Abstract:In order to adjust the grain size and roughness of diamond film on the surface of microdrill to meet the requirements of drilling in PCB plate,by adjusting the flow ratio of argon and hydrogen,a series of diamond thin films were deposited on the silicon substrate by hot filament chemical vapor deposition(HFCVD)with methane,hydrogen and argon as the gas source.Raman spectroscopy,X ray diffractometer(XRD),scanning electron microscopy(SEM)and atomic force microscopy(AFM)were used to characterize the carbon bond structure,crystal orientation,grain size and surface roughness of the diamond films prepared at different flow rate of argon,respectively.The results show that,with the increase of argon flow rate,the graphite content in the diamond film is increased,the crystal plane orientation of the film tends to(111)crystal surface,the grain size is changed from micron scale(127 μm)to nanoscale,and the film roughness is first increased and then decreased.The lowest film roughness is 65 nm.Experimental results show that there is an optimum argon flow rate which makes the diamond film on the surface of microdrill have suitable structural characteristics,such as high carbon valence bond content,(111)crystal orientation,small grain size and low roughness to meet the requirements of ultrafine drilling in PCB plate.