Micro electrical discharge milling of a monocrystalline silicon complex micro-cavity

Abstract

This paper develops a new method to restrain the fracture of monocrystalline silicon machining in EDM (Electrical discharge machining) through controlling the topography of single discharge crater. By this method, the complex 3D micro-cavity can be machined without obvious fracture. The fracture of monocrystalline silicon in EDM was revealed according to the EDM pits and the machining debris, then it is inferred that there are two ways to cause fractures, one is the breakages at the edge of the effective-removing crater, and the other way is the deformation accumulation caused by the superposition of the ineffective-removing crater. Then, it was found that if the morphology of single discharge crater can be controlled, the less fracture can be guaranteed during the manufacturing. Using narrow pulse width discharge, plenty of experimental tests were carried out focused on carters and surface of monocrystalline silicon with different machining parameters, with the assistance of characterization and analysis. Using these new results, the complex 3D structure is machined by layered compensation strategy and step-by-step milling strategy. It is found from the as-machined complex 3D cavity that it has no obvious defects at the edges, and the fracture is controlled.