Fabrication of multi-turn thin film head

A new fabrication method has been developed for multi-turn thin film heads. In this method, a multi-turn coil is formed by piling two layers of flat surfaced bifilar spiral coils. A bevel-etching technique has been developed to form the flat surface of the bifilar coil. A 9-turn, 18-track thin film head has been fabricated and tested on the conventional particulate disk. The read efficiency was 88% and the MMF required for 30 dB of overwrite was 0.32AT.