Liquid Metal Concentration Effects on Thermal and Mechanical Properties in Elastomers

The escalating power density and consumption in electronic devices necessitate package-level heat-dissipating components with high isotropic thermal conductivity. Although polymers offer advantages such as low density, high strength, easy processability, chemical stability, and cost-effectiveness, they typically exhibit low intrinsic thermal conductivity values. Previous studies have explored the incorporation of gallium alloys into elastomeric matrices to enhance the composite material’s overall conductivity. However, conventional approaches involve aligning the thermally conductive filler, resulting in high thermal conductivity but significant thermal anisotropy. Yet, cross-plane thermal conductivity plays a vital role in dissipating heat from active devices and transmitting it to the surrounding environment. In this study, we investigate the impact of varying concentrations of eutectic gallium indium alloy (EGaIn) liquid metal within an elastomeric matrix without inducing filler alignment. Utilizing inplane and cross-plane thermal and mechanical characterization techniques, we aim to understand how this factor influences the isotropic enhancement of thermal conductivity and the mechanical performance of the material. Our findings reveal that, in the absence of induced alignment, thermal conductivity demonstrates a more isotropic increase with the concentration of liquid metal compared to alternative methods, all while maintaining mechanical performance similar to the matrix. These discoveries pave the way for advancements in bulk polymer-based composite materials for electronic applications.