[en] Many pool boiling experiments to increase the nucleate boiling condition have been conducted and could get brilliant and challengeable results. The fact that the enhancement of CHF in pool boiling is strongly dependent on the surface wettability effect is also supported by other kinds of boiling experiments. In this regard, the excellent CHF condition in pool boiling could be achieved through some favorable surface modification which satisfies the optimized wettability condition. For finding the optimized condition, we design the special heaters to visualize how two materials, which have different wettability, affect the boiling phenomena. The special heaters have hydrophobic dots on the silicon surface. The peculiar teflon(AF1600) is used as the hydrophobic material. The contact angle of the heating surface which is made by teflon is 120 .deg. to water at the room temperature. The contact angle of the silicon surface is 60 .deg. at the room temperature. The experiment using the milli-sized hydrophobic dot is performed on the flat silicon surface