GB1494840A - Method for producing multiple-track magnetic heads - Google Patents

Abstract

1494840 Multiple-track magnetic heads NIPPON GAISHI KK 17 Feb 1975 [23 Feb 1974] 6561/75 Heading G5R In the manufacture of multi-track magnetic heads a shield plate 10 is located between the magnetic polepieces corresponding to two adjacent tracks by coating 9 a magnetic ferrite plate 8, Fig. 5, with at least one material selected from glass, silica, alumina, zirconia and titania to form the shield plate 10, the plate 10 having a thickness only slightly less than the distance between the adjacent polepieces between which the shield plate 10 is then inserted, then setting pieces of glass 11 on each of the boundaries between the shield plate and the adjacent polepieces, the glass 11 having a melting point so low as not to adversely affect the polepieces when the glass 11 melts, and then melting the glass 11 to bond the shield plate 10 between the adjacent polepieces by capillary action. The polepieces are produced by glass bonding ferrite core elements 1, Fig. 1, together to form a front core block (4), Fig. 2 (not shown), the back region of which is then grooved 6 for receiving the shield plates 10. The elements 1, 2 may be bonded together by heating under pressure after applying a glass paste, of glass powder and a binder, all over opposed surfaces la, 2a or preferably in the form of a stripe 1b along a centreline of one or both of surfaces 1a, 2a. Grooves 1c, 2c form a channel (5), Fig. 2 to accommodate surplus glass. A desired gap length may be obtained by application of appropriate pressure during reheating of the bonded core block (4). The ferrite plates 8 may be coated by heating after application of a past consisting of a powder, of glass, silica, alumina, zirconia and/or titania, and a binder. The plates 8 may alternatively be coated by a vapour deposition method, e.g. by a method in which a gas mixture of SiH 4 , N 2 O and an inert gas such as N 2 is subjected to a high frequency discharge to apply a silica coating. The glass used for bonding together elements 1, 2 and for coating plates 8 preferably has a thermal expansion coefficient and a hardness close to those of the ferrite of parts 1, 2, 8, the glass pieces 11 may have a similar expansion coefficient but greater or smaller hardness. After bonding plates 10 in grooves 6, the assembly is ground to expose plates 10 at the working face and then a coil-carrying back core block is applied.