Monsanto Company

Rickey Leonard Salter

Rudolph Hugo Petrmichl

Victor M Zeeman, Jr

Ray Hays Venable

The invention is a method and apparatus for the RF plasma deposition of diamond-like carbon (DLC) and related hard coatings onto the surface of drills; especially microdrills such as printed circuit board drills and printed wire board drills, using a mounting means connected to a source of capacitively coupled RF power. A key feature of the apparatus is that the drills to be coated are the only negatively biased surfaces in the capacitively-coupled system. According to the method, the surface of the drills to be coated are first chemically de-greased to remove contaminants, and inserted into the electronically masked coating fixture of the present invention. The electronically masked fixture includes the powered electrode, the portion of the drills to be coated, an electrically insulated spacer, and an electrically grounded shield plate. Next, the loaded fixture is placed into a plasma deposition vacuum chamber, and the air in said chamber is evacuated. Gas is added to the vacuum chamber, and a capacitive RF plasma is ignited, causing the surface of the drills to be sputter-etched to remove residual contaminants and surface oxides, and to activate the surface. Following the sputter-etching step, a silicon-containing material layer is deposited by capacitive RF plasma deposition. This silicon-containing material layer may be either an adhesion layer for subsequent deposition of DLC, or may be 'Si-doped DLC' ('Si-DLC'). If this silicon-containing layer is an adhesion layer, the next step in the process is deposition of a top layer of either DLC or Si-DLC by capacitive RF plasma deposition.

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Northampton, PA, United States of America

Rickey Leonard Salter