BASE MEMBER, MOTOR, AND DISK DRIVE APPARATUS

摘要

A thin base member for use in a disk drive apparatus in which a bearing mechanism and an actuator are arranged includes a plurality of lower recess portions, a C-shaped smooth surface, and a fan-shaped recess portion. The C-shaped smooth surface is arranged in a region of an upper surface of the base member around the region where the bearing mechanism is arranged and the C-shaped smooth surface has a height constant or substantially constant in a circumferential direction. At least a portion of each of the lower recess portions is provided below the C-shaped smooth surface, in which the C-shaped smooth surface has a cross section positioned at the lower recess portions to protrude in a direction toward which the upper surface of the base member faces or in a direction toward which the lower surface of the base member faces.