Copper Precursor Films for Flexible Electronics
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Solution Overview
Problem
Current methods for producing copper films on flexible substrates, such as PET, face challenges with high sintering temperatures and times, which deform the substrates and limit the use of copper-based inks in low-cost, high-density electronic applications, as existing copper formate complexes require longer sintering times and higher temperatures to achieve low resistivity values.
Innovation Solution
A copper precursor composition comprising a first copper complex coordinated with an imine or cyclic amine and a second copper complex coordinated with a primary or cyclic amine, allowing for thermal degradation at lower temperatures to produce metallic copper films with resistivity of 200 µΩ•cm or less, compatible with roll-to-roll processing and PET substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper formate complexes coordinated with conventional amines are used as precursors, then metallic copper films can be produced, but high sintering temperatures and long sintering times are required which cause substrate deformation and limit process efficiency
Solution Approach 1:
The patent modifies the chemical composition parameters of the copper precursor complex by coordinating copper formate with specific cyclic amine ligands (pyridine, piperidine, or their derivatives). This chemical parameter change enables the decomposition and reduction process to occur at lower temperatures (below PET deformation temperature) and shorter times, simultaneously achieving substrate integrity preservation and process efficiency improvement
Solution Approach 2:
The invention creates a composite copper precursor material consisting of copper formate coordinated with cyclic amine ligands. This composite structure combines the beneficial properties of copper formate (low decomposition temperature, complete reduction to metallic copper) with the stabilizing and modifiable properties of cyclic amine ligands, enabling controlled low-temperature sintering that prevents substrate deformation while maintaining high productivity
2Reliability
If high sintering temperatures are used to achieve low resistivity copper films, then electrical conductivity is improved, but PET substrates deform under tension
Solution Approach 1:
The patent changes the chemical composition parameters of the copper precursor to use cyclic amine-coordinated copper formate complexes. This modification alters the thermal decomposition characteristics, enabling the sintering process to occur at lower temperatures that do not exceed PET substrate deformation thresholds, thereby maintaining both electrical conductivity and substrate shape stability
Solution Approach 2:
The invention achieves local optimization by designing the copper precursor complex to decompose and reduce at a specific temperature range below PET deformation temperature. This localized temperature control ensures that the copper film formation occurs under conditions that preserve substrate shape integrity while still achieving the required electrical conductivity
3Reliability
If long sintering times are used to produce low resistivity copper films, then electrical performance is improved, but process cost and complexity increase for roll-to-roll applications
Solution Approach 1:
The patent modifies the chemical parameters of the copper precursor complex by incorporating cyclic amine ligands, which change the kinetic parameters of the decomposition and reduction reactions. This enables the sintering process to achieve complete copper formation in shorter times at lower temperatures, improving both electrical performance and process efficiency while reducing overall process complexity for roll-to-roll manufacturing
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 solution enables the production of copper films with low resistivity values at reduced sintering temperatures and times, preventing substrate deformation and facilitating the use of copper-based inks in flexible electronics, suitable for roll-to-roll printing and high-density designs.
Implementation Method 1
the copper precursor composition thermally is degradable at a temperature lower than a comparable composition comprising only the second copper complex under otherwise the same conditions to produce a metallic copper film
Data Source
Figure 1A~1B
Figure 2
Figure 3A
AI summary
A copper precursor composition contains: a first copper complex of an imine or a first cyclic amine coordinated to a first copper precursor compound; and, a second copper complex of a primary amine or a second cyclic amine coordinated to a second copper precursor compound. A copper precursor composition contains a copper complex of an imine coordinated to a copper precursor compound. The copper precursor composition is thermally degradable at a temperature lower than a comparable composition containing only primary amine copper complexes under otherwise the same conditions to produce a metallic copper film having a resistivity of about 200 μΩ-cm or less. Inks containing the copper precursor composition and a solvent may be deposited on a substrate and sintered to produce a metallic copper film. The substrate with the film thereon is useful in electronic devices.