High-speed multi-jets printing using laser forward transfer: time-resolved study of the ejection dynamics

Abstract

This paper extends the current understanding of the laser-induced forward transfer (LIFT) process to the multi-jets ejection problem. LIFT has already been used to print micrometer-sized droplets from a liquid donor substrate with single pulse experiments. Here we study the dynamics of the high-speed multi-jets formation from silver nanoparticles ink films with a time-resolved imaging technique. A galvanometric mirrors head controls the spacing between adjacent pulses by scanning the focused beam of a high repetition rate UV picosecond laser along an ink-coated donor substrate. The laser pulses interact with the liquid film and generate cavitation bubbles that propel the ink away from the substrate and form the jets. When the spacing between consecutive pulses is substantially higher than the maximum diameter of the bubbles, there is no interaction between adjacent jets, and these remain unperturbed. However, when the pulses are brought closer significant jet-jet interaction takes place, which results in a clear deviation from the single jet dynamics. Thus, the cavitation bubbles acquire different shapes, the ink is ejected faster and along different directions depending on the spacing between the pulses, and each bubble alters the evolution of the previous one and shifts away from it.

Laser‐Induced Forward Transfer: Fundamentals and Applications

“…The combination of both laser repetition rate and the speed of relative translation of the donor/receiver system with respect to the laser beam determine the resulting printing speed in a LIFT setup. Commercially available lasers can easily deliver pulses at repetition rates of several MHz, and through galvo‐scanners and polygon mirrors it is possible to deflect the laser beam at speeds of hundreds and even thousands of m s −1 . These characteristics make LIFT a very competitive direct‐writing technique in terms of speed.…”

Microcapacitors with controlled electrical capacity in the pF–nF range printed by laser-induced forward transfer (LIFT)

“…viscous inks (typical viscosity of $10 cps, 10-20% of silver nanoparticles content), were largely studied by different techniques such as inkjet and screenprinting, but also by LIFT, for the fabrication of organic thin film transistors [13]. In a previous study we investigated the possibility of fabrication of conducting lines using the ink and a high-speed printing process [22][23][24]. The resulted conducting lines were continuous and very thin ($80 nm).…”

Copper micro-electrode fabrication using laser printing and laser sintering processes for on-chip antennas on flexible integrated circuits

“…laser spot size, laser fluence, inks properties etc.) [40]; second, jet impact on already printed ink (splashing effect) [41]. In this case, the debris must be attributed mainly to the unstable successive jets as the high viscosity of the ink significantly limits the splashing effect.…”