Analysis on the lapping uniformity of MPCVD polycrystalline diamond wafer

Abstract

In the process of free abrasive lapping, the driving mode and process parameters directly affect the flatness and surface roughness of the workpiece. To explore the effect of free abrasive lapping process parameters based on rotary swing drive on the planarization of MPCVD polycrystalline diamond film, a kinematic model of single abrasive grain in rotary swing drive plane lapping process was established in this study. According to the actual lapping process, this paper adopts the multi-abrasive random distribution model for computer simulation and introduces the uniformity dispersion coefficient of multi-abrasive trajectory to analyze the diamond surface abrasive trajectory. The results suggest that when the speed ratio equals 0.5, the dispersion coefficient of abrasive trajectory is the largest; when the speed ratio is less than or equals 0.5, the dispersion coefficient of abrasive trajectory is positively correlated with the speed ratio; and when the length of the swing arc chord of the lapping workpiece disc is larger than the diameter of the diamond film, the motion trajectory of the abrasive particles relative to the whole diamond film surface is evenly distributed. The optimal lapping parameters are obtained by computer simulation. Through the 2 inch polycrystalline diamond lapping test, the final surface PV value of diamond is 2.4 μm, the surface roughness Ra is 139 nm and the material removal rate dMRR is 10.1 μm/h.

Keywords

• rotary swing drive
• polycrystalline diamond film
• plane lapping
• trajectories of grits
• surface figure precision
• material removal rate