Conductive Ink Composition for Flexible Electronics
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Solution Overview
Problem
Conductive inks fail to remain conductive and adhere to substrates when bent or creased, limiting their flexibility and application in flexible electronics, such as printed circuitry on carton-board that needs to be folded.
Innovation Solution
A conductive ink composition comprising thermoplastic polyurethane (TPU) with an elongation at break ranging from 200% to 1500% at 23°C, combined with silver particles and a diluent liquid, which provides excellent adhesion and retains conductivity even after multiple flexing cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional conductive inks are used on flexible substrates, then the ink can be printed and initially conductive, but the conductivity is lost when the substrate is bent or creased
Solution Approach 1:
The patent changes the physical and chemical parameters of the binder material by selecting thermoplastic polyurethane with specific elongation properties (200-1500% at break) and specific gravity (0.9-1.2 g/cm³). This parameter optimization allows the ink formulation to maintain conductivity through flexible substrate deformation while preserving adhesion, directly resolving the contradiction between reliability and adaptability
Solution Approach 2:
The patent creates a composite conductive ink system combining thermoplastic polyurethane binder, silver particles (5-20 microns), and diluent liquid. This composite formulation leverages the flexibility and adhesion of TPU combined with the conductivity of silver particles, enabling the ink to maintain both mechanical flexibility and electrical conductivity when the substrate is bent or creased
2Reliability
If conventional conductive inks are used on flexible substrates, then the ink can be printed and initially adherent, but the adhesion fails when the substrate is bent or creased
Solution Approach 1:
The patent optimizes the binder parameters including elongation at break (200-1500%) and specific gravity (0.9-1.2 g/cm³) to match the substrate properties. This parameter matching enables the ink to accommodate substrate flexibility while maintaining strong adhesion, preventing delamination during bending and creasing operations
Solution Approach 2:
The thermoplastic polyurethane binder forms a flexible film matrix that can deform with the substrate without breaking adhesion bonds. This flexible film structure allows the conductive ink to maintain both adhesion and flexibility, resolving the contradiction between reliable adhesion and substrate adaptability
3Adaptability or versatility
If highly flexible polymer binders are used to maintain conductivity after bending, then the ink becomes flexible, but the adhesion to substrate deteriorates
Solution Approach 1:
The patent carefully balances the binder parameters by selecting thermoplastic polyurethane with elongation at break between 200-1500% and specific gravity of 0.9-1.2 g/cm³. This optimized parameter range provides sufficient flexibility for substrate deformation while maintaining adequate adhesion strength, preventing the trade-off between flexibility and adhesion
Solution Approach 2:
The patent ensures homogeneous distribution of silver particles (5-20 microns) within the thermoplastic polyurethane binder matrix. This homogeneous formulation ensures uniform mechanical properties and adhesion across the ink layer, allowing the flexible substrate to deform uniformly without creating weak points that would compromise adhesion
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 ink composition maintains conductivity and adhesion across creases and multiple flexing cycles, demonstrating superior performance compared to traditional inks, with a flexible and air-stable solution suitable for low-temperature processing and use in flexible electronics.
Implementation Method 1
The thermoplastic polyurethane has the property of exhibiting an elongation at break ranging from about 200% to about 1500% at 23° C. when in pure polymer form
Data Source
AI summary
An ink composition comprises a thermoplastic polyurethane; particles comprising silver; and at least one diluent liquid. The thermoplastic polyurethane has the property of exhibiting an elongation at break ranging from about 200% to about 1500% at 23° C. when in pure polymer form.