Spindle motor having magnetic circuit for stator and rotor magnet, and storage disk drive having the same

摘要

A spindle motor includes a base portion; a stator arranged above the base portion; a rotor hub including a cover portion positioned above the stator, and a side wall portion arranged to extend downward from an outer edge of the cover portion; a rotor magnet positioned radially outward of the stator, and fixed to an inner circumferential surface of the side wall portion of the rotor hub; and a bearing mechanism arranged to support the rotor hub and the rotor magnet to be rotatable. A height of the rotor magnet as measured in an axial direction is preferably in a range of about 2 mm to about 3 mm (both inclusive), and a height of a stator core of the stator as measured in the axial direction is preferably in a range of about 50% to about 75% (both inclusive) of the height of the rotor magnet.