Metallic magnetic alloy foil preparation for development of non-destructive readout buffer memory planes using laminated layer techniqu

Janus, T. P.

Kenny, N.

English

NASA Technical Reports Server

c 
FABRICATION AND DELIVERY OF NON-DESTRUCTIVE READ OUT 
MEMORY BUFFERS USING LAMINATED LAYER TECHNIQUE 
First Quarterly Progress Report 
Contract N o .  N A S 8 - 1 1 9 8 6  
Submitted by : 
MATERIALS RESEARCH CORPORATION 
Orangeburg, New York 
September 13, 1965 
MRC Number 520 
https://ntrs.nasa.gov/search.jsp?R=19660008871 2020-03-16T23:31:13+00:00Z
TABLE OF CONTENTS 
Sect ion Page 
I. INTRODUCTION... ........................... 1 
11. MATERIALS AND PROCESSING.................. 2 
A. Composition o f  Alloys ................. 
B. Melting P r o c e d u r e . . , - - . . , . - . - . - - - - - - - -  
C. Rol l ing  and S l i t t i n g  Schedule.. ....... 
E. L ~ n a t i n g . . . . . .  ..................... 
F. Photo Etching. ........................ 
D. ~nesling. ............................ 
2 
2 
3 
4 
5 
6 
I11 . TEST APPARATUS.... ........................ 7 
IV. PLANS FOR NEXT QUARTER... ................. 8 
LIST OF FIGURES 
Figure 1 - Zone Refining Apparatus 
I' 2 - Rolling Equipment 
I' 3 - Prepared F o i l s  
It 4 - Annealing Furnace 
" 5 - Laminating Press 
" 6 - Photo Resist Spinner 
7 - Photo Etching Artwork 
8 - Magnetic Tes t  Specimen 
9 - Hysteres is  Loop Apparatus 
'* 10 - Hysteresis Loop 
" 11 - Switching Speed Apparatus 
" 12 - Electronics  Modules 
1 
I 
I 
I 
I 
1 
I 
I 
I 
8 
8 
I 
m 
I. INTRODUCTION 
The genera l  ob jec t ive  of Phase I of this program i s  t o  
explore  materials and processing techniques u s e f u l  i n  the 
G G V G ~ U ~ G I J ~  u? l u w  GUS& ? u u n - d e s i r u c i i v e  readout buzter 
memory p lanes ,  which are suscep t ib l e  t o  ba t ch  o r  con- 
t inuous  processing techniques.  
the u s e  of m e t a l l i c  magnetic a l l o y s  that  are r o l l e d  i n t o  
f o i l  sheets approximately six t o  t e n  microns th ick .  T h i s  
f o i l  approach is a non-vacuum technology, except  fo r  the 
prepara t ion  of the s t a r t i n g  r a w  materials. 
f irst  q u a r t e r  of this program, w e  have prepared f o i l s  
w i t h  f i v e  d i f f e r e n t  compositions, assembled magnetic 
anneal equipment ? es t ab l i shed  photo-etching and laminat ing 
f a c i l i t i e s ,  and constructed magnetic parameter measuring 
equipment, T h i s  r epor t  descr ibes  and i l lus t ra tes  this 
progress .  The reader w i l l  be a ided  by v i s u a l i z i n g  a 
minia ture  processing l i n e  that begins w i t h  r a w  m a t e r i a l s  
prepara t ion  and ends w i t h  magnetic tests.  One ob jec t ive  
of  this processing l i n e ,  of course,  i s  t o  e s t a b l i s h  
c o r r e l a t i o n  among materials composition, processing 
v a r i a b l e s ?  c rys t a l log raph ic  s t r u c t u r e ,  and magnetic 
parameters, This information then w i l l  be used i n  Phase 
I1 i n  memory c e l l  device design. 
Our approach i s  t o  explore 
During the 
-1- 
11, MATERIALS AND PROCESSING 
A, Composition of Alloys - 
Three a l l o y s  were chosen f o r  i n i t i a l  i n v e s t i g a t i o n :  
UL.>~ ~ 1 ,  i6.5$ Fe, n, c r ~  --. Aiiuy #i 
Alloy #2 
Alloy #3 
Mo, 79% Ni, 17% Fe. 
3% Co, 80% Ni, 17% Fe. 
These a l l o y s  a r e  commonly used i n  small s i g n a l  
magnetic app l i ca t ions  and were s e l e c t e d  t o  determine if 
