U.S. patent number 3,683,494 [Application Number 05/007,333] was granted by the patent office on 1972-08-15 for monolithic mad.
This patent grant is currently assigned to AMP Incorporated. Invention is credited to Harry Alvin Fox, Jr., William Baird Fritz, Emerson Marshall Reyner, II, Neil Harrison Sanders.
United States Patent |
3,683,494 |
Fritz , et al. |
August 15, 1972 |
**Please see images for:
( Certificate of Correction ) ** |
MONOLITHIC MAD
Abstract
A method of providing conductive windings on a magnetic core
wherein said windings are plated through small apertures in the
core and additional windings are plated through a larger
aperture.
Inventors: |
Fritz; William Baird
(Harrisburg, PA), Sanders; Neil Harrison (Carlisle, PA),
Reyner, II; Emerson Marshall (Harrisburg, PA), Fox, Jr.;
Harry Alvin (Palmyra, PA) |
Assignee: |
AMP Incorporated (Harrisburg,
PA)
|
Family
ID: |
26676849 |
Appl.
No.: |
05/007,333 |
Filed: |
January 15, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
601500 |
Dec 13, 1966 |
3506973 |
|
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|
Current U.S.
Class: |
29/604;
365/141 |
Current CPC
Class: |
H03K
19/166 (20130101); G11C 19/06 (20130101); Y10T
29/49069 (20150115) |
Current International
Class: |
G11C
19/06 (20060101); G11C 19/00 (20060101); H03K
19/02 (20060101); H03K 19/166 (20060101); H01f
007/06 () |
Field of
Search: |
;340/174CT,174MA
;29/604,602,625 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Campbell; John F.
Assistant Examiner: Hall; Carl E.
Parent Case Text
This application is a division of Ser. No. 601,500, filed Dec. 13,
1966, now U.S. Pat. No. 3,506,973.
Claims
What is claimed is:
1. A method of manufacturing wired core devices comprising the
steps of: forming a multiaperture magnetic core body as by molding
or casting of substantially unfired insulating magnetic material to
define a geometry including a major aperture and a plurality of
closely spaced minor apertures, firing said core body to provide
permanent square loop characteristics to the material thereof,
plating said body with a first layer of conductive material, minor
apertures to define conductive paths extending through said body
insulated each from the other only by material therebetween,
selectively removing portions of said first layer of conductive
material to define a first plurality of turns, covering said body
and said first plurality of turns with a layer of insulating
material, plating said layer of insulating material with a second
layer of conductive material, and selectively removing portions of
said second layer of conductive material to form a second plurality
of turns.
2. The method of claim 1 including the additional step of
selectively removing conductive material to define a drive circuit
for said device.
3. The device of claim 2 including as a further step connecting
said various turns to an input, output and drive circuit for
operating said device in controlled states of magnetization.
Description
This invention relates to magnetic core structures of the type
utilized in memory and logic devices and to methods for making such
structures.
A considerable effort has been made to utilize the storage and
logic capabilities of square loop magnetic material and much of the
electronic data processing apparatus in use today is made up of
core structures in the form of toroids, sheets, strips and other
core structures made of such material. The advantages of
intelligence storage without continuous drive power through a
device which has an infinite life have no doubt sponsored this. One
of the main limitations on core use has been the difficulty
encountered in wiring; applying necessary input, output and drive
windings. Drive power requirements and to a certain extent
frequency response and overall efficiency is related to the amount
of magnetic material employed to define a given core and generally
speaking, the smaller the core the better. The smallness has
aggravated the wiring problem which is directly related to physical
size. Even so, the largest usage of magnetic cores has been in
memory planes made up of small toroids. It is thought that this
usage is due to the fact that memory plane circuits generally
require only a single winding turn through a core body for input,
output and drive signals. The much lesser usage in the larger
multiaperture magnetic cores employed for logic purposes and for
providing relatively complex circuit functions is believed to be
due to the fact that these cores have circuits which include a
number of turns through the core apertures; making production
uneconomical. To illustrate the foregoing a comparison may be made
between a typical toroid memory device as is shown in U.S. Pat. No.
