Wire memory technology in Japan

Abstract

Manufacturing techniques of plated wires have rapidly developed and uniform characteristics and stable reproductivity, even for long wires, have been accomplished. Magnetic films used in Japan are typically from three to five multilayered in order to broaden operating margins and for better control of the characteristics. The method of fabricating word lines with keepers by automatic weaving machines is one of the unique techniques of Japan. The fabrication technique used in forming digit lines into a laminated cable eliminates connections between the planes and reduces the assembling cost. Adhesion type planes, which have several spare bits, are suitable for manufacturing large capacity modules at low cost. Several improvements are also employed in the tunnel structure. FSM is concentrated upon because of its miniaturization and combination with the IC techniques. The total number of planes and memory systems produced and sold in Japan has reached 3 × 108bits in capacity. And the annual production quantity is nearly 10% of core memories. Further promotion of use for wire memories is expected by realizing the following: 1) improvements of bit density (more than 500 bit/cm2); 2) stable connection at low cost; 3) standarizations of wire, plane, and IC for read-write circuits; and 4) widespread and closely knit exchange of technical information among wire people.