Influence of commercial PVD deposition parameters when producing tin coatings

Physical Vapor Deposition (PVD) is a coating technique that relies on the creation of a vapor phase, under vacuum conditions, that condenses on a substrate to form a coating. PVD coatings of titanium nitride are commonly used in functional applications to promote faster cutting speeds and to prolong tool life, leading to operational cost savings and improved productivity. Some of the limitations of a PVD coating for functional applications are based on the coating thickness, where a lower coating thickness reduces the wear volume available on a contacting surface. Also of issue is the presence of globules or "macros" in the coating resulting in a non-homogeneous, rougher surface. The formation of macros in a PVD coating is particularly associated with the cathodic arc PVD system. This study investigated the effects of chamber pressure, substrate bias voltage and arc current and their interaction, on physical parameters of titanium nitride coatings deposited in a commercial cathodic arc PVD system. Scanning Electron Microscopy (SEM) was used to provide a measure of the consistency of the coating topography and an indication of the number of macros in the coatings. Atomic Force Microscopy (AFM) was used to provide numerical values for the roughness of the coatings. The information from these two instruments was combined to provide the optimum processing conditions for the reduction of macros.