US3204329A - Method of manufacturing magnetic core assemblies - Google Patents

Description

Sept. 7, 1965 swEENE 3,204,329

METHOD OF MANUFACTURING MAGNETIC CORE ASSEMBLIES Filed Nov. 13, 1961 2 Sheets-Sheet 1 INVENTOR. JosE PH P. SWEENEY Sept. 7, 1965 J. P. SWEENEY 3,204,329

METHOD OF MANUFACTURING MAGNETIC CORE ASSEMBLIES Filed Nov. 13, 1961 2 Sheets-Sheet 2 ..@.@.@.@.@.@@.@@.@.@@@.@.@.@@QQQL@IQEfi- 8M i an 1 1?]??? INVENTOR. Jose? P. wseuw 3,204,329 METHOD OF MANUFAETURING MAGNETIC CORE ASSEMBLIES Joseph P. Sweeney, Harrisburg, Pa, assignor to AMP Incorporated, Harrisburg, Pa. Filed Nov. 13, 1961, Ser. No. 151,797 Claims. (Cl. 29-15556) This invention relates to magnetic core assembly means and method.

A primary object of this invention is to provide a magnetic core assembly and a method of assembly resulting in an economy of production of magnetic core devices.

Anotherobject of invention is to provide a magnetic core package having characteristics which accommodate a continuous assembly procedure including core testing and wiring.

A specific object of invention is to provide a method of assembly of magnetic core devices wherein individual handling of cores during all phases of production is avoided.

A further object of this invention is to provide a universal core assembly capable of use in a broad range of bit lengths and package configurations.

A still further object of invention is to provide a core assembly wherein the cores and core conductors are so arranged that various design applications may be accommodated without additional engineering of core and winding placement or proximity.

Another object of invention is to provide a magnetic core assembly adaptable to long bit lengths in a single unbroken array of cores and windings.

Still another object of invention is to provide a core assembly wherein the ratio of active components to packaging components is minimized.

An additional object of invention is to provide a core and winding assembly resistant to shock and vibration without the use of potting material.

The general trend toward miniaturization of electronic assemblies relative to equipment weight, space and power requirements has resulted in production and reliability problems which substantially offset the advantages gained through the use of solid state devices in general and magnetic core devices in particular. Moreover, the various efforts to counter the complexities of sub-miniaturized manufacture have developed packaging techniques which do not lend themselves to economic production and which produce units inherently limited as to the different space and configuration requirements of the equipment served by such devices. The present invention contemplates a magnetic core mounting member having characteristics which eliminate, to a large extent, the production problems of prior art devices and which provide an end product of broad utility.

The basic problem underlying both production and product in magnetic core devices is that large numbers of relatively small components must be combined in a manner whereby component operation will not be hampered by field interaction between cores and windings. While much work has been done with magnetic cores, the engineering of winding impedance and core and winding proximity is, as yet, empirical and slight variations frequently effect substantial and unpredictable changes in operation. The present invention features a core and winding arrangement wherein a variety of equipment space and configuration specifications may be accommodated without substantially changing core spacing and winding length.

The magnetic core assemblies of the prior art comprising rigid panel or frame members carrying a given number of cores are representative of a design compromise between the factors of production economy, including ac- United States Patent 0 cess to cores for wiring and the factors of end product utility including unit size, weight, shape and function capability. The significant result of this compromise is that prior art devices do not satisfy either of these requirements. As an example, the use of rigid construction for core mounting members requires that the separate core units be individually handled and that means be provided to move such units between the various stages of production. As a further example, the use of rigid core mounting member requires that ideally all cores be individualy pre-tested prior to the initial assembly step. The present invention employs a flexible tape-like component mounting members which may be continuously moved through all stages of magnetic core device production including core testing. The core mounting member of the invention thus serves the dual function of moving the cores through the complete manufacturing cycle, and as a core mounting means for the finished product.

