1. Field of the Invention
The present invention relates to a spindle motor and a disk drive apparatus.
2. Description of the Related Art
In hard disk drives and in optical disk drives, spindle motors arranged to rotate a disk around a center axis are typically used. These spindle motors include a stator portion fixed to a housing of an apparatus and a rotating portion arranged to support and rotate the disk. The spindle motors generate a torque around the center axis through the use of a magnetic flux generated between the stator portion and a rotating portion, to thereby rotate the rotating portion with respect to the stator portion.
The stator portion typically includes a coil arranged to generate the magnetic flux and an end of the wire of the coil is led to the outside of the spindle motor and connected to a predetermined circuit board. For example, Japanese Laid-Open Patent Publication No. 2005-210787 describes, in paragraph [0023], that the end of the wire of the coil is led to the outside of the motor and electrically connected to a land of a flexible wiring board by soldering.
In the spindle motor described in Japanese Laid-Open Patent Publication No. 2005-210787, the flexible wiring board is disposed under the coil, and the end of the wire is led out through a hole formed through the base and the flexible wiring board. Then, the end of the wire is electrically connected to the land disposed in the vicinity of the hole by soldering.
However, if the wiring board and the soldering portion are arranged beneath the coil, the thickness in the axial direction of the spindle motor will be increased as the thicknesses in the axial direction of the wiring board and the soldering portion is increased. In order to reduce the total thickness in the axial direction of the spindle motor while the wiring board and the soldering portion are disposed beneath the coil, it is necessary to design the base and the coil such as to have reduced thicknesses in the axial direction. However, when the size in the axial direction of the base is reduced, the base consequently becomes thinner which acts to decrease the rigidity of the base. Further, if the size in the axial direction of the coil is reduced, the number of windings of the conducting wire is decreased, so that the amount of torque for rotating the spindle motor is lowered.
On the other hand, if the wiring board and the soldering portion are arranged in positions on the outer side in a radial direction than the coil, it is necessary to lead the conducting wire drawn from the coil to the lower side of the base to the soldering portion on the outer side in the radial direction. However, this procedure leads to the thin insulating layer of the conducting wire becoming defective due to the contact between the conducting wire and the base.