Power control unit and method of assembling the same

A method of assembling a power control unit applied to an electrified vehicle driven by a vehicle drive unit including a transaxle case that houses at least one of a rotating electrical machine and gears, the power control unit being disposed on the transaxle case, the power control unit including a plurality of semiconductor devices configured to perform an electric power control of the rotating electrical machine, an electronic circuit board including a soldered portion for attaching the plurality of semiconductor devices to the electronic circuit board, and a power control unit case (PCU case) that houses the plurality of semiconductor devices and the electronic circuit board, and an upper cover that forms at least a part of an upper surface of the PCU case, the upper cover including a first component and one or more second components having a lower rigidity than the first component, wherein the first component includes a portion that forms the upper surface of the upper cover of the PCU case, and a part of the portion includes an opening on the upper surface, comprising:

• attaching the plurality of semiconductor devices to a support member of the PCU case;
• attaching the electronic circuit board to the first component;
• stacking the electronic circuit board attached to the first component and the plurality of semiconductor devices attached to the support member;
• performing soldering of the electronic circuit board and the plurality of semiconductor devices which have been stacked, the soldered portion being arranged on a surface of the electronic circuit board located on a side of the upper cover;
• and
• assembling the one or more second components with the first component after the soldering, so that the one or more second components covers the opening and covers the soldered portion.