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Corrosion control mechanism for hard disk drives Disclosure Number: IPCOM000016668D
Publication Date: 2003-Jul-08
Document File: 2 page(s) / 46K

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The Prior Art Database


A replaceable desiccant package is used to control relative humidity in a sealed disk drive.

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Corrosion control mechanism for hard disk drives

   The magnetic materials in the heads and disks of hard disk drives are often very susceptible to corrosion when exposed to high humidity in air. In the past, corrosion has been prevented by applying a thin film protective overcoat that protect the sensitive materials for the life of the drive. Also, drives often include some desiccant materials to moderate relative humidity (RH) swings in the drives. Two trends in hard drive development are making the current solution less viable. First, the need to reduce the magnetic spacing between the head and the disk, means the protective overcoats must get thinner and thinner. Current overcoats are a few nanometers in thickness. Thinner overcoats are increasingly difficult to produce that are effective in protecting the underlying materials from corrosion. Furthermore, many of the materials being considered for use in future heads and disks are more sensitive to corrosion than current materials. These two trends mean that drive will have to incorporate new methods of preventing corrosion. The most straightforward means of accomplishing this is to keep the RH in the drive below a maximum allowable level where corrosion rates are significant. The only way to guarantee this for a drive that may be in an uncontrolled environment for arbitrary periods of time is to hermetically seal the drive in a low RH atmosphere. We propose here a lower cost solution for drives which have limited exposure to uncontrolled environments. This includes server drives which normally operate in a controlled environment in the 30-50% RH range. However before being put in use, they may go through up to 6 months of storage in uncontrolled environments that can cause corrosion. These drives need a means of limiting the internal RH levels for the duration of the storage period.

This problem can be addressed by improved desiccant packaging sufficient to hold specified humidity levels for specified period (e.g. <60% internal RH for 6 months when exposed to 60 C/80% RH external environment). A desiccant containing package, as shown in the Figure below, drops into and seals a hole in the top (or bottom) cover after servo-write and particle count testing. Up through these tests, the drive is open to the atmosphere in a clean room environment where the RH may be in the 50% range. Typical desiccant packages are built into the drive so they become saturated at the high relative humidity level of the test en...