Statistical designs of experiments were applied in order to understand the effect of processing variables on the brightness of inorganic electroluminescent displays. The main effects and interaction of phosphor and dielectric layers are estimated to be statistically significant. Additional improvement was made on removing the pores in the thick films, using the defoaming in pastes and cold isostatic pressing in bonding the top and bottom parts of the inorganic electroluminescent devices. Such optimization contributed to the reduction in the corresponding threshold voltage and enhancement in the brightness.