Thermal Conductivity Enhancement of Soft Polymer Composites through Magnetically Induced Percolation and Particle–Particle Contact Engineering

Matthew Ralphs, Wilson Kong, Robert Wang, Konrad Rykaczewski

    Research output: Contribution to journalArticle

    Abstract

    Despite major advancements in the performance of thermal interface materials (TIMs), contact resistance between components persists as a major thermal bottleneck in electronics packaging. In this work, the thermal performance of composite TIMs is enhanced through a synergistic coupling of magnetic alignment and engineered particle coatings that reduce the thermal resistance between particles. By itself, magnetically induced percolation of nickel particles within a cross-linked silicone matrix doubles the thermal conductivity of the composite. This process significantly increases contact between particles, making the interfacial particle–particle resistance a major contributor to the composites thermal performance. The resistance at these interfaces can be reduced by introducing soft metal (silver) or liquid metal coatings onto the nickel particles. Compressing powder beds of these hybrid particles reveals that, dependent on coating thickness, the contact engineering approach provides multifold increases in thermal conductivity at mild pressures. When dispersed in a polymer matrix and magnetically aligned, the coated particles provide a threefold increase in composite thermal conductivity, as compared to unaligned samples (up to nearly 6 W m−1 K−1 with volumetric fill fraction of 0.5). For equivalent coating thicknesses, silver coatings achieve better performance than liquid metal coatings.

    Original languageEnglish (US)
    Article number1801857
    JournalAdvanced Materials Interfaces
    DOIs
    StatePublished - Jan 1 2019

    Fingerprint

    Thermal conductivity
    Composite materials
    Polymers
    Metal coatings
    Coatings
    Liquid metals
    Silver
    Nickel
    Electronics packaging
    Contact resistance
    Polymer matrix
    Heat resistance
    Silicones
    Hot Temperature
    Powders
    Metals

    Keywords

    • boundary resistance
    • liquid metal
    • polymer composites
    • silver
    • thermal interface materials

    ASJC Scopus subject areas

    • Mechanics of Materials
    • Mechanical Engineering

    Cite this

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    abstract = "Despite major advancements in the performance of thermal interface materials (TIMs), contact resistance between components persists as a major thermal bottleneck in electronics packaging. In this work, the thermal performance of composite TIMs is enhanced through a synergistic coupling of magnetic alignment and engineered particle coatings that reduce the thermal resistance between particles. By itself, magnetically induced percolation of nickel particles within a cross-linked silicone matrix doubles the thermal conductivity of the composite. This process significantly increases contact between particles, making the interfacial particle–particle resistance a major contributor to the composites thermal performance. The resistance at these interfaces can be reduced by introducing soft metal (silver) or liquid metal coatings onto the nickel particles. Compressing powder beds of these hybrid particles reveals that, dependent on coating thickness, the contact engineering approach provides multifold increases in thermal conductivity at mild pressures. When dispersed in a polymer matrix and magnetically aligned, the coated particles provide a threefold increase in composite thermal conductivity, as compared to unaligned samples (up to nearly 6 W m−1 K−1 with volumetric fill fraction of 0.5). For equivalent coating thicknesses, silver coatings achieve better performance than liquid metal coatings.",
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