Fabrication of Anisotropic Low-Melting-Point Alloy Particles for Directional Electrical and Thermal Transport

Anisotropic metal particles have attracted considerable attention because their direction-dependent geometry can facilitate directional electrical and thermal transport while maintaining relatively low filler contents. Conventional liquid metal, especially gallium-based liquid metal, particles can be processed at room temperature and readily deformed into anisotropic shapes. However, their fluidity may cause particle coalescence during storage or under pressure, resulting in poor shape retention and limited mechanical stability. In this study, a low-melting-point alloy is investigated as a solidifiable alternative for producing anisotropic metal particles. The fabrication strategy is initially adapted from a previously reported method (ACS Appl. Mater. Interfaces 2025, 17, 51, 69908–69918) for anisotropic liquid metal particles, and key processing parameters, including solvent type, processing time, and surfactant concentration, are systematically varied to control particle deformation, dispersion stability, and aspect ratio. Unlike room-temperature liquid metals, low-melting-point alloys can be processed in the molten state and subsequently solidified, potentially preserving the anisotropic morphology while suppressing particle coalescence during storage and mechanical deformation. This work establishes a process-development framework for anisotropic low-melting-point alloy particles and investigates their potential as mechanically stable, directionally functional fillers. The resulting particles are expected to be suitable for applications where directional electrical or thermal transport is important, such as anisotropic conductive films (ACFs) and thermal interface materials (TIMs).