Method of making a magnetic core of a magnetic thin film head

In a method of making a magnetic core segment of a magnetic thin film head which comprises a non-magnetic substrate, a lower magnetic layer deposited on the non-magnetic substrate to form a lower magnetic core segment, a magnetic gap layer overlying the lower magnetic layer, at least two insulating layers overlying the magnetic gap layer, at least one electrically conductive layer interposed between the insulating layers, and an upper magnetic layer overlying the insulating layers to form an upper magnetic core segment, the improvement comprising the steps of:

• (a) depositing a magnetically soft layer on a surface to be electroplated, thereby forming an electroplated layer made of a metal alloy;
• (b) with said surface temporarily used as an anode anodically dissolving a surface region of said electroplated layer opposite to said surface, thereby forming a modified layer which is different at least in composition from said magnetically soft layer and which is not magnetically soft;
• (c) cyclically repeating the steps (a) and (b) a plurality of times to form at least one of said lower and upper magnetic core segments as a multi-layered structure comprising a plurality of magnetically soft layers and a corresponding number of modified layers alternating with each other thereby magnetostatically separating each of said magnetically soft layers.