Concept has several important advantages over close-wound system: memory and coil chips are separate and interchangeable; interconnections in coil level are eliminated by packing memory chip and electronics in single structure; and coil size can be adjusted to optimum value in terms of power dissipation and field uniformity

Chen, T. T.

Ypma, J. E.

English

NASA Technical Reports Server

Bias
Substrates 
Hold 
Garnet 
Devices 
WI'
as 
ture 
October 1975 
•	 NASA TECH BRIEF 
Langley Research Center
B75-10219 
H 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Open Coil Structure for Bubble-Memory-Device Packaging 
The open-coil-structure packaging concept for 
bubble memory devices, shown in the illustration, has 
several important advantages over the close-wound 
coil system: 
a. All memory chips and coil chips are separate and 
interchangeable. Individual small packages for 
each coil are not required.
b. Most of the interconnections in the coil level are 
eliminated by packing the memory chip and asso-
ciated electronics in a single structure. 
c. Coil windings are separated from the device; there-
fore coil size can be independently adjusted to an 
optimum value in terms of power dissipation and 
field uniformity. 
Ferrite
Plates With
X-Fleld
and Y-Fleld
Windings
Garnet	 Id	 Ferrite 
Open-Colt-Structure Packaging Concept for Bubble Memory Devices
(continued overleaf) 
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Aeronautics and Space Administration. Neither the United States	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	
will be free from privately owned rights.
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d. Forced air cooling can be easily implemented, for a 
better thermal equilibrium, as the whole structure 
is open. 
In the open coil approach, coil windings are 
wrapped around a ferromagnetic plate such as ferrite 
plate. Because of the magnetic shielding effect of the 
ferromagnetic plate, the magnetic field in the space 
above or below the coil winding is equivalent to the 
field generated by a single layer of conductors. (When 
two identical magnetic plate coils are placed in 
parallel, the magnetic field between the plates is 
identical to that generated inside a close-wound coil.) 
A rotating field network is achieved by winding two 
orthogonal windings around the magnetic chips and 
stacking a number of these chip coils in a bias 
structure. The bubble devices are inserted between 
these coils as illustrated. 
This approach can be extended to bubble-memory-
module packaging where a large number of chips have 
to be driven in several independent rotating fields. All 
memory devices and their associated electronics can 
be mounted in planes, called device planes, and all 
magnetic chip coils and their driver electronics can be 
mounted in separate field planes. The device planes 
are then inserted in between coil planes and are 
placed in the bias structure. All memory chips under 
the same coil windings can be operated as an 
independent unit.
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Langley Research Center 
Mail Stop 139-A 
Hampton, Virginia 23665 
Reference: B75-10219 
Patent status: 
Title to this invention has been waived under the 
provisions of the National Aeronautics and Space Act 
[42 U.S.C. 2457ffl], to the Rockwell International 
Corporation, 3370 Miraloma Avenue, Anaheim, 
California 92803. 
Source: Thomas T. Chen and John E. Ypma of

Rockwell International Corp.

(LAR-1 1704) 
Categories: 01 (Electronics - Components 
and Circuitry) 
B75-10219	 03 (Physical Sciences)


Open coil structure for bubble-memory-device packaging

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