Vacuum arc evaporation inherently emits droplets or particles. Using pulsed discharge currents (such as implemented with the Laser-ArcTM technology) reduces this effect but cannot completely suppress it. This results in particle induced growth defects and large coating roughness, which are not acceptable for some applications. Thus IWS engineers developed technologies to filter the carbon plasmas and separate out most droplets and particles. Plasma filtering enables the deposition of ta-C coating with significantly reduced defect densities. These coatings can be used without additional lapping steps even for demanding applications.
A plasma filter was developed especially for the Laser-ArcTM technology and the coating module LAM 500. The filter replaces the adapter flange, which usually connects the source chamber to the coating machine. In filtered operation the technology deposits smooth ta-C coatings of low defect densities, which significantly outperform unfiltered coatings. The deposition rate is reduced by about 40% compared to unfiltered deposition.