Highly conductive copper nano/microparticles ink via flash light sintering for printed electronics

Area of Science:

• Materials Science
• Nanotechnology
• Additive Manufacturing

Background:

• Flash light sintering (FLS) is a rapid, high-throughput technique for fabricating conductive films.
• Controlling particle size is crucial for optimizing FLS of copper (Cu) inks.
• Understanding nano-/micro-particle interactions during FLS is key to enhancing film conductivity.

Purpose of the Study:

• To investigate the size effect of copper particles on flash light sintering of Cu ink.
• To assess the synergetic effects of mixed Cu nano- and micro-inks during FLS.
• To optimize ink composition and FLS parameters for high-conductivity Cu films.

Main Methods:

• Fabrication and characterization of Cu nano- and micro-particle inks.
• Optimization of nanoparticle-to-microparticle ratios and FLS parameters (energy density, pulse number, on/off-time).
• In situ monitoring of electrical resistance and temperature during FLS using Wheatstone bridge and thermocouple circuits.
• Post-sintering characterization using SEM, XRD, XPS, FTIR, and four-point probe measurements.

Main Results:

• The optimal nanoparticle-to-microparticle ratio for Cu ink was determined to be 50:50 wt%.
• Optimized FLS of the 50:50 Cu nano-/micro-ink resulted in the lowest electrical resistivity of 80 μΩ cm.
• The mixed nano-/micro-ink formulation demonstrated superior performance compared to pure nano- or micro-inks.

Conclusions:

• Particle size significantly impacts the flash light sintering behavior of copper inks.
• Synergistic effects between copper nanoparticles and microparticles enhance film conductivity.
• The optimized 50:50 Cu nano-/micro-ink offers a promising route for fabricating highly conductive films via flash light sintering.