Influence of pretreatment and deposition parameters on the properties and cutting performance of NCD coated PCB micro drills

Nowadays, a broad growing market of printed circuit board (PCB) micro drills has been developed. In this study, nano- crystalline diamond (NCD) coated printed circuit broad (PCB) micro drills are fabricated by the hot filament chemical vapor deposition (HFCVD) technique. The main factors affecting their cutting performance are generally their breaking strength, film-substrate adhesion, continuity and smoothness of coatings, and coating thickness. Consequently, the corresponding pretreatment and deposition parameters including pretreatment zone, pretreatment time in Murakami's reagent, substrate temperature during the deposition process, as well as the deposition time are optimized. A novel pretreatment zone, only involving cutting zone of micro drill, is proposed by cantilever flexural tests. Then, the substrate temperature is optimized to be about 850 °C by temperature simulation and its verification tests. Furthermore, the pretreatment time in Murakami's reagent and the deposition time are determined to be 10 min and 2 h by high speed dry drilling of copper clad laminates (CCLs).