Abstract: A composite type magnetic head core slider including a slider body and a core chip, wherein a slot is formed in the slider body such that the slot is open in an end face of the slider body and located within a width of a central recessed portion between two parallel air-bearing portions formed on a surface of the slider body which is to face a magnetic disk, or within a width of an outer recessed portion disposed on one side of one of the air-bearing portions, which one side is remote from the central recessed portion. The core chip is fixed in the slot such that an upper end portion of the core chip protrudes above a surface of the central or outer recessed portion, and the protruding upper end portion of the core chip is subjected to an operation to form a track portion having a magnetic gap.

Abstract: An etching method for etching a sendust film formed on a substrate is disclosed. In this method, a mixture of acid solutions of nitric acid and hydrochloric acid is used as an etching liquid. The etching is desirably effected while the sendust film is directly or indirectly held in electrical connection with a ferrite member, with an area of a portion of the ferrite member which contacts the etching liquid being twice to twelve times a total area of etched portions of the sendust film. Also disclosed is a method for pattern-etching a sendust film, and a chromium base film formed between the sendust film and a substrate, which includes the steps of: (a) etching the sendust film to form a predetermined sendust pattern; and (b) etching the chromium base film to form a chromium pattern which conforms to the predetermined sendust pattern, such that the chromium base film is directly or indirectly held in electrical connection with a chromium bulk.