Date: Thursday, Nov 17th
Presenter: Prof. Rajiv Malhotra, OSU Advanced Manufacturing
Fabrication of functional devices by additive deposition and sintering of nanoparticles as building blocks is emerging as a key manufacturing paradigm for flexible and conformal electronics. Significant research has gone into one integral process in the above paradigm, i.e., additive deposition (as films or patterns) of nanoparticles via inkjet printing, aerosol jet printing and microextrusion. The other key part of the above paradigm is sintering of the deposited nanoparticles at high speeds and over large areas. This talk will focus on one such sintering process, i.e., Intense Pulsed Light (IPL) sintering, which uses large-area (12x0.75), broad-spectrum (300-700nm), pulsed light (3µs-3ms) as the energy field to sinter the nanoparticles and has the potential to meet the above needs.
I will first review IPL in terms of its advantages over conventional nanoparticle sintering, its current materials capability window, and current understanding of densification and temperature rise in the process. Then, I will describe my recent work on IPL, using Ag nanoparticles as a model system, and the discovery of a negative feedback coupling between densification and temperature rise in the process. The implications of this observation on tailoring IPL parameters to control densification will be discussed. I will further show preliminary work on IPL of CuxS nanoparticle films and on the effect of nanoparticle size distribution on temperature rise and densification in IPL. I will then briefly describe our recent efforts in demonstrating the integration of lower-cost, lower-energy, broad-spectrum, desktop optical sources with desktop inkjet printing and aerosol jet printing as well as future work on incorporating Digital-Micromirror-Devices for large-area patterned sintering.
Dr. Rajiv Malhotra finished his PhD and postdoctoral work at Northwestern University, and joined the department of Mechanical Engineering at Oregon State University in January 2014. His broader research interests lie at the intersection of materials and manufacturing, involving a combination of experimental work and multiphysical modeling to understand and control material behavior during manufacturing processes. His current interests span process behavior at different length scales including out-of-chamber nanoparticle sintering using energy fields such as visible light, UV-light and near-field microwaves at the nano-micro length scales; and low-temperature, tool-less sheet forming at a macroscopic length scale. More recently he has been exploring the integration of these processes with each other, and with other processes, to create next-generation manufacturing capabilities. Since 2008 he has published 37 peer-reviewed papers and is the recipient of two U.S. patents. His research is funded by the National Science Foundation, Department of Energy, the Walmart Manufacturing Innovation Grant and by industry.