Optimization of the Polishing Parameters for the Glass Substrate of STN-LCD

Abstract

The optimal control parameters for the polishing of the glass substrate of super-twisted nematic-liquid crystal display (STN-LCD) were explored. The Taguchi technique was used to formulate the experimental layout. The surface characteristics caused by the polishing process were analyzed with atomic force microscopy (AFM). The signal-to-noise (S/N) ratio and analysis of variance (ANOVA) were employed to determine the optimal levels and the order of significance of the identified critical parameters affecting quality. A confirmation test under the optimal process parameters was carried out to verify the effectiveness of the Taguchi technique. The results indicated that, for the surface finish, the platen speed was the most significant parameter followed by down pressure, oscillation speed, and time. The optimum combination of process parameters for excellent surface roughness in the polishing experiment were: platen speed, 40 rpm; down pressure, 4.9 kPa; oscillation speed, 4 rpm; time, 10 min.

Keywords:

• Analysis of variance (ANOVA)
• Atomic force microscopy (AFM)
• Cerium oxide
• Confirmation test
• Down pressure
• Glass substrate
• Nanomorphology
• Orthogonal array
• Platen speed
• Polishing process
• S/N ratio
• Soda Lime glass
• STN-LCD
• Surface roughness
• Taguchi method

ACKNOWLEDGMENT

This research was sponsored by the National Science Council, Taiwan, ROC, under contract no. NSC 95-2815-C-239-006-E.

Notes

where

***Most significant parameter.

**Significant parameter.

^a95% confidence level, F _{0.05, 2, 2} = 19.0.

^b75% confidence level, F _{0.25, 2, 2} = 3.0.