Sid Pathak: Understanding solders in terrestrial vs microgravity environments

Title

Understanding the Local Structure-Property Relationships of Solders in Terrestrial vs. Microgravity Environments using Electron Microscopy and Nano-mechanical Testing.

Mentor

Sid Pathak

Department

Chemical and Materials Engineering

Biosketch

I plan to integrate education and research to provide a multitude of enrichment opportunities for the undergraduate students to gain exposure to advanced research in the areas of experimental materials science and mechanics. Students participating in this project will be trained in research methods structural and chemical analysis (X Ray Diffraction, Scanning Electron Microscopy, and Transmission Electron Microscopy), synthesis, and nano-mechanical testing. Select students will also have the opportunity to present their work at international conferences, as well as publishing their work in peer-reviewed journals, depending on the quality of work performed.

I have mentored multiple undergraduates at UNR, both from programs such as the McNair Scholars Program, underrepresented students (3 female and one Hispanic), as well as regular undergraduates. Undergraduate students in my lab have gone on to receive a number of fellowships and scholarships, including the 2018-19 Nevada NASA Space Grant Consortium Undergraduate scholarship, 2018 TMS Structural Materials Division (SMD) Undergraduate Scholarship, 2017 Nevada Undergraduate Research Award and the Nevada National Science Foundation's Experimental Program to Stimulate Competitive Research (NSF EPSCoR) 2016 Academic Year Undergraduate Research Opportunity Program (UROP) fellowship.

For more deatils Check out our webpage at wolfweb.unr.edu/homepage/spathak

Project Overview

An integrated experimental and computational effort is proposed to characterize both the microstructure and resultant micro-to-nano mechanical response of solders in terrestrial vs. microgravity environments, 1g vs. ~1×10^-5g. Results from the In-Space Soldering Investigation (ISSI) experiments performed aboard the International Space Station (ISS) have shown that soldering in microgravity is expected to be considerably different than their ground based counterparts due to Earth's natural convective flow and buoyancy effects being minimized in microgravity during melting and solidification. The ISSI data has demonstrated that a lack of buoyancy forces in microgravity can internally trap the flux created during soldering at interfaces, such as repair joints. We hypothesize that such internal porosity can be detrimental to the desired strength of the joint, as well as its thermal and electrical conductivity - our study aims to develop a comprehensive understanding of these effects in the millimeter-sized solders using an array of nano-mechanical testing tools such as indentation and focused ion beam (FIB) fabricated micro-pillar compression and micro tensile testing, and nanoscale electrical contact resistance (nano-ECR) measurements. Results from this study will be instrumental in enhancing our fundamental understanding of the effects of surface tension driven convection phenomena during solidification processing operations such as brazing, soldering, and welding. Furthermore, the microgravity experiments represent a lowest gravity boundary condition. As such, these results could also be useful in predicting solidification behavior on other lower gravity environments (e.g. moon or Mars).