The development and the implementation of Silicon Carbide (SiC) devices are steadily increasing in the high-power converter of aircrafts. In this paper, a PCB-based heavy copper busbar is introduced for 250kW inverter system operated at 40,000 ft. Finite-element analysis (FEA) simulation studies of the PCB busbar are used to optimize the electric field intensity and busbar efficiency in this digest. Busbar modeling technic is also introduced for current distribution analysis and loss extraction. The Experimental results of partial discharge behavior and DPT are shown for insulation design and loop inductance verifications.