more careful c o n t r o l  of composition and f a b r i c a t i o n  pro- 
cedures would r e s u l t  i n  magnetic p r o p e r t i e s  that are s ig -  
n i f i c a n t l y  more uniform than t h e  p r o p e r t i e s  of commercially 
prepared mater ia l .  
Zn add i t ion  t o  the above a l l o y s ,  f o i l s  of pure i r o n  
and pure n i c k e l  were a l s o  prepared f o r  comparison purposes. 
F ina l  analysis f o r  t r a c e  impur i t i e s  w i l l  be performed 
after hea t  t reatment  t o  e l imina te  undetected contamination. 
B. Melting Procedure - 
The s t a r t i n g  metals  used i n  the above a l l o y s  were 
rods of high p u r i t y  i r o n ,  n i c k e l ,  molybdenum and coba l t ,  
a l l  of  which had been t r i p l e  pass  zone re f ined .  
gram charges of the a l l o y s  were weighed on an a n a l y t i c a l  
balance and then ar'c melted i n  an argon atmosphere t o  
consol ida te  and homogenize the a l loy .  
Eighty 
-2- 
The a l l o y s  were i n  the form of rods after a r c  mel t ing,  
were then placed i n  a zone r e f i n i n g  apparatus  ( s e e  Fig.  1) 
and then double pass zone  l e v e l e d  and vacuum degassed. 
A f t e r  zone l e v e l i n g ,  the rods were i n  the form of rods 
approximately one-half inch  in diameter by six inches long. 
C. Rol l ing  and S l i t t i n g  Schedule - 
The a l l o y  rods were co ld  r o l l e d  on a two-high 
S tana t  r o l l i n g  m i l l  (see Fig. 2)  t o  tape  0.008 in .  t h i c k ,  
s l i t  t o  the desired w i d t h  ( l / l+ - l /Z  i n c h )  and r e - r o l l e d  on 
a four-high Stana t  m i l l  t o  a th ickness  of  0.002 inch. The 
t a p e  w a s  taken t o  a Sendzimer m i l l  and further r o l l e d  t o  
0,0005 in. th ick .  Samples o f  t he  tape were taken a t  var ious 
th icknesses  f o r  magnetic and m e t a l l u r g i c a l  tests. 
During the r o l l i n g  sequence, the tape d id  n o t  r ece ive  
any in te rmedia te  stress r e l i e f  anneal which might have 
caused contaminants t o  diffuse i n t o  the a l l o y .  
During r o l l i n g  the tape experienced a 99 percent  re- 
duct ion in area which i s  a r e l a t i v e  measure  of the deformation 
energy contained i n  the sample. The deformation energy i n  
tu rn  in f luences  t h e  annealing k i n e t i c s  o f  the foil. 
Fig. 3 i s  a photograph of f o i l s  of va r ious  th ickness  
and w i d t h ;  t h e  wide foil on the r i g h t  i s  0.0005 i n .  t h i c k  
and 4 inches w i d e .  
-3 - 
I 
II 
1 
1 
I 
I 
I 
1 
I 
D. Annealing - 
The main reason f o r  anneal ing the  f o i l  i s  t o  
e l imina te  the s t r a i n  energy of  deformation , and thereby 
reduce the coercive force  and inc rease  the switching speed 
of the f o i l .  
I n  some app l i ca t ions  i t  i s  desirable t o  induce 8 
magnetic u n i a x i a l  anisotropy i n  the f o i l .  This can a l s o  
be accomplished in t he  three alloys under i n v e s t i g a t i o n  
by cool ing the f o i l  from the anneal ing temperature through 
the Curie temperature,  i n  t h e  presence of an o r i e n t i n g  
magnetic f i e l d .  
The furnace i n  which t h e  anneal ing i s  performed i s  
shown i n  Fig. 4. It is capable of reaching 12OO0C, al- 
though best  results f r o m  annealing permalloy have so f a r  
been achieved by holding 1 hour a t  10sO°C. An Inconel 