The use of core mounting members of fixed dimensions, as in all known prior art devices, has the result that when employed with equipment of limited capability, a portion of the unit is unused or wasted and when employed with equipment of extensive capability, numerous units must be mechanically and electrically connected together. The present invention features a core-tape assembly which may be cut to the exact length needed by equipment served.

An additional advantage of assembly of the present invention over known devices is that the ratio of active components such as, cores and conductors to inactive components such as supporting members and potting material is minimized from the standpoint of dimension, weight and cost. One embodiment of the present invention utilizes a tape sandwich construction which eliminates the use of potting material without increasing the possibility of core and winding misalignment to vibration and shock.

Other objects and attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings in which there is shown and described an illustrative embodiment of the inven tion; it is to be understood, however, that this embodiment is not intended to be exhaustive nor limiting of the invention but is given for purposes of illustration in order that others skilled in the art may fully understand the invention and the principles thereof and the manner of applying it in practical use so that they may modify it in various forms, each as may be best suited to the conditions of a particular use.

In the drawings:

FIGURE 1 is a schematic flow diagram of the method of the invention showing the various necessary and possible steps of a production cycle.

FIGURE 2 is a plan view of one embodiment of the magnetic core assembly of the invention prior to wiring.

FIGURE 3 is an enlarged section of the assembly of FIGURE 2 taken along lines 3-3.

FIGURE 4 is a plan view of the core-tape assembly partially wired in a manner to perform a shift register function.

FIGURES 5 and 6 show two exemplary embodiments of the assembly of the invention as employed in core packages.

As heretofore mentioned, the present invention includes a magnetic core assembly means and method of assembly. The following description will treat the method of assembly initially and the assembly and its various embodiment thereafter.

Referring particularly to FIGURE 1, a plurality of successive assembly steps are shown beginning with the tape supply and ending with either assembly storage or assembly cutting and storage. As will be apparent from the following description, certain of the steps shown may be omitted or may be performed in a non-continuous man ner with interim storage of the core-tape member between stages. The element 20 represents the tape member of the invention and comprises a thin flexible material having insulating and non-magnetizable qualities. Additionally, the tape member should be readily pierceable without splitting or fracturing. Paper, Mylar, (polyethylene terephthallate resin), acetate, and glass or fiber tapes are typical materials having the foregoing characteristics.

The method of the invention contemplates a continuous supply of tape provided by means such as a reel or spool 22 motivated or drawn through the various method steps by means such as sprockets 40 driven at a constant speed by any suitable means. Immediately following tape supply 22 is adhesive supply 24 which may be by roller, brush or spray depending upon the adhesive employed. As an example, if contact cement is employed, the unit 24 may comprise a roller extending the full width of the tape member so as to apply a thin coating thereon. Alternatively, if epoxy cement is used, a narrow pressure fed brush may be employed as element 24 to apply a strip or beading of adhesive along the tape member centerline. The amount of adhesive employed should be only enough to assure that the cores will remain aligned on the tape until after the core wiring step, since the core wiring being inserted through the tape will serve to hold the cores in position thereafter.

Following the application of adhesive, the tape member 20 is moved past core supply 26 and cores are deposited on the tape member and secured thereto by the adhesive coating.

As shown in FIGURE 4, the tape member 116 may include sprocket slots 117 by which the tape may be driven or propelled through the various production steps. The slots 117 additionally serve to index the tape for proper core placement. The approximate minimum spacing between cores should be 15 mils edge to edge. For example, when employing General Ceramics No. F1243- 5209, cores 196 mils Wide and of a configuration as shown in FIGURE 4, the center to center spacing would be at least 211 mils. When using standard 80 mil outside diameter toroidal cores, this distance would be at least 95 mils. The proper initial placement of the cores on the tape member will facilitate the further steps of production and will assure proper core and winding proximity in the end product.

