Executive Summary : | A significant surge in the use of different SiC polytypes is being witnessed in the fabrication of various micro-components like microchannels in microelectronic systems to dissipate high heat fluxes, micro molds for optical dies, micro-slots for micro-fuel cells, micro-turbine, and atomizers for aerospace applications, etc. The high thermal conductivity, extreme chemical inertness, high-temperature strength, and wear resistance make them suitable for such applications.Due to very low fracture toughness, machining SiC ceramics via conventional methods is complex as they involve plastic deformation. Until now, micro-features on ceramics were fabricated via processes viz. reactive ion etching (RIE), molding, micro-USM, laser micro-machining, and micro-EDM. However, the above methods possess some inherent limitations. For instance, the etching fails to generate high aspect ratio micro-parts, the micro-USM and laser micro-machining fail to generate micro-components with higher surface finish and fewer micro-cracks, and micro-EDM leaves a white layer with micro-cracks on the finished surface. Although cracks were primarily reduced by applying ductile regime micro-grinding, it costs productivity. In this regard, heat-assisted micro-grinding, which employs an external heat source preceding the chip removal process such as laser-assisted micro-grinding and electro-chemical discharge assisted micro-grinding, has significantly improved the productivity and surface finish with reduced edge cracks. But they lack positional accuracy as they execute two processes sequentially. This issue was also mitigated by employing thermal assistance and material removal simultaneously via a single tool as in micro electro-discharge grinding (micro-EDG); however, the tools in this process are in the form of a disc that is incapable of fabricating micro-cavities on the workpiece. In contrast, a micro-EDG tool in the shape of a pencil (diameter less than 1mm) made of tungsten carbide with a polycrystalline diamond (PCD) tip could be a better option for fabricating micro-cavities in SiC ceramics which lacks recognition to date. And hence, it is of utmost importance to develop the process for successful and controlled micro-EDG on SiC wafers using a pencil-shaped PCD micro-tool. |