Experimental investigations on super-smooth polishing of strontium titanate based ceramics substrates

Strontium titanate (SrTiO3) is a new type of multi-function electronic ceramic material. SrTiO3 ceramic substrates with a high dielectric constant can be obtained by non-pressurised sintering using ultrathin blanks, which result in the characteristics of thin, soft, brittle and warped. So that SrTiO3 ceramics substrates need to be polished to improve surface quality and dimensional precision before application. In this research, polish experiments with various processing parameters on the surface roughness, the material removal rate and the surface morphologies of SrTiO3 ceramic substrates were conducted. The results show that the SrTiO3 ceramic substrate with a highest quality surface was obtained in the condition: employing a brown polyurethane pad to polish the substrates at a polishing velocity of 45 r/min. Meanwhile, the slurry flow rate, the concentration of the polishing slurry and the polishing pressure were 20 ml/min, 4 wt% and 15.043 kPa, respectively, which rates with an overall and a partial surface roughness of Ra 0.01 µm and Ra 4 nm, respectively. While some new micro-scratches were generated on the surface of the SrTiO3 ceramics substrate in the polishing process because the embedding and scratching of abrasive particle led to expose the inherent pores and grain boundaries.