Highly Reliable Laser-sintered Copper FilmsTransformed from Cu2O Nanoparticles by Plasma Modification of the Polymeric Substrate Surface

In this study, cuprous oxide composite pastes were screen- printed on the plasma-modified polyimide substrates to form highly conductive copper films by means of laser sintering. The average resistivity of reduced and sintered copper films can be down to 4 μΩ-cm (theoretical resistivity of copper is 1.8 μΩ-cm). Cyclic bending test of the copper films on PI substrates (R
nom
: 2.91 mm, and bending frequency: 1 Hz) were carried out to evaluate the fatigue reliability, and the variation of the electrical resistivity with the bending cycle number was also recorded. Experimental results show that C=O and C-OH surface binding, and surface roughness, all affect the adhesion of sintered copper films. Among the tested plasma atmospheres, O
2
plasma caused a large amount of C=O and C-OH surface binding, thereby exhibit superior bending fatigue resistance.