The first and second embodiments describe four layers substrates with through holes. The third to fifth embodiments describe six layer substrates with build-up layers. However, the types of substrates and number of layers are not limited to the examples in the above-described embodiments. For example, the number of layers may be three, five, seven, or more. The type of substrate may also be different. The number and the arrangement of the through hole vias, the front side vias, the middle layer vias, and a back side vias may be appropriately set based on manufacturing and assembly considerations (e.g., based on the degree or state of solder rise), and the inner vias may be omitted.

In the above-described embodiments, the power supply terminal and the ground terminal are inserted into the substrate from the surface opposite to the motor (i.e., the cover facing surface), and soldering is performed on the motor side surface. In other embodiments, a connector may be provided between the substrate and the motor, and the power supply terminal and the ground terminal may be inserted into the terminal connection portion from the motor side. In such a case, since the soldering is performed on the cover facing surface of the substrate, the above-described embodiments may be applied in a similar manner, assuming that the first surface described in the embodiments above would be the second surface in this case. As such, the teaching in the above-described embodiments may be adapted to accommodate instances where the soldering is performed on the cover facing surface of the substrate.