Humidity rise after purge in micro-environments

The mass transport properties of four micro-environment (ME) materials were tested: polycarbonate (PC), poly(ether imide) (PEI), poly(ether ether ketone) (PEEK) and the Entegris barrier material (EBM). Permeation, diffusion and solubility coefficients of water vapor were measured at room temperature with 45% and 100% relative humidity (RH). These mass transport coefficients were used to estimate the humidity rise after purge in a 300 mm front opening unified pod (FOUP) constructed of these materials. PC was estimated to show 20% humidity rise two hours after purge. PEI was comparable to PC. PEEK showed better performance than PC or PEI. EBM showed the best water permeation resistance and the slowest and lowest humidity rise.