Patent ID: 8254056

Claim:
A magnetic disk drive, comprising: a box body having a head disk assembly built therein for writing data to, and reading data from, a magnetic recording medium, wherein the box body includes a wall surface having a circular stepped breathing hole drilled therein to penetrate therethrough, the circular stepped breathing hole comprising two portions, the two portions comprising an upper side portion and a lower side portion, wherein the circular stepped breathing hole includes a large-diameter hole and a small-diameter hole disposed below the large-diameter hole, the large-diameter hole forming the upper side portion and the small-diameter hole forming the lower side portion of the breathing hole; and wherein the breathing hole includes a pore waterproof body having therein a plurality of pores disposed in the small-diameter hole and prevents entry of a liquid in the box body by using surface tension of the liquid when the liquid enters the pores and a fiber waterproof body comprising a waterproof fiber layer disposed in the large-diameter hole above the pore waterproof body.