Polycarbonate blends and carriers for semiconductor wafers that are opaque to light of a particular wavelength

摘要

The present invention relates to ionic impurities, in particular sulfate ions and salts of chloride ions in an amount of less than 300 ppb, prepared by devolatilizing ionic impurities from a polycarbonate composition using about 1% by weight aqueous medium based on the weight of the polycarbonate composition Polycarbonate compositions and articles made from such polycarbonate compositions. Preferably, the devolatilization is carried out in an extruder while mixing the polycarbonate composition, preferably under vacuum. The extruded strand of the polycarbonate resin is also quenched in a water bath where the content of sulfate ions and chloride ions is less than 300 ppb each.