Sintering of copper nanoparticles using intense pulsed light for screen-printed films on flexible substrate

Rapid growth in applications involving large area flexible electronics has led to wide adoption of the technique of sintering printed films using intense pulsed light due to its pulse mode operation and ability to reach high sintering temperatures without affecting the underlying substrate significantly. We study the sintering mechanisms of screen-printed thin films of copper nanoparticles on polyethylene terephthalate plastic substrates by varying the irradiance energy over a wide range to monitor conductivity and associated microstructure changes. We obtain optimized parameters which indicate the existence of a sharp threshold irradiance energy to kickstart sintering, and two distinct regimes beyond that. The low temperature regime has a high energy barrier while the high temperature regime has a substantially reduced energy barrier with a change of phase due to local melting.