An Approach Towards Batch Fabricated Ferrite Memory Planes

This paper describes a technique for the batch fabrication of ferrite memory arrays in which wire, previously coated with a thermoplastic, is formed into two orthogonally disposed sets of parallel wires. These grids are oriented between opposing molds having matched grooves filled with a fluid mixture of ferrite powder and thermosetting resin, in such a manner that one set of parallel wires coincides with the groove axes. After suitable curing this structure is released and heat treated to pyrolyze the organic materials and sinter the ferrite. A yield study on 108 memory arrays produced in this manner resulted in a yield of 72.2% on pulse testing under simulated operating conditions and an over-all process yield of 36.1%. The paper concludes with a tabulation of electrical characteristics of the arrays and a brief discussion of the applicability of the technology to various modes of operation and its potential for high-speed (250 nsec magnetic cycle time) operation.