Patent GB-1293897-A (GB)
Title: Method for producing a matrix memory device of high bit density
IPC: G11C5/02
Filed: 1970-01-27
Abstract: 1293897 Magnetic storage arrangements KOKUSAI DENSHIN DENWA KK 27 Jan 1970 [4 Feb 1969 (3)] 3852/70 Heading H3B A matrix store comprises a set of parallel strip conductors 5, Fig. 1A, each coated wholly or at spaced intervals with two thin magnetic films 4, 4A which together form a closed magnetic path about the conductor, the conductors so coated being located between and orthogonal to first and second sets of parallel strip conductors 2 carried by a respective insulating sheet 1, the coated conductors being secured to the first and second conductor sets by adhesive 3. To manufacture the store, an etch resistive material 8, Figs. 3A-3G, is applied in strips to a conductive, e.g. copper, plate 5 so that grooves are formed in a subsequent etching process. A thin magnetic film 4 is then deposited on to the grooved surface and the assembly then secured by an adhesive layer 3 to parallel strip conductors 2 carried by an insulating sheet 1. Chemical or electrical etching is then used to remove portions of the plate 5 until only conductive strips 5 with trough-like thin magnetic film coatings remain. Application of a further layer of thin magnetic film 4a completes a closed magnetic path about the strip conductors 5. The store is completed by using adhesive 3 to adhere a further set of parallel strip conductors 2 and an insulating sheet 1. A modified construction, Figs. 4A-4D, commences with a substrate 1 having sequential layers of parallel strip conductors 2, adhesive 3, thin magnetic film 4 and a conductive plate 5, the pattern of conductive strips each with an underlying thin magnetic film layer being formed by etching regions left exposed by an etch resistant coating 8. Closed magnetic paths are formed by coating the exposed surfaces of the strips 4, 5 with magnetic thin film 4a, after which a further set of parallel strip conductors 2 and insulating sheet 1 are secured by an adhesive 3. An alternative manufacturing process utilizes a glass plate 6, Figs. 7A-7D, having a silvered layer 7 and a conductor layer 5 bearing on resist pattern 8. A thin magnetic film 4 is coated in the conductive layer not covered by the pattern 8, after which this pattern is removed, and the layers 7, 5 and 4 transferred on to an insulating sheet and conductive strip assembly 1, 2 and secured by an adhesive layer 3. A resist pattern 8a is used to permit etch removal of those parts of layers 7 and 5 not above a film region 4 and leave a parallel pattern of conductive strips which are then coated with thin magnetic film 4a. A glass substrate is used in a further method, Figs. 8A-8D, which is coated initially with a thin magnetic film 4, a conductive layer 5 and a resist pattern 8. Strip conductors are formed by etching and subsequently coating with thin magnetic film 4a. The completed assembly includes the glass plate 6 between the two insulating sheets 1. Upper and lower strip conductors 2 have their ends relatively offset to provide staggered edge terminal portions, Fig. 9B, and the magnetic coatings 4, 4a need only be applied at spaced positions along the conductive strips 5, Fig. 2C.