Organizational Unit:
School of Materials Science and Engineering
School of Materials Science and Engineering
Permanent Link
Research Organization Registry ID
Description
Previous Names
Parent Organization
Parent Organization
Organizational Unit
Includes Organization(s)
ArchiveSpace Name Record
Publication Search Results
Now showing
1 - 3 of 3
-
ItemEnhancing The Properties Of Copper Foam Wicks Using Graphene Coatings For High-Performance Vapor Chambers And Heat Pipes(Georgia Institute of Technology, 2023-05-02) Moss, James AlexanderWith the increasing thermal densification of consumer and portable electronics, the implementation of two-phase capillary flow-driven structures (e.g., vapor chambers, heat pipes) in thermal management has grown exponentially. These structures utilize the latent heat of evaporation of a working fluid along with the thermal and capillary capabilities of a wick to efficiently mitigate hot spots through heat spreading; however, material development for improved thermal capabilities of these two-phase wick systems is underdeveloped for what is needed in future electronic packages. As a result, this research explores the use of conformal graphene coatings deposited on open-cell copper foams to enhance their properties and performance. A controlled chemical vapor deposition process was utilized to conformally coat monolayer graphene on different copper foam densities with varying pore sizes and 3D connectivity. The thermal, electrical, and mechanical properties were then characterized before and after the graphene was deposited to understand the effect of the coating on the foams. Permeability and wettability were also evaluated to understand the potential of the coating on high-performance wicks. An electroless copper deposition process was then developed to deposit a conformal intermediate copper layer that could separate parallel graphene networks with further sequential deposition of alternating graphene and copper layers. This thesis reports the resulting improvements in wick properties and performance from graphene coatings, establishing this method as a promising pathway for compact and highly efficient in-package heat spreading solutions, and provides design guidelines to maximize benefits from this material innovation with considerations of ease of processability and cost.
-
ItemModeling, Design and Demonstration of a Single, Innovative Metallurgical System for Socketable and Surface-Mountable Board-Level Interconnections(Georgia Institute of Technology, 2021-05-01) Gupte, Omkar DeepakOEM Microprocessors have conventionally been packaged using Land Grid Array (LGA) designs, press-fitted into sockets for ease of reworkability. However, Ball Grid Array (BGA) packages have recently become mainstream for surface mount (SMT) applications, driven by the need for miniaturization of electronic systems. While SMT processes and applications with BGA are becoming more widespread, the market need for sockets is also expected to increase significantly over the next decade. While microprocessor companies would benefit from producing a single BGA package design applicable in both socketing and SMT applications, this raises challenges for the OEM supply chain as no BGA-compatible socket is currently available. Enabling universal BGA packages compatible with both socketing and SMT processes is, therefore, critical to this industry transition. Current BGA architectures are not compatible with socketing applications as the mechanical contact between the Au paddle and the solder sphere leads to undesirable reactions, increasing the contact resistance and degrading reworkability over time. To address this challenge, surface modification of BGA spheres with multilayered thin-film metallic coatings such as Ni-Au and Bi-Au is proposed to maintain a non-reactive noble metal interface when used in a socket. This presentation provides details of the studies conducted in this research, including (1) design, diffusion modeling, and finite element modeling of such coatings with a fundamental understanding of the trade-offs between SMT and socketing applications, (2) the development, characterization and optimization of the coating on solder spheres and attach processes using an in-house developed, hybrid sputtering/electroless deposition process and conventional mass reflow with solder paste, respectively, as well as (3) reliability characterization of the modified BGA packages in socketing and SMT applications. The results establish the proposed approach as a promising technology towards the development of a reliable, universal BGA solution.
-
ItemSintered nanoporous copper die-attach interconnections: Syntheis and characterization(Georgia Institute of Technology, 2020-08-06) Mohan, KashyapTo address the demand for higher electrification and efficiency in automobiles and aviation, there is an increasing focus on developing new power electronics packaging technologies which can enable the wide-bandgap devices to operate at their full potential. In particular, new die-attach interconnection materials are needed with thermal stability at temperatures greater than 250°C, superior thermal and electrical conductivities for higher thermal dissipation and power handling. In this thesis, low-temperature, low-pressure sintering of nanoporous copper (Cu) films to form all-Cu die-attach joints is proposed as the next-generation die-attach technology capable of addressing the above-mentioned challenges. To realize the above objectives, two research tasks were identified and demonstrated. In the first task, fabrication o nanoporous Cu by chemical dealloying of amorphous Cu alloy ribbons and electroplated Cu-Zn films was explored. Fundamental relationships between the Cu-Zn electroplating parameters, composition of the electroplated films, morphology of the dealloyed films, and residual Zn after dealloying were established. Based on the results, guidelines were also framed for large-scale fabrication of nanoporous Cu films. In the second task, the effect of the sintering temperatures and sintering atmospheres on the sintering kinetics of nanoporous Cu film was explored, followed by the development of assembly parameters to enable good metallurgical bonding between nanoporous Cu and Cu metallizations. The initial assembly trials gave promising results and Cu-Cu joints with shear strengths>40MPa were achieved.