Silicon carbide (SiC)-based inverter have gained a significant interest due to its low power consumption. However, with miniaturization and larger operating current, the heat flux of the SiC chip will reach 500 W/m², which is approximately 5 times higher than the critical heat flux (CHF) of water on a smooth surface. In this study, a lotus-type porous copper (lotus copper) having a unidirectional pore structure is utilized to cause the "breathing phenomenon". This induces continuous liquid supply and vapor discharge. The heat transfer surface has 1.0-mm-square grooves at a pitch of 1.57 mm in one direction. The 10-mm-square lotus copper is joined on the grooved heat transfer surface with solder. To evaluate the effects of a thickness and pore diameter of the lotus copper, boiling curves of saturated pool boiling are obtained for distilled water under atmospheric pressure. The thicknesses of the lotus copper are 1, 2, 3 mm and three different pore diameters are used for 1-mm and 3-mm-thick lotus copper. According to the experimental results, the heat transfer coefficient is improved with the decreasing thickness. On the other hand, the critical heat flux is independent of the thickness and pore diameter. To discuss the results, two models are considered: 1) a fin model for the heat transfer coefficient and 2) a flooding model for the critical heat flux. For the heat transfer coefficient, the fin model shows that 1-mm-thick lotus copper has larger heat transfer surface area compared with that of 2-mm and 3-mm-thick lotus copper. This promotes boiling in the entire surface of the lotus copper. In the flooding model for the critical heat flux, disruption of liquid supply by the generated vapor, which is called flooding phenomenon is considered. If the flooding phenomenon causes CHF, the CHF values derived from the flooding model are the same order that obtained in the experiment.