With the progress of electrification and digitalization of mobility such as automobiles, robots, and electric power networks, power electronics technology is drawing attention. Here, it is necessary to realize low power loss by utilizing the high-speed switching characteristics of power semiconductors and to meet EMC standards such as noise, and the pattern design and board specifications of the printed circuit board that affect these are required. It is an issue. This time, we will introduce the design and development method of printed circuit boards on which power semiconductors are mounted, including actual measurements and simulations.