3,012,231 and a typical multiaperture logic device, as is shown in
U.S. Pat. No. 2,810,901.
Even with single turn circuits there has been a problem with
winding installation. That the problem is one which has existed for
some time is demonstrated in a number of patents: including U.S.
Pat. No. 2,911,627 which provides cores slotted to receive windings
and then faced over with magnetic material to close the air gap of
the slot; U.S. Pat. No. 2,910,675 which shows cores having
conductive pins fitted therethrough and terminated to printed
circuits for the purpose of adaption of core devices to automatic
production; U.S. Pat. No. 3,127,590 which features a core geometry
to facilitate straight through windings; and U.S. Pat. No.
3,129,494 which shows a method for automatically winding cores
including multiaperture cores with a plurality of turns. Still
other patents of interest to show the problem and an attempt at a
solution are U.S. Pat. No. 3,085,899 which discloses the concept of
molding up cores and windings in laminations with core material and
conductive material being placed between different steps of firing;
U.S. Pat. No. 2,882,519 which deals with obtaining desired winding
patterns on plate type structures; and U.S. Pat. No. 3,184,719
which deals with cores made through molded and printed circuit
techniques.
Some of the foregoing approaches are simple, but many of them are
complex. None of them, however, solve the problem of providing
multiple turns in a magnetic core structure without the need for
insertion of separate conductors through the same aperture. None of
them deal with the problem of placing turns having different
functions in a multiaperture core structure without having to
insulate between turns. In general, none of the prior art teaches
how to obtain a wired multiaperture core structure capable of
complex functions in a device which can be readily mass
produced.
It is an object of the invention to provide a means and method for
obtaining multiple winding turns through a core structure wherein
winding placement and insulation between turns having multiple
turns therethrough is inherently accommodated.
It is a further object of the invention to provide a simple and
inexpensive method and means for achieving multiple turn windings
in magnetic core structures for input, output or drive
purposes.
It is still a further object to provide a wired multiaperture core
device whereon windings may be formed through plating
procedures.
It is still another object of the invention to provide a core
structure for memory and logic applications which can be more
easily produced and which assures the proper placement of windings
by permitting an automated installation of windings on a core
structure.
It is yet another object to provide a core structure and circuit
which is more reliable than devices heretofore available.
The foregoing problems are overcome and the foregoing objectives
are attained by the invention through a magnetic core structure
wherein separate circuit windings turns are placed on a given core
through a series of small holes insulated each from the other only
by core material with a spacing which makes the various winding
turns link the same flux paths for certain purposes and different
flux paths for other purposes. Thus, when a given core geometry and
drive circuit calls for several turns which would be normally
threaded through a single common aperture to achieve a given
function, the invention contemplates a core structure having
separate small holes fitted with conductive pins or plated through
to be connected externally in a fashion to provide the desired
turns. In one aspect the invention contemplates molding and firing
a body of magnetic material with extremely small holes therein
grouped in a pattern sufficiently close together so as to simulate
a much larger aperture wound with multiple turns. In this version
the holes may be filled with solid conductive pins inserted
therethrough or by standard plating techniques which deposit
conductive material through such holes. Suitable linking conductive
material to complete the windings may be deposited directly on the
core material by plating techniques. Connector means joined in any
suitable fashion to the individual conductive paths may be utilized
to complete a connection to and from the circuit to provide the
desired input, output or transfer functions. In another aspect of
the invention it is contemplated that conductive wires or pins may
be placed in holes in a pressed or molded core structure to remain
therein as the core is fired; such pins then being interconnected
in a suitable fashion thereafter to provide desired winding turns
for use in a circuit.
