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Reliable electrical conductive path in a rotating shaft motor system. Disclosure Number: IPCOM000100679D
Publication Date: 2005-Mar-16
Document File: 2 page(s) / 128K

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Disclosed is a 360 degree ring-shaped electric conductive epoxy to ensure a reliable electric conductive path between a fluid dynamic bearing sleeve and bracket in a rotating shaft spindle motor used in hard disk drives.

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Reliable electrical conductive path in a rotating shaft motor system .

  The construction of a rotating shaft motor does not ensure a reliable electrical conductive path between the fluid dynamic bearing sleeve and mounting bracket interface when these two motor components are adjoined with an adhesive material. This electrical path is critical for dissipating charge build-up and minimizing the potential difference voltage between the heads and disk system in hard disk drives. Without a reliable electric conductive path, the magnet heads are susceptible to damage by electrostatic discharge(ESD), resulting in the form of signal loss such as reversal of the magnet head polarity and at worst, electrical breakdown in the head to disk interface. In the past, an electrical conductive epoxy has been applied in a finite number of locations around the two adjoining component surface; however, this solution has resulted in motors showing delamination of the epoxy with the limited amount of epoxy used.

This problem can be addressed by increasing the amount of epoxy and consequently the applied surface area to maximize the reliability of the conductive path.

Fig. 1 illustrates a spindle motor with a conductive epoxy ring glued to the adjoining region between the sleeve and bracket. The adhesive is electroconductive and is a silver-based conductive material with epoxy resin as a binder. After applied, the adhesive has to be completely cured and it also has to be free of outgass...