Printed Electronics Using Flake-less Molecular Inks
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Solution Overview
Problem
Current silver flake inks face challenges in producing flexible, thin, and conductive traces with high adhesion and resolution due to their large flake size, leading to issues with mechanical robustness, adhesion limitations, and rough surfaces, which are problematic for applications like RFID and RF filtering.
Innovation Solution
Development of flake-less molecular inks comprising 30-60 wt % of C8-C12 silver carboxylate or 5-75 wt % of copper formate compounds, combined with a polymeric binder and organic solvent, which form conductive metal nanoparticles upon processing, resulting in thinner, more conductive, and more adhesive traces with improved print resolution and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver flake inks are used to form conductive traces, then electrical conductivity is achieved, but the traces exhibit rough surfaces and poor adhesion due to large flake size
Solution Approach 1:
The invention changes the physical state and size parameter of the conductive material from large metal flakes to molecular-scale precursors (silver carboxylates with 8-12 carbon atoms). This parameter change enables the formation of smooth, thin traces with superior adhesion while maintaining electrical conductivity, directly resolving the contradiction between adhesion reliability and surface precision.
Solution Approach 2:
The invention applies local quality by creating uniform molecular distributions throughout the ink composition, ensuring consistent trace properties at the micro-scale. The molecular precursors distribute more evenly than flake inks, producing homogeneous traces with improved adhesion and reduced surface roughness locally across the entire printed area.
2Strength
If silver flake inks are used, then conductive traces are formed, but mechanical robustness and flexibility are limited due to flake structure
Solution Approach 1:
The invention transforms the structural parameter of the conductive material from discrete flake particles to continuous molecular chains that can flex and deform. This parameter change enables the traces to bend, stretch, and conform to flexible substrates while maintaining mechanical robustness and electrical conductivity, resolving the contradiction between strength and adaptability.
3Reliability
If molecular inks with lower resistivity are used, then electrical performance improves, but print resolution and trace thickness control become more challenging
Solution Approach 1:
The invention replaces the mechanical flake-based deposition system with a molecular-level deposition system. The molecular precursors (silver carboxylates) decompose and sinter at controlled temperatures to form conductive traces, allowing precise control of trace thickness through thermal processing parameters rather than mechanical flake size, thus achieving both high conductivity and precise thickness control.
4Manufacturing precision
If flake-less molecular inks are used, then surface roughness decreases significantly, but the complexity of ink composition formulation increases
Solution Approach 1:
The invention uses composite material formulation by combining silver carboxylate molecules with specific binder polymers and solvents in optimized ratios. This composite approach simplifies the overall ink system while achieving the desired molecular uniformity and printability, balancing surface precision requirements with formulation complexity through synergistic material combinations.
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 molecular inks produce traces with lower resistivity, enhanced adhesion, and up to 8 times less roughness compared to metal flake inks, enabling the creation of flexible and high-resolution electronic devices, including RF antennas and filters, with improved durability and performance.
Implementation Method 1
the molecular ink being sintered to form a conductive metal trace
Data Source
AI summary
The present invention relates to an electronic device comprising a printed substrate comprising a trace of molecular ink thereon, the molecular ink being sintered to form a conductive metal trace forming the electronic device, wherein the molecular ink is chosen from a) a flake-less printable composition of 30-60 wt % of a C8-C12 silver carboxylate, 0.1-10 wt % of a polymeric binder and balance of at least one organic solvent, all weights based on total weight of the composition; or b) a flake-less printable composition of 5-75 wt % of bis(2-ethyl-1-hexylamine) copper (II) formate, bis(octylamine) copper (II) formate or tris(octylamine) copper (II) formate, 0.25-10 wt % of a polymeric binder and balance of at least one organic solvent, all weights based on total weight of the composition.