Off-track capability of a pole trimmed thin film head

In order to improve off-track capability and thus to achieve higher track density, both sides of the upper and lower pole tips of inductive thin film heads were trimmed to become nearly the same in width, through photolithography and ion milling processes at the air bearing surface. The off-track capability improvement attained by the pole trimming was experimentally estimated by performing off-track profile evaluation and “747 curve” measurement. The difference between the effective track width and the upper pole width, which represents the amount of track side writing and side crosstalk effect, was found to be reduced to 68% of that seen in conventional thin film heads. It was also found that the track interval can be squeezed by as much as 1.0 μm more than conventional thin film heads, based on the 747 curve comparison