Laser sintering of Cu paste film printed on polyimide substrate

We here show that highly conductive copper films are obtainable from Cu paste by laser sintering. The Cu paste synthesized using an organo-metallic compound was screen-printed onto polyimide substrate and the printed films were scanned by an ultraviolet laser beam at 355 nm under nitrogen atmosphere. Very compact microstructure was observed throughout the whole thickness and the sintered films were mechanically robust. Although Cu is known susceptible to oxidation, no Cu oxides were incorporated into the film during laser sintering. An electrical resistivity of 1.86 × 10−5 Ω cm was obtained. This resistivity is several orders of magnitude lower than those reported for the copper nanoparticle paste thermally sintered under N2 or H2 atmosphere.

► Highly conductive Cu films are printed on polyimide substrate by sintering Cu paste with laser. ► Sintered films are mechanically robust and very compact microstructure is observed throughout the whole thickness. ► Laser-sintered film shows an electrical resistivity comparable to that of thermally sintered film.