Sintering Copper Nanoparticles with Photonic Additive for Printed Conductive Patterns by Intense Pulsed Light

Area of Science:

• Materials Science
• Nanotechnology
• Electrical Engineering

Background:

• Developing conductive thin films is crucial for flexible electronics.
• Intense pulsed light (IPL) sintering offers a rapid method for materials processing.
• Improving inter-particle connections and film integrity is key for high conductivity.

Purpose of the Study:

• To formulate a novel ink for creating conductive copper thin films using IPL sintering.
• To enhance the sintering process and film properties by modifying copper nanoparticles (CuNP).
• To achieve high conductivity and stability in printed copper tracks on flexible substrates.

Main Methods:

• Synthesizing a cuprous oxide (Cu2O) shell over copper nanoparticles (CuNP) to aid sintering.
• Utilizing intense pulsed light (IPL) sintering with and without a reductant.
• Incorporating cupric oxide nanoparticles (CuONP) to enhance light absorption and reduce voids.
• Optimizing CuNP/CuONP ratios and IPL parameters for film conductivity.

Main Results:

• Multiple IPL pulses with a 2s off-time were initially required to prevent film cracking and achieve low resistivity (10^-5 Ω·cm).
• Addition of CuONP enabled single-pulse IPL sintering and reduced film resistivity.
• An optimal CuNP/CuONP ratio of 1/80 yielded a film with 7 × 10^-5 Ω·cm resistivity (~25% bulk copper conductivity) at 3.08 J/cm^2.
• The resulting conductive copper films demonstrated excellent stability, maintaining resistance after 10,000 bending cycles.

Conclusions:

• The developed ink formulation and IPL sintering process effectively produce highly conductive and stable copper thin films.
• The incorporation of CuONP is a key innovation for achieving efficient single-pulse sintering and high conductivity.
• This technology holds promise for applications in flexible electronics, such as printed conductive tracks.