Modelling of polyurethane polishing pad surface topography and fixed-point polished surface profile

Polishing process, is an important process of ensuring surface quality and precision. However, it is difficult to achieve quantitative material removal and polish to target surface profile accurately, due to the special structure characteristic of polishing pad and the complex contact mechanism between polishing pad-abrasive particle-workpiece surface. Therefore, this study proposes a statistic model for polyurethane polishing pad surface, which take into consideration of the circular hole size (Gaussian distribution), density and location distribution (random distribution) on polishing pad surface. On the basis of the polishing pad surface model, this study further establishes a predicting model for polishing surface profile through analyzing of the effective number of abrasive particles between polishing pad and workpiece, the real contact force between a single abrasive particle and workpiece surface, the single abrasive particle footprint, the overlapping and superimposing of abrasive particle footprint. A series of polishing pad comparative analysis and SiC polishing experiments with different parameters are performed. Both of the two models are validated through qualitative and quantitative comparisons of simulation and experiment results. The proposed models not only lay the foundation for an in-depth understanding of the material removal mechanism in polishing process with polyurethane polishing pads, but also meaningful to other polishing process with polyurethane polishing pads and the optimization of polishing process.