Air-Sinterable Copper Precursor Inks via Mixed Bidentate/Tridentate Ligands: Synergistic Oxidation Resistance and...

Area of Science:

• Materials Science
• Chemistry
• Electrical Engineering

Background:

• Copper conductive inks are a cost-effective alternative to silver-based inks.
• Oxidation poses a significant challenge to copper ink performance.
• Existing single ligand systems lack sufficient coordination stability.

Purpose of the Study:

• To investigate mixed-ligand strategies for improving the atmospheric stability of copper precursor inks.
• To develop oxidation-resistant copper-based conductive inks.
• To provide practical guidelines for ink formulation.

Main Methods:

• Designed five ligand systems: a base system with 2-amino-2-methyl-1-propanol (AMP) and four hybrid systems.
• Tested hybrid systems combining AMP with secondary ligands: 1,3-diaminopropane, 3-amino-1-propanol, isopropanolamine, and serinol.
• Analyzed oxidative stability, electrical resistivity, and processability.

Main Results:

• The AMP-serinol mixed-ligand system demonstrated enhanced oxidative stability with tridentate binding.
• Low resistivity (69.8 ± 5.5 μΩ·cm) was maintained after 60 days in ambient air.
• A multiscale protection mechanism involving coordination, encapsulation, and microstructure was identified.

Conclusions:

• Mixed-ligand coordination, particularly tridentate binding, is key to developing stable copper conductive inks.
• The ligand-engineering approach provides fundamental insights and practical guidelines for ink formulation.
• Direct-write fabrication confirmed the ink's processability and reliability for circuit patterns.