Silver Ink Formulation for Low-Temperature Conductive Patterns
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Solution Overview
Problem
Current methods for fabricating electrically-conductive silver patterns and films are time-consuming and expensive, particularly when using photolithographic and electroless techniques, and are not compatible with polymeric substrates, as they require high temperatures and involve sintering processes that can damage temperature-sensitive materials.
Innovation Solution
A non-aqueous precursor composition comprising a silver complex with reducible silver ions complexed with an α-oxy carboxylate and a 5- or 6-membered N-heteroaromatic compound, combined with a hydroxy-free, nitrile-containing aprotic solvent and a polymer, which can be thermally converted to form electrically-conductive silver metal at temperatures below the glass transition temperature of the silver complex.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithographic and electroless techniques are used to fabricate silver patterns, then manufacturing precision and electrical conductivity are improved, but manufacturing time and cost increase significantly
Solution Approach 1:
The silver complex is pre-formulated in the ink composition with all necessary reducing agents and stabilizers included, allowing direct printing and thermal conversion without requiring separate photolithographic exposure, development, or electroless plating steps. This preliminary preparation of the complete silver-forming system in the ink itself eliminates multiple sequential processing steps.
Solution Approach 2:
The invention extracts and eliminates the complex multi-step photolithographic and electroless plating processes from the manufacturing workflow. By incorporating silver ions, reducing agents, and stabilizers directly into a printable ink formulation, the method removes the need for separate processing baths, exposure equipment, and development steps required by conventional techniques.
2Reliability
If conventional silver ink formulations are used, then electrical conductivity can be achieved, but sintering at high temperatures damages polymeric substrates
Solution Approach 1:
The invention changes the chemical parameters of the silver-forming system by using organic reducing agents (hydrazine, hydroxylamine, formate, acetate) that enable silver reduction at low temperatures (below 150°C). The use of complexing agents (amines, carboxylic acids) modifies the reduction kinetics and allows controlled silver metal formation at temperatures compatible with polymeric substrates, achieving electrical conductivity without substrate damage.
Solution Approach 2:
The invention introduces organic reducing agents and complexing agents as intermediaries between silver ions and the final silver metal. These intermediaries facilitate gentle, controlled reduction of silver ions at low temperatures, avoiding the harsh high-temperature sintering required by conventional metal particle inks. The complexing agents mediate the reduction process by controlling the availability and reactivity of silver ions throughout the heating process.
3Productivity
If rapid thermal conversion is used to form silver metal, then productivity increases, but control over reduction process becomes difficult
Solution Approach 1:
The invention employs periodic or staged thermal conversion where the ink is heated in controlled increments or held at intermediate temperatures to allow progressive silver metal formation. This staged approach enables monitoring and adjustment of the reduction process, maintaining process control while achieving rapid overall conversion. The multi-component chemistry (complexing agents, reducing agents, stabilizers) provides multiple reaction stages that can be controlled sequentially.
Solution Approach 2:
The invention incorporates feedback mechanisms through the use of stabilizers and complexing agents that respond to the reduction progress. These agents continuously modulate the availability of silver ions for reduction, providing self-regulating feedback that prevents runaway reduction. The complexing equilibrium shifts dynamically based on silver ion concentration, automatically adjusting the reduction rate to maintain process control throughout the thermal conversion.
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
This approach allows for the rapid and cost-effective generation of electrically-conductive silver metal patterns on a wide range of substrates, including polymeric materials, with high conductivity and stability, reducing the need for high-temperature sintering and improving manufacturing efficiency.
Implementation Method 1
thermally converted to form electrically-conductive silver metal at temperatures below the glass transition temperature of the silver complex
Data Source
AI summary
Electrically-conductive silver metal is provided in a pattern on a substrate having a first supporting side and a second opposing supporting side. One or both of the first supporting side and the second opposing supporting side has one or more electrically-conductive silver metal containing patterns containing the electrically-conductive silver metal; an α-oxy carboxylate; a 5- or 6-membered N-heteroaromatic compound; and a polymer that is either (i) a hydroxy-containing cellulosic polymer or (ii) a non-cellulosic acrylic polymer having a halo- or hydroxy-containing side chain. Such articles can be used in various devices and electrodes.