ECDM methods for fluidic interfacing through thin glass substrates and the formation of spherical microcavities

Electrochemical discharge machining (ECDM) involves the electrolytic formation of a gas film at a tool electrode with high current density discharges and Joule heating for local material heating and removal. The ECDM process is ideally suited for low density glass through-hole machining for applications such as fluidic interconnection. In this paper, we describe a simple and robust ECDM cell arrangement and present optimum conditions for rapid and reproducible through-hole machining in both 500 mu m thick and fragile 180 mu m thin borosilicate glass substrates. Both anodic and cathodic methods were evaluated and the results offer additional insight into the complex and polarity-dependent mechanisms involved in the ECDM process. The anodic process produces unique spherical cavity microstructures, presenting a new capability for glass microfabrication.

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