Conformal laser printing and laser sintering of Ag nanoparticle inks: a digital approach for the additive manufacturing of micro-conductive patterns on patterned flexible substrates

The laser induced forward transfer and sintering of metal nanoparticle inks has been proven a key enabling technology for flexible electronics. Nevertheless, many challenges concerning the conformal processing of non-planar substrates incorporating thermally sensitive layers are yet to be addressed. In this work, we study the behaviour of conformal laser printing of silver nanoparticle inks on patterned samples comprising sensitive underlying structures, by correlating the laser sintering powers employed to the undesired effects on the adjacent interfaces. The latter include demanding surface topographies with periodic patterns and micro-components exhibiting aspect ratio in the nano to 100-micron scale. We investigate the contribution of crucial processing parameters, such as the per pulse energy, repetition rate and the pulse to pulse spatial and temporal overlap to the overall result. The demonstrated results validate the versatility of laser processing which can offer application specific solutions on different use cases involving multilayered and multimaterial electronics.