Development of a hybrid coating process for deposition of diamond-like carbon films on microdrills

A hybrid physical vapor deposition-electron cyclotron resonance-chemical vapor deposition (PVD-ECRCVD) coating system has been developed and used to deposit a Ti/TiN/TiCN/DLC multilayer coating on the microdrills. In order to improve the adhesion strength of the DLC films, functionally graded Ti/TiN/TiCN supporting multilayers were pre-deposited initially on the microdrill by PVD with high rate coating sources based on a combined arc evaporation and magnetron sputtering process. The Ti/TiN/TiCN/DLC multilayer coating was completed in one deposition cycle batch. The drilled hole quality was evaluated by the nail heading (the cross section of a nail with a conical head) and surface roughness in the hole wall, and the microdrilling performance measured in terms of printed circuit board (PCB) production was investigated. Functionally, in adopting a microdrill coated with the DLC film, the inspected drilled hole quality was found to be superior than that of uncoated ones, and the drilling lifetime was significantly improved about 2.5 times.