Drop-on-Demand Embedding of Liquid Metals to Produce Thermal Pads with Advanced Properties
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Authors
Bandala Sanchez, Erick
Issue Date
2025
Type
Thesis
Language
en_US
Keywords
Ecoflex , Effective thermal conductivity , Fumed silica , Gallium , Thermal interface material
Alternative Title
Abstract
Thermal pads play a vital role as interface materials, facilitating heat transfer from central processing units (CPUs) to heat sinks, enabling rapid temperature reduction and extending the lifespan of electronic components. However, conventional lab-scale and commercially available thermal pads often face challenges such as low thermal conductivity, limited maximum operating temperatures, and insufficient mechanical flexibility, especially under the demanding conditions of high-performance or supercomputing environments. In this work, we introduce a drop-on-demand embedding (DODE) technique to fabricate next-generation thermal interface materials (TIMs). This approach allows precise printing of liquid metal droplets, specifically gallium, into a composite matrix that is both thermally compliant and mechanically adaptable. The matrix is composed of fumed silica and Ecoflex, each chosen for its specific functional advantages. Fumed silica improves the rheological behavior and thermal tolerance of the matrix, while Ecoflex provides elasticity and softness to ensure intimate contact with complex CPU surfaces, thereby optimizing thermal transfer. The dispersed gallium droplets form effective heat conduction pathways, substantially enhancing the overall thermal conductivity of the composite thermal pad. Systematic characterization reveals that DODE-printed pads can operate at temperatures up to approximately 250℃, exhibit a favorable elastic modulus of around 0.4 MPa, and have an effective thermal conductivity ranging from 4 to 11 W/mK, depending on the operating temperature (100℃ to 250℃). These results emphasize the synergy between gallium droplet dispersion and matrix composition in producing highly customizable, high-performance TIMs. Overall, this work highlights the versatility and scalability of the DODE method as a powerful fabrication strategy for advanced thermal pads tailored to meet the rigorous demands of next-generation electronics, including supercomputers, high-power graphic processing units (GPUs), and advanced data center processors.