r e t o r t  i s  shown i n  t h e  furnace in Fig. 4. which permits  
anneals  t o  be c a r r i e d  o u t  i n  i n e r t ,  ox id iz ing  o r  reducing 
atmospheres. 
The o r i e n t i n g  magnetic f i e l d  i s  suppl ied  by an aux- 
i l i a r y  winding wrapped on the rec t angu la r  m u f f l e  shown 
in the furnace.  It i s  capable of producing a 15 o e r s t e d  
D.C. magnetic f i e l d  w i t h i n  the furnace.  
Experiments are s t i l l  under way t o  determine the b e s t  
combinations of anneal ing t i m e s  and temperatures (and magni- 
t u d e  of o r i e n t i n g  f i e l d  when an easy axis i s  desired).  
-4- 
E. Laminating - 
One of the advantages of f a b r i c a t i n g  memories from 
mounted p l ana r  f o i l s  of permalloy i s  that i t  i s  poss ib l e  t o  
change the geometry of the f i n a l  memory b i t  without changing 
the technology of mounting the permalloy f o i l s .  
the two memory designs s u b m i t t e d  i n  the proposal f o r  this 
c o n t r a c t  can be constructed by s tacking  l a y e r s  of a copper- 
clad d i e l e c t r i c ,  a d i e l e c t r i c  c l a d  w i t h  permalloy on both  
sides, and another  copper-clad d i e l e c t r i c .  The only d i f -  
f e rence  i n  f a b r i c a t i n g  the t w o  designs i s  i n  the photo 
resist artwork. In f a c t ,  i t  i s  poss ib l e  t o  th ink  of o t h e r  
des igns  which can a l s o  be made from t h e  same combinations. 
For  example, 
W e  are s tudying the lamination of permalloy and copper 
sheets on var ious  d i e l e c t r i c s .  
a r e  us ing  i s  shown i n  Fig. 5. 
pres s  capable of b o t h  hea t ing  and cool ing cyc les .  
The l abora to ry  p r e s s  w e  
It i s  a s tandard  laminat ing 
There are two general  approaches t o  the lamina t ing  
procedure : 
1. Laminate the f o i l  i n  the a s - r o l l e d  condi t ion and 
then anneal the mounted f o i l .  
nique i s  that the f o i l  can be easily handled a f t e r  anneal ing 
without  s t r a i n i n g  i t .  The disadvantage,  of course,  i s  that 
b o t h  the d i e l e c t r i c  substrate and the adhesive m u s t  be 
capable of withstanding the anneal ing temperature of 1,OOOOC. 
The advantage of this tech- 
-5- 
2. Anneal the f o i l  and then laminate t o  a s u b s t r a t e .  
The advantage of this technique i s  that one has a wider 
range of adhesives and d i e l e c t r i c s  from which t o  choose. 
The disadvantage i s  that one m u s t  be c a r e f u l  t o  minimize 
s t r a i n i n g  the f o i l  during lamination as one m u s t  be care- 
f u l  t o  ensure that if s t r a i n  does occur, i t  i s  uniform 
over  the plane of  the f o i l .  
F. Photo Etching - 
Samples f o r  magnetic t e s t i n g  are prepared by 
photo e tch ing  techniques common t o  the s o l i d - s t a t e  e lec-  
t r i c a l  f i e l d .  A photo res i s t  Coated laminated f o i l  under- 
goes u l t r a - v i o l e t  exposure through a mask. 
t h e  photo resist, the opera tor  immerses the laminated f o i l  
i n t o  an e t ch ing  bath where chemical m i l l i n g  takes  place.  
Af t e r  developing 
Uniform coa t s  of  photo r e s i s t  are spread over t h e  
laminated f o i l  by c e n t r i f u g a l  f o r c e  spinning ( s e e  Spinner 
i n  F i g .  6 ) .  The artwork used t o  prepare u l t r a - v i o l e t  ex- 
posure masks i s  shown in Fig .  7, and an etched c i r c u l a r  
specimen in Fig. 8. 
