Disk drive spindle motor

Abstract

A small form factor disk drive having an extremely thin, high-energy product annular magnet within the spindle motor. The magnet includes twelve alternating poles disposed about the periphery and canted from the top edge to the bottom at a slight skew angle. The high-energy product magnet generates a high starting torque which obviates the use of low viscosity lithium bearing greases. A stator disposed concentrically within the magnet has three continuous coils, each coil wound around three spokes of the stator at 120 degree intervals, for a total of nine stator slots. The rotating spindle, bearings and stationary base are constructed of materials having similar coefficients of thermal expansion to reduce stresses on the bearings during periods of temperature elevation. An annular aluminum disk support sole bonds to a ledge on the spindle hub to facilitate machining and provide material compatibility. The disk drive includes various features for reducing the amount of contamination on the disk surface. A double groove bonding configuration eliminates adhesive runout and ensures a consistent bond strength.