In the drawings:
FIG. 1 is a schematic view of a core wound in accordance with an
accepted wiring scheme for input, transfer and output from a core
device (enlarged approximately five times actual size);
FIG. 2 is a plan view of a core having the same function as that
shown in FIG. 1, but made in accordance with the invention in one
aspect thereof;
FIG. 3 is a perspective of the core of FIG. 2;
FIG. 4 is a section taken along lines 4--4 of FIG. 3;
FIG. 5 is a plan view of a corner of the core of FIGS. 2-4
(enlarged even further) showing the details of the positions for
turn placement;
FIGS. 6-8 are perspectives of a corner of the core of FIGS. 2-5
showing various turns and an associated flux distribution to
explain the invention;
FIGS. 9 and 10 are plan views showing another core structure having
windings and turns plated thereon to provide a completed two bit
register; and
FIG. 11 is a section through lines 11--11 of FIG. 10.
Turning now to FIG. 1, there is shown a core structure which has
been used in a number of commercial applications. The structure is
wound in what is now a standard manner in accordance with a circuit
which is believed to offer perhaps the best range of operation for
multiaperture devices. This type of circuit is termed MAD-R for
Multi-Aperture Device - Resistance, and is disclosed in detail in
U.S. Pat. No. 3,125,747 to D. R. Bennion, granted Mar. 17, 1964,
and in U.S. Pat. No. 2,995,731 to J. P. Sweeney, granted Aug. 8,
1961. The exact core structure and circuit is described in detail
in U.S. application Ser. No. 305,780, in the name of Nitzan et
al.
Cores of the type used in such circuits are typically made of a
square loop ferrite material which is first pressed into the
desired geometry and then fired at relatively high temperature.
Most of the materials have insulating qualities. Prior to firing it
is a standard practice to utilize a binder which is burned out
during firing to leave the ferrite material having square loop
characteristics. Considerable shrinkage (20 or 30 percent) occurs
during firing and cooling of the formed core geometry. The
significance of these factors will be made apparent
hereinafter.
The core shown as 10 includes a pair of major apertures 12 and 14,
each placed in the body of magnetic material to define separate bit
positions. In each half surrounding a major aperture there is a
minor aperture such as 16, shown in the left half, which may be
employed as an input aperture. Also in the left half is a slightly
larger minor aperture shown as 18, which may be used as an output
aperture. The minor apertures 20 and 22 in the right half of the
core structure 10 have similar functions. The minor apertures of
the core define legs of magnetic material which permit
multiaperture magnetic core operation including diodeless transfer
and nondestructive readout, generally, and MAD-R operation,
specifically. The core 10 is shown wound by windings including a
coupling loop 24 linking the left core half to the right core half
to transfer information stored in the left core half to the right
core half. The coupling loop 24 is made to link the transmitter
aperture 18 by two turns and the aperture 20 by one turn. This
difference in turns is to achieve a sufficient gain to overcome the
losses inherent in the device. Further included is an input winding
26 linking the input aperture 16 and an output winding linking the
transmitter aperture 22. The input winding 26 has one turn and the
output winding 28 again has two turns for the reasons mentioned.
Also threading the core are drive windings including an advance
winding 30 which is made to link the major aperture of the left
hand portion of the core by several turns and an advance winding 31
made to link the major aperture 12 by several turns. The clearing
windings serve to cause an advance of intelligence stored in the
core and are pulsed at separate times in an advance cycle. A
further drive winding 32 is provided to prime the core through one
turn made to link both transmitter apertures 18 and 22 and operable
to prime the material about such apertures prior to transfer
initiated by the advance pulse of the transfer cycle.
In an actual core like 10 the apertures 18 and 22 have diameters
which were approximately 0.030 of an inch. In order to provide
windings it is necessary to insert insulated wires on the order of
a few mills in diameter through these apertures. Where there is
more than a single turn around the legs as in loop 24 it is
necessary to carry the wire back through the apertures again in the
manner indicated in FIG. 1. Aside from the difficulty of inserting
small wires through small apertures, other problems are encountered
including the possibility of scraping insulation off of the wires
by engagement with the hard and abrasive ferrite material employed
for cores. As will be appreciated by those skilled in the art, the
wiring procedure for devices like shown in FIG. 1 is almost
altogether manual and, notwithstanding a considerable skill
developed to do this task, variations in skill and approach from
worker to worker tend to result in undesirable variations in
windings from core to core.