The core test step follows core mounting and includes a procedure wherein the cores are tested by measuring the core switching threshold. This is accomplished by applying a magnetomotive force to the core by means of an input conductor or conductor inserted through the major aperture thereof carrying a current sufiicient to first set the core; thereafter reversing the current to reset the core while measuring the voltage induced in an output conductor threading the same aperture. The currents employed should be of a quality and quantity to accomplish set and reset in a standard acceptable core with an induced voltage in the output conductor between maximum and minimum limits. As an example, when using multi-aperture cores similar to those shown in FIGURE 4, known as General Ceramics Cores F12435209, the applied set pulses should be of a trapezoidal shape of an approximately 0.3 micro-second rise and fall time, 3 micro-second duration and approximately 270 milliampere amplitude. This input current pulse should produce, on the output conductor, a voltage not more than 25 microvolts. This should be followed by a similar set pulse of approximately 330 milliamperes amplitude with an output voltage of not less than 25 millivolts. Any number of voltage responsive circuits may be employed to present a visual or audible signal indicating the presence of a defective core. One simplified circuit for accomplishing this could include two switch inserted triode driven relays set to operate respectively, responsive to core output voltage above or below the standard voltage.

With the core-tape assembly of the invention, the core test may be performed by needle members connected to the input and output conductors heretofore mentioned and arranged to penetrate or pierce the tape through the major aperture of the core and cooperate with return circuit contacts for the conductors disposed on the underside of the tape member.

The numeral 32 represents core removal following any test indicating the presence of a defective core. It is contemplated that defective cores may be removed by blade or knife means arranged to slide between the core member and the tape. After removal of defective cores a second core supply 36 is provided to replace the removed cores with pre-tested cores. The number of cores removed and replaced represents a small percentage of the total number of cores use. In view of this, the adhesive material should have a setting time at least greater than the time required for the foregoing assembly steps.

After the step of core-resupply, the core-tape assembly may then be wired, as indicated schematically at 38, by needle means inserted through the core apertures and through the tape member with the various windings being applied in a desired pattern.

Referring now to the step indicated by numeral 50, an auxiliary tape member 53, supplied from a reel 54, may be applied over the tape 20, cores 27 and wiring 45. Tape member 53 is generally similar in construction to tape member 20, but of a lighter weight and thickness. The tape member 53 should be firmly pressed against the core-tape assembly so as to prevent core and winding movement. In addition to insulating the cores and Windings, the tape member 53 thus serves the function heretofore accomplished by the application of potting material.

As shown in FIGURE 1, the final step of the method of the invention consists of assembly storage as by reel member 60. Alternatively, and in large production runs, the core-tape assembly may be cut as indicated at 64 to predetermined bit lengths and stored in fiat sections 66, as shown.

As heretofore indicated, it is contemplated that the foregoing steps may be performed sequentially and continuously. It will be apparent that as a matter of convenience, individual combinations of steps could be performed with intermediate storage therebetween. Such intermediate storage would follow the step of core supply or any succeeding step thereafter.

The method of the invention may be performed by hand or by machine or alternatively, by various combinations of automatically or manually operated devices. The provision of the tape slots provides a means of control assuring accurate core spacing and thereby accurate positioning for the additional prouction steps.

In either event, the steps above described provide a unique method wherein magnetic core devices of various sizes and shapes may be economically and rapidly assem bled without individual handling of cores.

Turning now to the assembly of the invention, FIG- URE 2 represents a segment of the core-tape as it would appear after the step of core supply 26. It will be noted that in this embodiment a row of twenty multi-aperture cores 80, separated by a space 84, is positioned on one surface the tape member 82. The core arrangement in this embodiment is for a ten bit shift register and the spaces 84 provide a sufficient length of wiring (not shown) at each end of the core array to permit termination of the register conductors. For final use, the tape member 82 (after wiring) would be cut at lines 86 and the core-tape assembly therebetween would form a ten bit shift register package suitable for a variety of further packaging arrangements.

