Silver dendrite-based nanocomposites for current cutting-off fuse

Microelectronics and micromechanical systems (MEMS) are gaining popularity by virtue of small size, high integration, diverse functionalities, mass production and low cost. However, the existing current cutting-off fuse components can hardly be used in a microelectronics or micromechanical system to realize circuit protection due to their large size and high fusing current. Herein we report a novel current cutting-off fuse component based on printed electrically conductive nanocomposites (ECCs), which are composed of silver microdendrites with fractal morphology as the fusible conductive fillers and the thermosetting resin matrix. The silver paste was pasted between two copper electrodes with controlled space. The current cutting-off performance of the fuses was investigated within different silver fillers, various paste sizes, and diverse electrode spaces. The results show that, the silver dendrite-based paste can be fused at a relative low current due to its abundant nano-sized rims at the edge of the dendrite branches. Furthermore, the minimum fusing current (530 mA) was achieved when the silver flake-based paste was dispensed between two electrodes with distance of 100 μm and width of 30 μm. It is obvious that the fusing current attenuates gradually with the increase of space between two copper electrodes, and the silver paste in large spot size possesses higher fusing current than in small one. The scanning electron microscopy (SEM) analyses suggest that the silver fillers go through the melting and shrinking stages during the fusing process, thus the adjacent silver fillers separate to break the circuit. Considering the low material cost and negligible environmental risk, this novel current cutting-off fuse can provide cost-effective and environmental-friendly protection for MEMS devices.