Bending Fatigue of Laser-sintered Copper Films on Plasma Bombarded PI Substrate

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 (Rnom: 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 O2 plasma caused a greater surface energy (especially polar component), higher surface roughness, and thereby exhibit superior bending fatigue resistance.