Disc drive with small air gap between back iron and spindle hub

摘要

An apparatus for attaching the rotor to the spindle hub and minimizing the effects of the difference of thermal expansion of the rotor and the spindle hub upon the discs during thermal cycling. To facilitate minimizing the thermal effects, the rotor outer diameter is smaller than the inner diameter of the spindle hub such that an air gap is maintained between the two parts. One end of the cylindrical back iron portion of the rotor is attached to a radially extending wall portion closing one of the two axial ends of the cylindrical portion of the spindle hub. In other words, the rotor is end-mounted inside the spindle hub. The attachment is accomplished by using screws which extend through the radial extending portion of the spindle hub into one end of the cylindrical back iron portion of the rotor or, in the alternative, by epoxying the two elements together.