The effect of track width and topography on composition uniformity of electroplated Permalloy in thin film heads

The composition difference of the plated Permalloy in thin-film heads from pole tip to yoke was studied as a function of the track width and topography. The variation of the track width ranged from 5 to 26 μm and that of the topographical height ranged from 0 to 20 μm. Results show that there was no composition difference for flat structures. However, as the topographical height increased from 0 to 20 μm, the composition difference between the yoke and pole tip changed from 0 to 0.5%. In all cases, it was found that higher topographical areas are Fe-rich. This difference was explained by the diffusion mechanism as opposed to a current crowding model. It was concluded that electroplating can be used to deposit Permalloy in track widths as narrow as 5 μm without substantial degradation in composition uniformity