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

Thin Film recording heads are fabricated either by "dry" process, or " wet " process. In the dry process, sputtering and ion etching are used. In the case of wet processing, a combination of dry process, phololithography patterning and electrochemical deposition are employed. For most manufacturers, Permalloy layers in the thin film inductive heads are deposited by electroplating. The composition uniformity of the Permalloy over the flat and stepped portion of the head plays an important role in the read/write characteristics and magnetic performance of thin film heads. To increase magnetic recording density, one requires the reduction or the track width or a magnetic head. How narrow one can plate Permalloy and still obtain uniform composition? In this paper we have studied the composition variation or the electroplated Permalloy films with electron microprobe, (EPMA/WDS). The electroplating was carried out in the system similar to the one described in reference 6. The composition variation of the upper magnetic layer from pole tip to yoke was studied as a function of both track width and topography. The track width was varied from 5 to 26 microns and the topography was varied up to 20 microns. Keeping the topography constant at 17 microns and varying the pole tip track width of plated Permalloy from 6 to 26 microns, the apparent composition difference between pole lip and yoke decreased from 1% to 0.4%.