US3584130A - Substrate for mounting filaments in close-spaced parallel array - Google Patents

Abstract

A substrate for mounting filaments in close, accurately spaced, parallel array. A soft wire is carefully wound upon a mandrel with successive turns tightly packed against each other. Replicas of plastic or other materials are made of the surface formed by the wire. The filaments to be supported are laid in the grooves in the replicas.

Description

United States Patent [72] Inventor Harry J. Green, Jr.

Rochester, N.Y.

[21] Appl. No. 872,429

[22] Filed Oct. 29, 1969 [45] Patented June 8, 1971 [73] Assignee Nemonic Data Systems, Inc.

Denver, Colo.

Continuation of application Ser. No. 625,771, Mar. 24, 1967, now abandoned.

[54] SUBSTRATE FOR MOUNTING FILAMENTS 1N CLOSE-SPACED PARALLEL ARRAY 1 Claim, 7 Drawing Figs.

[52] U.S.Cl. 174/1, 161/123, 249/175, 264/220, 264/227, 340]?74 [51] Int. Cl. Gllc 5/04,

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Primary Examiner-Laramie E. Askin Attorney-Hoffman Stone ABSTRACT: A substrate for mounting filaments in close, accurately spaced, parallel array. A soft wire is carefully wound upon a mandrel with successive turns tightly packed against each other. Replicas of plastic or other materials are made of the surface formed by the wire. The filaments to be supported are laid in the grooves in the replicas.

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,QBYWSIAM ATTORNEY SUBSTRATE FOR MOUNTING FILAMENTS IN CLOSE- SPACED PARALLEL ARRAY BRIEF SUMMARY OF THE INVENTION This application is a continuation of the U.S. Pat. application Ser. No. 625,771, filed on Mar. 24, 1967 for Harry J. Green, Jr. entitled, Substrate For Mounting Filament In Close-Spaced Parallel Array," now abandoned.

There has been much recent interest in thin film magnetic memory devices of the type including filaments such as wires coated with thin films of magnetic material, typically applied by electrolysis or evaporation in vacuuo. The filaments are typically about 0.004 to 0.005 inch in diameter, and the thin film magnetic materiai is typically about 1 micron thick. The output signals produced in the operation of devices of this type are relatively small, typically on the order of a few millivolts, and it is important to achieve a high degree of uniformity in the spacings between successive wires when they are arranged in parallel array to form a matrix, otherwise variations in coupling between adjacent wires at different points along their lengths may tend to introduce errors into the system. Also, to minimize certain deleterious effects due to magnetostriction, it is desirable to provide firm support for the wires that carry the thin film magnetic material. Finally in the interest of space conservation, it is desirable to space the wires as closely together as possible.

Briefly, a substrate in accordance with the invention comprises a replica of the surface formed by winding a soft metal wire upon a fiat mandrel with each successive reach of the wire straightened by stretching and carefully forced against the preceding reach. A master mold is made from the mandrel, and the substrates are cast in the master mold. Alternatively, more complex replication techniques may be used such as, for example, techniques applied in the production of phonograph records and of optical diffration gratings. As many of the replicas as desired may be secured together to form'a relatively large substrate. Typically, the replica is made of an insulating material such as a thermosetting resin, and an electrically conductive plate may be molded into the replica to provide an electrical ground plane.

DETAILED DESCRIPTION A presently preferred embodiment of the invention will now be described in detail in connection with the accompanying drawing, wherein:

FIG. 1 is a fragmentary isometric view of a mandrel partly wound with wire, indicating an initial step in the manufacture of a substrate according to the invention;

FIG. 2 is a cross section taken along the line 2-2 of FIG. 1;

FIG. 3 is a cross-sectional view of a mold according to the invention, illustrating casting of a substrate;

FIG. 4 is a partly schematic diagram in isometric form of the assembly of individual units according to the invention to form a relatively large substrate;

FIG. 5 is a perspective view on a larger scale than FIG. 4 of a support according to the invention;

FIG. 6 is a cross-sectional view of a support generally similar to the one shown in FIG. 5, but without a conductive ground plane; and

FIG. 7 is a cross-sectional view of the support shown in FIG.

form of a replica of a master mold 12, which is made by winding a soft wire 14 upon a mandrel 16, the significant surface 18 of which has been carefully finished to a high degree of flatness. To insure that the wire 14 lies flat upon the mandrel, the edges of the mandrel around which the wire is turned are rounded over a relatively long radius such that the wire will readily accept the curvature. The wire 14, which may be, for example, of copper, is straightened by stretching either just prior to winding or as it is wound. The winding is carefully done, and each turn of the wire is forced againstthe recedin one so that it lies "I abutting engagement with it. A ter WIII ing, the mandrel with the wire 14 upon it is carefully inspected to insure that the wires are straight and true, free of foreign matter, and lie flat upon the mandrel. If desired, the mandrel may be first. coated with a film of an adhesive material to secure the wire 14 firmly upon it. Molds 20 are then made by casting upon the mandrel. The molds 20 may be made of any desired casting material such as certain silicone compositions, many of which have been specially developed for use in dentistry, and which are capable of forming accurate negative images of the surface formed by the wire 14.

The molds 20 are then used to produce replicas 10 of the original master mold 12. The replicas 10 are typically cast of an insulating thermosetting resin selected from among those having good dimensional stability. For certain uses, it is desired to provide a sheet of conductive material, called a ground plane, closely adjacent to, but insulated from, the wires of the magnetic memory. For this purpose, after the mold 20 is partly filled with the insulating material that is used to form the replica 10, a sheet 22 of conductive material is placed in the mold and pushed down until it comes into contact with and rests on the lands 24 of the mold. The balance of the mold is then filled with the insulating casting material, which is then hardened to form a rigid substrate for the wires of the magnetic memory or any other filaments.

The replicas I0 can readily be made with a high degree of accuracy, that is, with very small deviations from the shapes and dimensions of the surface of the wire 14 on the mandrel. For all practical purposes, the replicas are exact copies of the surface. If reasonable care is exercised in winding the wire 14 upon the mandrel 12, a large number of individual replicas 10 may readily be arrayed in uniform registration to form an overall memory plane of any desired size. Each replica 10 is identical to the next one, and alignment and registration problems are, therefore, minimized.

Another advantage in the practice of the invention relates to the cross-sectional shape of the grooves. The grooves are generally V-shaped in cross section so that the wires, or other filaments laid in them are urged toward and held in centered alignment with the grooves with a high degree of uniformity and precision.

Iclaim:

l. A striated support for electrically conductive filaments or the like comprising a body of stiff insulating material having a striated surface of similar shape to a surface formed by laying down successive lengths of a round wire in straight abutting relationship upon a flat support and a sheet of a conductive material molded integrally within said body lying immediately beneath and substantially coextensive with the striations to constitute a ground plane.

Claims (1)

1. A striated support for electrically conductive filaments or the like comprising a body of stiff insulating material having a striated surface of similar shape to a surface formed by laying down successive lengths of a round wire in straight abutting relationship upon a flat support, and a sheet of a conductive material molded integrally within said body lying immediately beneath and substantially coextensive with the striations to constitute a ground plane.

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