An improved cooling mechanism for a power electronics device is provided. More specifically, a cooling mechanism is provided wherein an air directing structure with a finite air-flow resistance is deployed in a cooling channel adjacent to a heatsink in a first cooling zone, such that some portion of the cooling air is forced through the heatsink while the rest of the cooling air bypasses the heatsink to provide additional cooling air to a second cooling zone. Additionally, the air-flow resistance of the air directing structure can be chosen so that the fan operates at its optimal point (maximum power input to the air).