Influence of the Gap between Substrates in the Laser-Induced Transference of High-Viscosity Pastes.

Juan José Moreno-Labella,Carlos Molpeceres,David Munoz-Martin,Guillermo Vallejo,Miguel Morales

doi:10.3390/ma14195567

Juan José Moreno-Labella, Carlos Molpeceres + Show 3 more

Open Access

https://doi.org/10.3390/ma14195567

Copy DOI

Abstract

Laser-induced forward transfer for high-viscosity—of Pa·s—pastes differ from standard LIFT processes in its dynamics. In most techniques, the transference after setting a great gap does not modify the shape acquired by the fluid, so it stretches until it breaks into droplets. In contrast, there is no transferred material when the gap is bigger than three times the paste thickness in LIFT for high-viscosity pastes, and only a spray is observed on the acceptor using this configuration. In this work, the dynamics of the paste have been studied using a finite-element model in COMSOL Multiphysics, and the behavior of the paste varying the gap between the donor and the acceptor substrates has also been modeled. The paste bursts for great gaps, but it is confined when the acceptor is placed close enough. The obtained simulations have been compared with a previous work, in which the paste structures were photographed. The analysis of the simulations in terms of speed allows for predicting the burst of the paste—spray regime—and the construction of a printability map regarding the gap between the substrates.

Highlights

Laser-induced forward transfer for high-viscosity—of Pa·s—pastes differ from standard LIFT processes in its dynamics
The transference after setting a great gap does not modify the shape acquired by the fluid, so it stretches until it breaks into droplets
There is no transferred material when the gap is bigger than three times the paste thickness in LIFT for high-viscosity pastes, and only a spray is observed on the acceptor using this configuration

Summary

Introduction

Laser-induced forward transfer (LIFT) techniques are a group of processes for the transference of a great variety of materials, such as biological fluids, metallic inks and pastes, or solid pellets of material [1]. High-viscosity pastes are complex solutions, halfway between colloids and fluids They are formed by suspending micron-size particles of a metallic material in an organic solvent (DuPont 9450, DuPont, Bristol, UK), so their proportion is critical to determine their properties. This behavior is explained rheologically and not thermally, because the aPmVo1u9nBt).oTfhviaspboerhiazvediorpiassteexpislavienreydsrmheaolll,oagnicdaltlhyeahnedant ocot nthdeurcmtiaolnly,tabkeecsaupsleacteheatama soluonwteorf tvimapeosrciazleedtphaasntethise vmeraytesrmialaltlr,aannsdfetrheencheea[1t 2c]o.nPdruovctiidoendtathkaets tphleayceaaret ansoltohwoemr toigmeenesocaulse mthaatneritahles mbuattearsiaulstpreannssifoenreonfcepa[r1t2ic].lePs,rothveidreedistahawtitdheeyraanrgeenfootr hthoemgoivgeennevoiuscsomsitayte. The mean curvature of the interface can be calculated as follows:

Numerical Model for Pressure Function

Model Validation

Results