Stretchable Conductive Interconnect Paste for Crack-Free Flexing
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Solution Overview
Problem
Conventional conductive pastes are not suitable for forming flexible conductive layers or interconnections that can be stretched without cracking or losing electrical continuity, and they lack adequate resistance to environmental factors and temperature extremes, making them unsuitable for applications like capacitive touch technologies and flexible electronics.
Innovation Solution
A conductive paste comprising conductive particles dispersed in an organic medium with a solvent and a binder, specifically a polyester, which allows for the formation of a conductive coating or interconnection that can be stretched up to 150% without substantial crack formation or loss in electrical continuity, and can be cured at low temperatures, making it suitable for flexible substrates and various applications including capacitive touch technologies and stretchable electronic surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional conductive paste is used, then electrical conductivity is achieved, but the paste cracks and loses electrical continuity when stretched
Solution Approach 1:
The patent changes the chemical composition parameters of the conductive paste by incorporating specific polymers (polyurethane, polyester, or epoxy resin) as binders and using metal particles (silver, copper, aluminum, or their alloys) with controlled size distributions. This compositional parameter change enables the paste to maintain both electrical conductivity and mechanical flexibility, allowing it to stretch without cracking and preserving electrical continuity under deformation.
Solution Approach 2:
The patent creates a composite conductive paste material combining metal particles (conductive phase) with polymer binders (structural phase) in specific ratios. This composite structure provides both electrical conductivity from the metal network and mechanical flexibility from the polymer matrix, resolving the contradiction between maintaining electrical continuity and achieving mechanical flexibility during stretching.
2Reliability
If conventional conductive paste is used, then conductivity is achieved, but the paste forms gel or cracks after long storage or stretching
Solution Approach 1:
The patent optimizes the chemical composition parameters including metal particle size distribution (0.5-50 micrometers), binder type selection, and solvent composition to prevent gel formation during storage. These parameter changes ensure the paste remains stable and printable while maintaining its ability to form crack-free, electrically continuous conductors after stretching and curing.
3Reliability
If conventional conductive paste is used, then conductive layer is formed, but high temperature sintering damages the substrate
Solution Approach 1:
The patent changes the curing temperature parameter from conventional high-temperature sintering (above 200°C) to low-temperature curing (50-150°C). This is achieved through the selection of polymer binders with appropriate glass transition temperatures and the use of controlled atmosphere curing processes, enabling the formation of electrically continuous conductive layers without damaging temperature-sensitive substrates.
4Reliability
If conventional conductive paste is used, then conductive interconnection is formed, but the paste lacks resistance to environmental effects
Solution Approach 1:
The patent develops a composite paste formulation combining metal particles with specifically selected polymer binders (polyurethane, polyester, or epoxy resin) that provide inherent environmental resistance. This composite structure protects the conductive metal network from oxidation and environmental degradation while maintaining printability and electrical performance, achieving environmental resistance through material composition rather than additional protective layers.
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 conductive paste achieves excellent adhesion, mechanical robustness, and electronic performance, enabling applications such as stretchable electronics, LED lighting, and wearable devices with integrated thermal and electrical interconnects, while maintaining conductivity and flexibility even after stretching or bending.
Implementation Method 1
The conductive paste can be cured at low temperatures
Data Source
AI summary
A conductive paste and method of manufacturing thereof. The conductive paste comprises conductive particles dispersed in an organic medium, the organic medium comprising: (a) a solvent; and (b) a binder comprising a polyester. The conductive paste typically comprises silver and may contain various other additives. A stretchable conductive layer can be formed by curing the conductive paste.