A shrouded hard disk drive includes one or more contamination filter
cavities embedded within the shroud for capturing airborne contaminants
circulated within the drive during normal operation. The present invention
takes advantage of naturally occurring radial and circumferential velocity
differences between air at the edges of the disk pack and the air at the
filter cavity entrance opening (i.e., the inner circumference of the
shroud) to redirect airflow through a filter positioned within the one or
more filter cavities. After air passes through the filter, it exits
through a filter cavity exit opening positioned in proximity to either in
the area between the disks, or the area above or below the disk pack. In
order to trap particles entrained in the airflow, the filter can be made
of a variety of materials, including: air porous plastic film, expanded
polyvinyl chloride plastic, a micro porous polymer of cellulose ester
formed around a polyester web, a lint-free weave, an adsorbent, an
electret, or an electrically conductive material.