Laser forward transfer of conductive inks

Abstract

One of the most used inks in printed electronics is silver paste, which is extensively used in screen printed circuits. In this work the feasibility of Laser-Induced Forward Transfer (LIFT) technique was investigated for transferring screen printing silver paste. It was possible to print several droplets at different laser pulse energies for a certain donor-acceptor gap. After that, two studies were carried out: the analysis of the deposited droplets and the characterization of the dynamics of the material transfer. An approximately linear trend in the radius-energy dependence was observed, and thicknesses of the printed droplets were of the order of a few microns. The transfer dynamics was characterized by means of a time-resolved imaging method, showing three different stages on the bubble evolution: bubble expansion, bubble burst and bubble retraction. Jet formation never took place as it happens in low-viscosity inks. Results in both experiments were conclusive and consistent with each other