FIGURE 3 is included to show the disposition of components with core member bedded in adhesive 88 on tape member 82. As a matter of comparison, the ten-bit .5 register of FIGURE 2 occupies as little as one fiftieth the volume of prior known devices of the same capability. The tape member 82, as shown in FIGURE 3, comprises in one embodiment Mylar tape, 4 mils thick and 200 mils wide, as compared with a known prior art construction of epoxy glass sheet 63 mils thick and 900 mils wide.

Referring to FIGURE 4, there is shown a partially wired core-tape assembly, manufactured in accordance with the method of the invention. Referring to US. Patent No. 2,995,731 Wiring Arrangements for Shift Register Employing Magnetic Cores, it will be noted that the multi-aperture cores may be connected by continuous advance and prime windings. This technique is particularly useful when employed with the present invention since the advance and prime windings may be continuously threaded along the tape length in the manner indicated. The tape member 116 may comprise any of the tape constructions heretofore described. The conductor 118, which represents the drive common and negative prime winding, is threaded through the tape 116 and the receiving minor apertures of the cores. Conductors 120 and 122 are similarly threaded through tape 116 and the cores and represent respectively ADVANCE E to O and O to E in the manner explained in Patent No. 2,995,731. With the addition of input an output windings to the receiving aperture and transmitting aperture of the core 126 and 124 and coupling or transfer windings between cores as described in Patent No. 2,995,731, the core-tape assembly becomes a six (6) bit shift register, considerably smaller and lighter than prior art devices of the same bit capability.

It is to be understood that in instances wherein large production runs of standardized core assembly lengths are made, the tape may be pre-punched to provide holes matching the major and minor aperture configurations of the particular cores employed. Additionally, this practice may be desirable in situations wherein the number of minor aperture turns makes it difficult to thread through the tape. It will be apparent that other wiring arrangements can be utilized with the core-tape assembly for different magnetic circuit functions.

FIGURES 5 and 6 show various applications of the present invention to difierent core arrangements. In FIG- URE 5 a wired core-tape assembly having the auxiliary tape member 130, as heretofore described, is wound on a rectangular support 132 in overlapping fashion. A unit of this type may be readily accommodated for serial to serial, serial to parallel, parallel to serial or parallel to parallel operation be individual core connections connected as each layer of core-tape is wrapped on the support 132. The individual connection may be made directly to terminals 134 from each core-tape layer. The entire assembly may, if desired, be potted or alternatively wrapped with a single insulating tape cover.

FIGURE 6 shows a further embodiment of the invention wherein the tape member 110 is comprised of glass cloth. In this construction, the cloth tape, following mounting, testing and wiring, is treated with a thin coating of epoxy or phenolic resin and placed on a mold of desired shape. After the resin has set, the assembly may then be removed and utilized without additional support. As will be apparent, the setting of the resin will additionally prevent core and conductor movement due to the threading of the core conductor 112 through the cloth material.

Changes in construction will occur to those skilled in the art and various apparently diflferent modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only. The actual scope of the in vention is intended to be defined in the following claims when viewed in their proper perspective against the prior art.

I claim:

1. A method of manufacturing magnetic core assemblies including the steps of moving a flexible tape member through a series of production stages; individually securing a plurality of magnetic cores having at least one aperture therein to said flexible tape member in a pattern of common orientation and spacing according to indicia thereon; individually testing each said core by inserting an input conductor and an output conductor through the said core aperture, applying predetermined currents to said input conductor and measuring the core voltage induced in said output conductor against a reference voltage; removing each core having an output voltage below or above said reference voltage and replacing each removed core with a pre-tested core to form a continuous series of cores; wiring the said series cores by inserting conductors through an aperture therein and through the said tape member in a pattern to effect a desired circuit function.

