Year

2019

Degree Name

Master of Philosophy

Department

Institute for Superconducting and Electronic Materials

Abstract

Gallium (Ga) and its alloys are in a liquid state at room temperature, and their melting points are either lower than, or close to, room temperature, which endows them with additional advantages in comparison to solid metals. For example, they are flexible, stretchable and deformable at room temperature. Also, they display excellent thermal and electrical conductivities with low viscosity and non-toxicity. Therefore, great improvements have been achieved in developing multifunctional devices by using Gabased liquid metals, including actuators, flexible circuits, bio-devices and self-healing superconductors. Nowadays, electronic devices have achieved great impact in modern society, however, electronic devices are small and are usually further subdivided into “integrated circuits”. This miniaturization has been a central background for the booming of modern electronic technology. Micro/nano sized conductive particles have been used for the assembly of electronic devices, but the synthesis procedure for conventional conductive particles is complicated and expensive, so a novel material for electronic assembly has been developed and is described in this Thesis.

In this research, we present a facile synthesis method for liquid metal nanoparticles via laser irradiation. Compared with traditional probe sonicator-made particles, the produced size is more uniform by the laser method, and the size can be controlled well by simply controlling the laser energy density. The eutectic EGaInSn alloy particles (EGaInSn) produced in this research were covered by a thin oxide skin, which could be broken by external stimulation. In addition, we reported that the conductive particles in existing anisotropic conductive adhesives could be replaced by EGaInSn nanoparticles (NPs). In such a system, EGaInSn particles remain fluid and soft and the oxide shell can be broken when required by applying mild pressure. By adjusting the concentration of liquid metal, an anisotropic conductive path can be achieved by anisotropic merging of liquid metal droplets.

In summary, either bulk material or nanoparticles of Ga based liquid metals display potential for electronic devices fabrication and electronic assembly.

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.