- 6- 
1 ' 
111. TEST APPARATUS 
Two bas i c  p i eces  of magnetic t e s t  apparatus  are 
a v a i l a b l e  f o r  cha rac t e r i z ing  the h y s t e r e s i s  loop and 
=zZtc?Azg z:pzsZ ~f tliz yroceuseci Zoii..  m e  magnetic 
h y s t e r e s i s  loop t r a c e r  i s  shown i n  Fig. 9,  and a t y p i c a l  
h y s t e r e s i s  loop obtained w i t h  th is  apparatus  i n  Fig.  10. 
The switching speed apparatus  i s  shown i n  Fig. 11. 
These p ieces  of equipment are s i m i l a r  t o  equiprnents a t  
Georgia Tech and NASA Huntsv i l le ,  and w i l l  g r e a t l y  a i d  
the interchange of  information among the s e v e r a l  groups 
of workers. 
__  
Elec t ron ic s  modules that w i l l  d r i v e  and sense the 
f i n a l  prototype memory plane are shown i n  Fig. 12. 
-7- 
IV PLANS FOR THE NEXT QUARTER 
During the next  q u a r t e r ,  w e  w i l l  emphasize magnetic 
parameter t e s t i n g  of the f o i l  materials. Coercive fo rce ,  
squareness ra t io;  9 ~ 5 t c k i ~ g  s i 2  ~ i i t s ~ t  a i g r i a i  ciata 
w i l l  be c o r r e l a t e d  w i t h  the materials and processing 
v a r i a b l e s  . These measurements will y i e l d  information 
use fu l  i n  s e l e c t i n g  the process v a r i a b l e s  most u s e f u l  
i n  the design and f ab r i ca t ion  of t he  prototype memory 
ce l l s  . 
Laminating techniques a l s o  w i l l  undergo fur ther  
s tudy,  I n s u l a t i n g  backing m a t e r i a l s ,  adhes ives ,  and 
heat t reatment  m u s t  be combined i n t o  a process  that 
yields minimum strain induced non-uniformity i n  the 
memory c e l l s .  
In add i t ion  t o  t he  magnetic measurements and Lamin- 
a t i n g  procedures, memory c e l l  design and f a b r i c a t i o n  w i l l  
commence i n  the next  qua r t e r ,  The knowledge of anisotropy 
f i e l d ,  d i spe r s ion ,  and coercive f o r c e  obta ined  from meas- 
urements on the prepared foil w i l l  be u s e d  i n  the  design 
work. 
Two designs a r e  ava i l ab le  f o r  the non-destruct ive 
readout mode. T h e  f i r s t  design r equ i r e s  that the magnetic 
f o i l  have very s m a l l  d i spers ion  and that t h e  anisotropy 
f i e l d  be uniform f o r  a l l  elements. W i t h  the  f o i l  s p o t s  
-0- 
I 
I 
magnetized along their  easy axes,  a r e v e r s i b l e  p a r t i a l  
r o t a t i o n  of the magnetization vec to r  w i l l  r e su l t  when 
the word l i n e  i s  energized i n  the d i f f i c u l t  d i r e c t i o n .  
The second design uses a double element, w i t h  the aniso- 
t ropy  i n  one of the f o i l  spo t s  being about t e n  t i m e s  
l a r g e r  than i n  i t s  superposed neighbor. I n  e f f e c t ,  the 
h i g h  an iso t ropy  spo t  serves  as a permanent magnet, w h i l e  
t h e  low anisotropy spot  se rves  as a read-out .and as a 
keeper t o  provide a re turn  f l u x  path. 
given memory c e l l  geometry depends upon, among o t h e r  
f a c t o r s ,  the uniformity of magnetic p r o p e r t i e s  i n  the 
s t a r t i n g  f o i l  material. 
The choice of any 
.I 
M 
1 
I 
-9- 

- 
I 



i 
cd 
ct 
o r  
k 
f ill 
i 
f 
ci- 
0 


I 
i 
I 
I 
I 
Figure 10 
Hysteresis Loop 
I 
1 
I 
1 
1 
I 
I 
I 
I 




Fabrication and delivery of non-destructive read out memory buffers using laminated layer technique First quarterly progress report

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server