Abstract: A magnetic disk device according to one embodiment includes a base, five or more magnetic disks in the base, a head actuator, and a spindle motor. The base has a bottom wall having a second thickness and a side wall. The spindle motor includes a sleeve with a first hole, fixed to the bottom wall, a shaft inserted in the first hole rotatably, and a hub rotatable integrally with the shaft. The hub includes a first part, a second part extending from a lowermost surface of the first part in a first direction being from the magnetic disks toward the bottom wall, and a third part having a first thickness and extending from a lowermost surface of the second part in a second direction orthogonal to the first direction. A value obtained by dividing the second thickness by the first thickness is greater than or equal to 1.89.

Abstract: A magnetic disk device according to one embodiment includes a base, five or more magnetic disks in the base, a head actuator, and a spindle motor. The base has a bottom wall having a second thickness and a side wall. The spindle motor includes a sleeve with a first hole, fixed to the bottom wall, a shaft inserted in the first hole rotatably, and a hub rotatable integrally with the shaft. The hub includes a first part, a second part extending from a lowermost surface of the first part in a first direction being from the magnetic disks toward the bottom wall, and a third part having a first thickness and extending from a lowermost surface of the second part in a second direction orthogonal to the first direction. A value obtained by dividing the second thickness by the first thickness is greater than or equal to 1.89.

Abstract: A flexible printed circuit assembly includes a flexible printed circuit board including a base portion and a relay portion extending from a first edge of the base portion and capable of being bent relative to the base portion, a first reinforcing member disposed at the relay portion, and a second reinforcing member attached to a first region of the base portion that includes a second edge opposite to the first edge and having an engaging portion. The first region of the base portion is capable of being folded back towards a second region of the base portion that includes the first edge, and the engaging portion of the second reinforcing member is capable of being engaged with the first reinforcing member.