Analysis of the stains produced by metal particle tapes on helical scan heads in data recording applications

The increasing demand for high capacity data storage requires decreasing the head-to-tape gap and reducing the track width. A problem very often encountered is the development of adhesive debris on the heads at low humidity and high temperatures. The debris lead to an increase of space between the head and media, and thus a decrease in the playback signal. In this study on stains, samples of ferrite used in DDS (Digital Data Storage) heads in conjunction with MP (metal particulate) tapes have been subjected to a series of experiments including staining using a loop tester and high humidities, and their surface analysed using XPS (X-ray Photon Spectroscopy). The results confirm that stains form at low humidity. Chemical analysis shows that they contain iron particles and polymeric binder transferred from the MP tape. The chemical anchors in the binder used to grip the iron particles now react with the ferrite surface to create strong chemical bonds. At high humidity, a thin layer of iron oxyhydroxide forms on the surface of the ferrite. This soft material increases the wear rate and so reduces the amount of stain present on the heads.