Author: Gilad Nave
Date: September 13th, 2023 at 1:00pm
Zoom Link: https://umd.zoom.us/j/5095422567
Location: EGR-2164, Martin Hall
Dr. Francis Patrick McCluskey, Chair
Dr. Mohammad Al-Sheikhly, Dean’s Representative
Dr. Hugh Bruck
Dr. Diganta Das
Dr. Abhijit Dasgupta
Dr. Peter Sandborn
Title: Electrical and Structural Formation of Transient Liquid Phase Sinter (TLPS) Materials During Early Processing Stage
The growing demands of electrification are driving research into new electronic materials. These electronic materials must have high electrical conductivity, withstand harsh environments and high temperatures and demonstrate reliable solutions as part of complete electronic packaging solutions. This dissertation focuses on characterizing the initial stage of the manufacturing process of Transient Liquid Phase Sinter (TLPS) alloys in a paste form as candidates for Pb-free high-temperature and high-power electronic materials.
The main objective of this dissertation work is to investigate the factors and decouple the multiple cross effects occurring during the first stage of TLPS processing in order to improve the understanding of material evolution. The work proposes, develops, and conducts in-situ electrical resistivity tests to directly measure material properties and analyze the dynamics at different stages of the material’s evolution. The research explores various factors, including alloying elements, organic binders, and heating rates, to understand their effects on the development of electrical performance in electronic materials. More specifically, the work examines the performance of Ag-In, Ag-Sn and Cu-Sn TLPS paste systems. Additionally, packing density and changes in cross-section are investigated using imaging techniques and image processing to gain insights into the early formation of the material’s structural backbone. An Arrhenius relationship together with Linear Mixed Models (LMM) techniques are used to extract the activation energies involved with each of the processing stages. The study then develops procedures to model different states of the TLPS microstructures at different heating stages based on experimentally observed data. Using these models, the study uses Finite Element Method (FEM) analysis to verify the experimental results and gain a better understanding and visualization into the involved mechanisms. This investigation not only sheds light on the material’s behavior but also has implications for robust additive manufacturing (AM) applications.