Patent ID: 8792204

Claim:
A base plate of a disk drive apparatus which rotates a disk centered on a central axis which extends vertically, the base plate comprising: a motor base which is disposed around the central axis and is made of a metallic material of a first type; and a base body portion which extends radially outward of the motor base and is made of a metallic material of a second type; wherein a Young's modulus of the metallic material of the first type is larger than a Young's modulus of the metallic material of the second type; the motor base includes: a bearing mounting portion of a cylindrical or an approximately cylindrical shape which axially extends around the central axis; a bottom plate portion which extends radially outward from a lower portion of the bearing mounting portion; a wall portion which extends upward from an outer end portion of the bottom plate portion; a flange portion which extends radially outward from one of an upper end and a lower end of the wall portion; and a plastic deforming portion which extends radially outward from the other of the upper end and the lower end of the wall portion; the base body portion includes an inner end portion which is in contact with an outer circumferential surface of the wall portion; and the flange portion and the plastic deforming portion are respectively in contact with at least a portion of each of both axial end surfaces of the inner end portion of the base body portion.