title: In situ assembly in confined spaces of coated particle scaffolds as thermal underfills with extraordinary thermal conductivity.
abstract: In situ assembly of high thermal conductivity materials in severely confined spaces is an important problem bringing with it scientific challenges but also significant application relevance. Here we present a simple, affordable, and reproducible methodology for synthesizing such materials, composed of hierarchical diamond micro/nanoparticle scaffolds and an ethylenediamine coating. An important feature of the assembly process is the utilization of ethylenediamine as an immobilizing agent to secure the integrity of the microparticle scaffolds during and after each processing step. After other liquid components employed in the scaffolds assembly dry out, the immobilization agent solidifies forming a stable coated particle scaffold structure. Nanoparticles tend to concentrate in the shell and neck regions between adjacent microparticles. The interface between core and shell, along with the concentrated neck regions of nanoparticles, significantly enhance the thermal conductivity, making such materials an excellent candidate as thermal underfills in the electronics industry, where efficient heat removal is a major stumbling block toward increasing packing density. We show that the presented structures exhibit nearly 1 order of magnitude improvement in thermal conductivity, enhanced temperature uniformity, and reduced processing time compared to commercially available products for electronics cooling, which underpins their potential utility.
authors.affiliation: Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich , Sonneggstrasse 3, 8092 Zurich, Switzerland.
authors.forename: Guo
authors.initials: G
authors.lastname: Hong
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Schutzius
authors.forename: Severin
authors.initials: S
authors.lastname: Zimmermann
authors.forename: Brian R
authors.initials: BR
authors.lastname: Burg
authors.forename: Jonas
authors.initials: J
authors.lastname: Zürcher
authors.forename: Thomas
authors.initials: T
authors.lastname: Brunschwiler
authors.forename: Giulia
authors.initials: G
authors.lastname: Tagliabue
authors.forename: Bruno
authors.initials: B
authors.lastname: Michel
authors.forename: Dimos
authors.initials: D
authors.lastname: Poulikakos
keywords: confined space; electronics cooling; hierarchical composite; liquid bridge; thermal conductivity