to polymer adhesive, then electrical conductivity is improved, but viscosity increases
Solution Approach 1:
The patent optimizes the physical parameters of the polymer adhesive, specifically controlling viscosity within the range of 3000-5000 mPa·s before curing. This viscosity parameter is carefully selected to balance two requirements: it is low enough to allow easy mixing and dispersion of conductive fillers during manufacturing, yet high enough to provide adequate structural support and prevent filler sedimentation
Solution Approach 2:
The polymer adhesive serves as an intermediary medium that facilitates uniform dispersion of conductive fillers through its controlled viscosity characteristics. This intermediary polymer phase ensures thorough mixing during application while maintaining filler distribution stability, achieving both manufacturing ease and electrical conductivity
Data Source
AI summary
A conductive polymer composite for adhesion to a flexible substrate contains a polymer adhesive containing a curable polymer and a curing agent; and a conductive filler containing a metal and a carbonaceous material dispersed in the polymer adhesive. The conductive polymer composite is suitable for application to not only the human body but also other objects having irregular surface. In addition, due to enhanced adhesive strength of the conductive polymer composite to the flexible substrate, the reduction in conductivity or conductivity breakdown caused by external stress can be prevented and flexibility and stretchability can be improved.