Dielectric Coating of Cathodes for Microfabrication Using Electrochemical Method

Pulse microelectrochemical machining (ECM) by bipolar current is a method allowing the manufacturing of microholes and micropatterns. In many cases, microholes with parallel walls and accurate micropatterns can only be manufactured with the application of an electrically isolating coating to the side surfaces of the cathode. The goal of this research was to find a durable coating for this process. Epoxy resins, Teflon, and diamond-like carbon are considered as dielectric cathode coatings. Different aspects of the working environment of these coatings in the pulse bipolar ECM process, such as electric field, chemical composition, and physical influences of the electrolyte, are analyzed. The main reasons for the low process durability of coatings are poor adhesion and harsh chemical and physical environments. The most promising coating for the process is diamond-like carbon, which shows significantly better performance than the other coatings. Improved adhesion of a coating to the cathode can dramatically improve its durability in the pulse bipolar ECM environment and therefore permits an efficient manufacturing process.