Pole tip recession in linear tape heads: Measurement technique and influence of head materials, tape speed and tape tension

Abstract

Pole tip recession (PTR) in linear tape heads causes an increase in spacing and consequently an increase in signal loss. In this study, PTR in linear tape drives is analysed. Functional drive tests are conducted using thin-film Al2O3-TiC and Ni-Zn ferrite heads sliding against metal particle tape. Atomic force microscopy is used to measure PTR and the recession of the overcoat material used in the construction of the head. In measuring PTR, care must be taken in correctly orienting the stand-alone atomic force microscope tip with respect to the head sample. Care must also be taken in post-processing the raw stand-alone atomic force microscopy data. Based on PTR data with Al2O3-TiC and Ni-Zn ferrite heads, no significant differences exist in the PTR of Al2O3-TiC heads compared with Ni-Zn ferrite heads. In the case of the Ni-Zn ferrite head, the softer Ni-Zn ferrite substrate has mechanical properties close to those of the poles, suggesting that PTR growth should be low. However, additional third-body wear particles from the ferrite substrate result in additional pole tip wear. No significant difference is seen in the wear of Co-Zr-Ta poles and Ni-Fe poles, as they have comparable mechanical properties. No strong conclusion may be drawn about the effect of tape speed on PTR. An increase in tape tension leads to an increase in PTR. This is a result of an increase in the normal force, which causes an increase in the abrasive wear. An increase in interface contamination also leads to an increase in PTR.