2. A method of assembling magnetic core devices including moving a length of flexible tape through a plurality of production steps comprising applying an adhesive to said tape member and applying a series of magnetic cores in a pattern of common spacing and orientation to said adhesive; testing each of said cores by measuring the voltage output responsive to a standard reference current input; removing each core having an output voltage deviating from a standard reference voltage; replacing each removed core with a pretested core to form a continuous series of cores; wiring said series of cores by conductors threaded through each core and said tape member; and applying a second tape member over the wired core tape assembly.

3. A method of assembling magnetic core devices including the steps of moving a flexible tape member through a series of production stages; securing a plurality of magnetic cores to said flexible tape member in a pattern of common orientation and spacing relative to spaced slots therein; individually applying a given magnetomotive force to each said core and measuring the voltage produced by said core relative to a standard voltage; removing from said tape member each core having a nonstandard voltage output; replacing each removed core with a pre-tested core to form a continuous series of cores; inserting a number of different conductors through said eries of cores and said tape member; and storing the wired core-tape assembly in a single length.

4. A method of assembling magnetic core devices including the steps of moving a thin flexible tape member through a series of production stages; individually securing a plurality of magnetic cores to said flexible tape member in a pattern of common spacing and orientation; testing each of said cores by measuring the core switching threshold, removing those of said tested cores having a switching threshold above or below a desired value and replacing each removed core by a pre-tested core to form a continuous series of cores; inserting conductors through said series of cores and said tape in a predetermined pattern and cutting the wired core tape assembly into given lengths related to a given circuit function.

5. A method of manufacturing magnetic core assemblies including the steps of moving a flexible tape member through a series of assembly stages; coating the said thin flexible tape member with an adhesive material; depositing a series of apertured magnetic cores in a common spaced and oriented pattern on said tape member; individually testing each said core by measuring its switching threshold; removing each core having a nonstandard switching threshold and replacing each removed core with a pre-tested core to form a continuous series of cores; inserting conductors through each said core of said series in a predetermined pattern whereby each conductor intersects at least one core and a portion of the tape member adjacent such core; applying a further thin flexible tape member to the said series cores and conductors and to the said first tape member.

References Cited by the Examiner UNITED STATES PATENTS 5 7/39 Dahlgren.

8/57 Dewitz 336155 2/58 Jones.

5/59 Snyder 336-155 12/59 Damino 29-15557 10 Wohhnan.

Zack 29-155.57

Sweeney 340174 Wilk 29155.57 Clemons.

Singer 29-1555 X JOHN F. CAMPBELL, Primary Examiner.

JOHN F. BURNS, Examiner.

Claims (1)

1. A METHOD OF MANUFACTURING MAGNETIC CORE ASSEMBLIES INCLUDING THE STEPS OF MOVING A FLEXIBLE TAPE MEMBER THROUGH A SERIES OF PRODUCTION STAGES; INDIVIDUALLY SECURING A PLURALITY OF MAGNETIC CORES HAVING AT LEAST ONE APERTURE THEREIN TO SAID FLEXIBLE TAPE MEMBER IN A PATTERN OF COMMON ORIENTATION AND SPACING ACCORDING TO INDICIA THEREON; INDIVIDUALLY TESTING EACH SAID CORE BY INSERTING AN INPUT CONDUCTOR AND AN OUTPUT CONDUCTOR THROUGH THE SAID INPUT CONDUCTOR AND MEASURING THE CORE VOLTAGE INDUCED IN SAID INPUT CONDUCTOR AND MEASURING THE CORE VOLTAGE INDUCED IN SAID OUTPUT CONDUCTOR AGAINST A REFERENCE VOLTAGE; REMOVING EACH CORE HAVING AN OUTPUT VOLTAGE BELOW OR ABOVE SAID REFERENCE VOLTAGE AND REPLACING EACH REMOVED CORE WITH A PRE-TESTED CORE TO FORM A CONTINUOUS SERIES OF CORES; WIRING THE SAID SERIES CORES BY INSERTING CONDUCTORS THROUGH AN APERTURE THEREIN AND THROUGH THE

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