CC BY
20LP-O-1
Time-resolved shadowgraphy imaging of LIFT ejections, induced by pico- and nanosecond UV laser pulses
J. Miksys1, G. Arutinov2, G. W. Römer1 1 University of Twente- Chair of Laser Processing,
Department of Mechanics of Solids- Surfaces & Systems, Enschede, Netherlands 2TNO, Holst Centre, Eindhoven, Netherlands
In the field of printed electronics well know and established material deposition techniques, like screen printing, inkjet or dispensing are being pushed to its limits. Therefore, there is an increasing need for a new digital, more flexible and versatile technology, which allows high yield printing of depositions in the micrometer range and would be applicable to the wide range of materials. Laser-induced Forward Transfer (LIFT) already proved to be a potential technique meeting these demands [1]. LIFT is a digital, non-contact, nozzle-free technique, applicable for deposition of a wide range of materials, including pure metals, polymers, ceramics, semiconductors and biomaterials [2]. However, LIFT printing of complex materials, like silver nanoparticle inks remain challenging, due to the viscosity dependence of the shear rate of these materials. The complex nature of such materials narrows the range of the laser processing parameters of the well controlled LIFT ejections [3]. This has a key impact on the clean and reproducible depositions printing. Therefore, better understanding of the physical phenomena of the LIFT process is needed.
In this work, we present a comparative study on the effect of laser pulse duration on the ejections of donor material as well as on the influence to the deposition dimensions of viscous silver nanoparticle inks. In order to capture the dynamics of the LIFT jets, we employed time-resolved shadowgraphy (Figure 1) in both pico- and nanosecond LIFT setups. We found that in the lower laser fluence range, donor material is ejected at higher velocities when picosecond laser pulses are used, than when nanosecond pulses are used. However, as the fluence level is increased nanosecond laser pulses become as efficient, from an energy point of view, than when picosecond pulses are used. This trend is observed in time-resolved LIFT ejection dynamics, as well as in the analysis of depositions. These differences are attributed to a difference in heat dissipation in the donor material, as well as to the shear-thinning property of the silver nanoparticle ink.
Fig. 1. Time-resolved shadowgraphy image sequence of LIFT of silver nanoparticle ink.
References
[1] M. Morales, D. Munoz-Martin, A. Marquez, S. Lauzurica, C. Molpeceres, Laser-Induced Forward Transfer Techniques and Applications, Second Edi, Elsevier Ltd., 2017.
[2] A. Piqué, P. Serra, Laser Printing of Functional Materials: 3D Microfabrication, Electronics and Biomedicine, 2018.
[3] C. Boutopoulos, I. Kalpyris, E. Serpetzoglou, I. Zergioti, Laser-induced forward transfer of silver nanoparticle ink: Time-resolved imaging of the jetting dynamics and correlation with the printing quality, Microfluid. Nanofluidics. 16 (2014) 493-500.