Techniques which might permit an automated manufacture such as
plating of conductive paths or jig mounting of conductors have
proven to be extremely difficult with core structures like that of
10, which is representative of a typical core winding scheme. Those
skilled in the art will appreciate that many applications call for
considerably more turns placed through an aperture than those
shown.
Turning now to FIG. 2 there is shown a core 40 having the same
overall function as the core 10 shown in FIG. 1. The core 40
includes major apertures 42 and 44 and the leg widths of the
various legs of magnetic material are substantially the same or the
equivalent to those in core 10 in FIG. 1. In lieu of simple minor
apertures having multiple apertures at input, output and drive
positions in these legs, the invention contemplates a series of
turn positions placed in a closely spaced pattern to simulate
multiple turns through a single aperture with the material itself
serving to insulate between turns. These positions are labeled A,
B, C and D, for the left half of the core, the right half having a
similar array. The positions A, B, C or D may be defined by either
holes or by conductive material, wires or pins. In accordance with
one embodiment of the invention and contemplated thereby, a core
like 40 may be molded, cast or pressed out of suitably prepared
magnetic material to have the small holes therein in the pattern
shown. The holes are made just large enough to accommodate a
conductive pin or wire which is placed therein with the core then
being fired with the wires in place. If this procedure is followed
the wire utilized is, of course, uninsulated and must be of a
material to withstand the considerable firing temperatures
employed. With ferrite material systems having firing temperatures
up to 2,600.degree. F. conductors such as platinum are recommended.
It has been found that molding or casting is preferable when the
holes are as small as is contemplated by the embodiments herein
described, although pressing is fully contemplated.
Alternatively, and as another embodiment, the cores may be molded,
cast or pressed in the geometry shown with small holes therein; the
core fired and then, after firing, conductive material placed in
the holes in the form of either precut pieces of uninsulated wire
or plating material deposited therein.
As far as the invention is concerned the choice of one of the above
procedures will depend to an extent upon the particular material
used, the amount of usage contemplated for a given core geometry,
and overall, the extent to which expected production will permit
savings to be made. It is fully contemplated by the invention that
the techniques may also be used to advantage with materials which
do not require firing to the temperatures of the magnesium, copper
or cobalt ferrite systems presently in use.
FIG. 3 shows the core of FIG. 2 with conductive wire or pin members
P located at the input and output positions in the core. FIG. 4
shows the core of FIG. 3 in section with certain of the members P
shown therein. In FIG. 5 a corner of the core 40 is shown enlarged
with A, B and C, as positioned in a leg of the core. As a basic
aspect of the invention A, B and C are positioned relative to each
other with a certain spacing relative to the amount of material
which will be linked when the conductive members P are joined to
windings. Consider first the prime winding shown in FIG. 1 as lead
32 linking aperture 18 to prime flux set in the inner leg around
into the outer leg of material surrounding 18. Referring to FIG. 6,
a portion of the core is shown with the position A emphasized and
the positions B and C, for the moment, de-emphasized and with flux
set in the core as it would be when the left hand of the core
contains a binary 1 or is in a set state. If a current is applied
to P in the polarity shown in FIG. 7 an MMF will result which will
switch the flux in the material about the pin, not under the
coupling loop turns, into an orientation as indicated in FIG. 7.
This is known as priming and the core half is driven into a primed
set state preparatory to a transfer of the state stored in the
core. As can be appreciated from FIG. 5, the amount of flux which
can be transferred via the coupling loop is dependent upon the
amount of flux set into the outer leg when the core is primed. The
placement of position A with respect to the cross-section through
the core material determines this amount of flux and, with the
invention, the amount of flux which can be switched can be easily
controlled.
In FIG. 5 there is shown a third cross-sectional area AWIII between
A and a tangent touching both B and C. Generally, this area should
be made as small as possible. For best efficiency on transfer of a
binary 1 the areas should be made so that AWI is equal to or
greater than AWII + AWIII. For minimum binary 0 output the areas
should be made so that AWI + AWII - AWIII is equal to or less than
the area represented by W.
