Key Laboratory of Micro-nano Electronic Devices and Smart Systems of Zhejiang Province, College of Information Science & Electronic Engineering, Zhejiang University, Hangzhou 310027, China.
Nanoscale. 2019 Mar 21;11(12):5441-5449. doi: 10.1039/c8nr09503e.
Stable and reliable electrical properties of interconnects and interfaces between flexible/stretchable and rigid materials/components are essential for the practical applications of flexible electronic devices and systems; traditional metal thin films and hard solder interconnects and interfaces can no longer meet these requirements. As an emerging soft conductive material, liquid metal has the advantages of high stretchability, flexibility, etc. over other soldering materials, and it has been used in interconnects and interfaces for some flexible electronics. In this study, we report a detailed investigation on the reliability and stability of liquid metal-based interconnects/interfaces under various mechanical deformations, including extension, bending, torsion, high frequency vibration and high temperature operation; we also compared the results with those of interconnects and interfaces using silver paste, the most commonly used solder for flexible electronics. The results show that liquid metal interconnects and interfaces maintain high conductivity under severe elongation up to 95% and 130%, upon bending with a curvature radius as low as ∼1.5 mm, and upon twisting up to 360°; meanwhile, interconnects and interfaces with silver paste filler lose electrical conductivity at elongations of 0.6% and 60%, respectively. Liquid metal interconnects and interfaces show superior performance to silver paste interconnects and interfaces because liquid metal can be re-shaped to make good contact with objects, while the silver paste becomes solid and rigid once dried and thus loses contact with other objects under deformation.
互连和界面的稳定可靠的电气性能在柔性/可伸缩和刚性材料/组件之间是柔性电子设备和系统的实际应用至关重要;传统的金属薄膜和硬焊互连和接口不再满足这些要求。作为一种新兴的软导电材料，液态金属具有高延展性、灵活性等优点与其他焊接材料相比，已应用于一些柔性电子产品的互连和接口中。在本研究中，我们详细研究了液态金属基互连/界面在各种机械变形下的可靠性和稳定性，包括拉伸、弯曲、扭转、高频振动和高温操作;我们还将结果与使用银膏的互连和界面的结果进行了比较，银膏是柔性电子产品中最常用的焊接材料。结果表明，液态金属互连和界面在高达 95%和 130%的严重拉伸、曲率半径低至约 1.5mm 的弯曲以及高达 360°的扭转下保持高导电性;同时，银膏填充的互连和界面在 0.6%和 60%的伸长率下分别失去电导率。液态金属互连和界面的性能优于银膏互连和界面，因为液态金属可以重新成型以与物体保持良好接触，而银膏一旦干燥就会变成固体和刚性，因此在变形时会失去与其他物体的接触。
