Improvements in or relating to multiple magnetic heads and to a method of making said heads

摘要

A magnetic read-write head, Fig. 1, is made up of two major sub-assemblies 1, 2 bonded to one another by epoxy resin, the sub-assemblies being previously built up with vitreous enamel. The assembly 2 includes an inter-gap screening system, members 12-13, in which the elements 12, 17, 18, 13 are of magnetic ferrite and the elements 14, 15, 16 are of silver. A similar arrangement of corresponding silver and ferrite elements are preferably used in the sub-assembly 1 to complete the screening. The read and write gaps 3, 4 are formed during the build-up of the sub-assembly 2 by capillary attraction of the enamel into gaps strengthed by non-magnetic ferrite members 11. A multiple-track embodiment, Fig. 2, is made by building up a stack as Fig. 1, but of greater width and then machining away the spaces 27, 32 into the elements 12, 13 to isolate the read and write cores. To build up the sub-assemblies, the ferrite elements are coated with a pulverized enamel suspension, which is dried and the elements heated to glaze them. The silver elements are coated with a suspension containing powdered silver and similarly heated. This results in a surface on the silver elements which is readily wetted by a subsequent application of enamel. All the glazed elements are again coated with the pulverized enamel suspension which is allowed to dry and the stack assembled and heated under pressure at 750 DEG C. The composition of the enamel is:- ..By ..weight .(a) SiO2.. .. .. ...16% .B2O3 .. .. .. ...14% .ZnO .. .. .. ...10% .PbO .. .. .. ...60% .(b) B2O3 .. .. .. ...18% .ZnO .. .. .. ...16% .PbO .. .. .. ...66% .or (c) SiO2 .. .. .. ...10% .B2O3 .. .. .. ...8% .ZnO .. .. .. ...16% .PbO .. .. .. ...66% The composition of the silver wetting agent is:- ..By ..weight .Ag .. .. .. ...93% .B2O3 .. .. .. ...7%