FIG. 8 shows a portion of the corner of the core with conductive
member P placed through the positions B and C and with leads
attached thereto for the purposes of illustration to form a
coupling loop linking the outer leg of core material by two turns
equivalent to the windings shown in FIG. 1 or loop 24. The loop
load is as represented. Current cause to flow in a coupling loop is
dependent upon the voltage induced in these turns by flux switched
thereunder. This flux is controlled by the amount of material in
the cross-sectional areas BW or CW, shown in FIG. 5; the lesser
area controlling if the areas are different. The total current
caused to flow in the coupling loop is then the net current
resulting from voltage induced in the windings responsive to flux
switched through cross-sectional areas in BW and CW. It may be
desirable to place points B and C relative to the core geometry to
define a net cross-sectional area of material in which the flux
switched is approximately equal to that switched in AWI so that the
amount of flux switched during transfer under clear drive is
substantially the same as the amount of flux primed under the
coupling loops by the priming MMF applied to the conductor through
position A. Again, the invention technique permits a variation in
the amount of flux switched under the coupling loops by varying the
positions B and C relative to the position A.
As can be appreciated, and as an important aspect of the invention,
the winding difficulties which accompany the prior art approach, as
indicated in FIG. 1, are reduced. Even in applications wherein it
is desirable to place fixed pins through small apertures it has
been found to be easier relative to the prior art to place fixed
length, fixed size pins through fixed size apertures and then to
connect such pins through printed circuits, soldering tabs or the
like; easier from both a production control standpoint and labor
involved. More importantly, the devices which result from the
invention technique have a more consistent performance and,
therefore, the overall reliability of a system is improved.
FIGS. 9, 10 and 11 relate to another embodiment of the invention,
including a larger two bit position core structure having windings
plated thereon to form a circuit like that of FIG. 1. The core
shown as 50 includes four major apertures 52, 54, 56 and 58,
defining four major paths of flux closure labeled O.sub.1, E.sub.1,
O.sub.2, E.sub.2 to represent odd and even bit positions. At the
four outside corners are positions A, B, C for prime and coupling
loop turns. The position D is for an input to the core and,
particularly, to the bit position O.sub.1. A further position E is
provided for a coupling loop input from a bit position such as
O.sub.1 to a bit position such as E.sub.1. The center aperture 59
is provided to eliminate nonsaturable material.
In accordance with the invention, the core 50 is molded with small
holes at A, B, C, D and E. The core is then fired, cooled and the
entire core is plated with plating material being deposited through
the holes at A, B, C, D and E. Next, through standard photo-etch
procedures, the windings shown in FIG. 7 are formed on the core
structure. These windings include a prime winding 60 which extends
through each position A to prime each bit position. The polarity
shown indicates the desired circuit for serial transfer from
O.sub.1 to E.sub.1, E.sub.1 to O.sub.2, O.sub.2 to E.sub.2 and out
of the core. The coupling loops are formed as at 62, linking
O.sub.1 to E.sub.1 ; at 64, linking E.sub.1 to O.sub.2 ; and at 66,
linking O.sub.2 to E.sub.2.
The linking conductive paths forming these windings are positioned
so as not to contact each other, but to join with the positions A,
B, C and D to complete the circuit.
Next, the entire assembly is insulated by a standard coating
process and a second winding pattern forming the advance turns is
deposited as shown in FIG. 10. FIG. 11 shows the insulation as 80.
Winding 70 represents advance O drive and 72 represents the advance
E drive. With suitable input and output connection made to the
positions for advance and prime drive and for intelligence input
and output, the structure may then be used as a two bit shift
register.
It is contemplated that a variety of circuit devices having any of
the additional standard functions such as logic or nondestructive
readout may be made utilizing the invention technique.
In a core like 50 for shift register use the dimension in inches
were as follows:
W = 0.063
awi = 0.044
awii = 0.028
awiii = 0.012
having now disclosed and described the invention in terms intended
to enable its practice in a preferred mode, we define it through
the appended claims.
* * * * *