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Micro/nanoscale characterization and modeling of thermal interface materials for electronics packaging

Posted on:2006-12-29Degree:Ph.DType:Dissertation
University:Stanford UniversityCandidate:Hu, XuejiaoFull Text:PDF
GTID:1451390005992612Subject:Engineering
Abstract/Summary:PDF Full Text Request
Thermal interface materials (TIMs) are used to thermally connect integrated circuits (ICs) to their cooling components. The performance of any thermal management solution for ICs, ranging from conventional heat sinks to advanced solutions like vapor chambers and microchannels, is limited by the thermal resistance of TIMs. This problem grows more acute with the increases in chip power densities and on-chip hotspots. However, in practice, the TIM performance always falls below expectation. Part of the problem is the confusion between the bulk behavior of attachment materials, often quoted by vendors, and their behavior in thin-film form within a package. Related to this problem is the fact that heat conduction physics in TIM layers is poorly understood due to a lack of microscopic characterization and modeling tools.; This work is focused on extracting the microscopic physics behind the thermal behavior of modern TIMs by developing high-resolution experimental and modeling tools. Diffraction-limited infrared microcopy is used to measure both cross-sectional and through-wafer lateral variations in TIM properties. Measured data, along with the results from microscopic simulation and modeling, provide deeper insight into the impacts of microscopic TIM structures on TIM performance. The impacts investigated include: (1) the changes of particle distributions near TIM boundaries, which result in higher temperature gradients and yield additional boundary thermal resistances; (2) the force interactions between particle-particle and particle-boundaries, which limit the TIM bold-line thickness; (3) voids and other defects at TIM interfaces deteriorate local TIM heat conduction.; This work is also dedicated to developing novel interface materials for next-generation electronics packaging applications with substantially improved thermal performance. Opportunities are nanostructured materials, particularly those related to carbon nanotubes (CNTs). Exploratory CNT-based solutions investigated in this work include (1) composites with homogeneous distributed CNTs and nickel particles; (2) interface structures with nanotubes vertically grown on silicon or metal substrates; (3) interface structures with two opposing CNT arrays. Heat conduction phenomena as well as possible mechanisms in these novel nanostructured materials are discussed.
Keywords/Search Tags:Materials, TIM, Thermal, Heat conduction, Modeling, Performance
PDF Full Text Request
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