Patent ID: 8737018

Claim:
A spindle motor arranged to have a recording disk and a clamper mounted thereon, the spindle motor comprising: a rotating portion including a rotor hub and a rotor magnet including the rotor hub fixed thereto, and arranged to be rotatable about a central axis; and a stationary portion including a stator arranged opposite to the rotor magnet; wherein the rotor hub includes: a hub circular plate portion arranged to extend radially with respect to the central axis; a hub cylindrical portion arranged to extend axially downward from an outer circumferential portion of the hub circular plate portion; and a disk mount portion arranged to extend radially outward from the hub cylindrical portion; an outer circumferential portion of the hub cylindrical portion includes a hub screw portion arranged to have the clamper screwed thereto; the hub screw portion includes at least: a first hub screw groove; a first hub screw thread arranged to be adjacent to the first hub screw groove; and an upper flank and a lower flank arranged to together define the first hub screw thread; the outer circumferential portion of the hub circular plate portion includes a hub slanting surface arranged to connect with the first hub screw groove; and a length of the hub slanting surface is longer than a length of the upper flank.