The heat dissipation performance in a conventional chip on board (COB) LED module is limited by the very low thermal conductivity of the dielectric layer. In this study, an enhanced model is proposed to achieve effective heat dissipation using an aluminum nitride (AlN) insulation plate instead of the dielectric layer. Initially, the geometric configuration of the enhanced model was optimized by using response surface methodology. The effects of each design parameter were also analyzed in terms of the one-dimensional and spreading thermal resistances. In the optimized enhanced model, the junction temperature and total thermal resistance were 24.1% and 55.2% lower, respectively, than the conventional COB module with the copper-based substrate. At the heat input of 15 W, the luminous efficacy of the optimized enhanced model was about 13.9% higher than that of the conventional COB module. (C) 2014 Elsevier Ltd. All rights reserved.