Coil etched from conductive film has better field uniformity than wire-wound coils and less coil loss at high-frequency operation

Chen, T. T.

Ypma, J. E.

English

NASA Technical Reports Server

September 1975	 B75-10195 
NASA TECH BRIEF 
Langley Research Center 
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. 
Stripe-Line Coil for Magnetic-Field Generation 
in Bubble Memory Devices 
An improved coil for magnetic bubble memory 
devices consists of a stripe-line coil pattern with 
varying widths of conductor etched from a conductive 
film supported on a polyamide film. The multiple-
layer stripe-line coil has conductors in series along the 
layer direction, rather than in the axial direction, 
which minimizes potential differences. The stripe-line 
layer is wrapped around a fixed coil form, and the 
outer ends of the conductors are electrically connected 
as a single loop to form a field coil (see illustration). 
Conductor length, width, and spacing are controlled 
by the etched pattern, resulting in coil parameters, 
such as size, shape, and the like, with less variation 
from run to run than in wire-wound coils. The
stripe-line coil arrangement is also simpler, easier to 
wind, and has better field uniformity inside the coil 
and less coil loss at high-frequency operation. 
The printed-circuit magnetic-field coil is produced 
on a flexible conductor substrate by etching the 
desired stripe-line pattern on a conductor foil 
supported on an insulating film. Preferably, this 
consists of cold-rolled copper on a polyamide film. 
Photolithographic techniques provide one method of 
forming the stripe-line pattern of the conductor layer. 
The copper surface is coated with a thin layer of 
light-sensitive photoresist, and the coated surface is 
exposed to light through a photomaster with the 
desired stripe-line design. The conductor material is 
then developed and etched to produce the pattern. 
End of Stripe
Line
Winding 
Starts 
Solder 
Joints 
Winding 
Ends	 Note: 1-2-3-4-5-6 represent the sequence of 
Conductor	 Insulator	 current flow in the conductors. 
Stripe-Line Coil for Magnetic Bubble Memory Devices
(continued overleaf) 
This document was prepared under the sponsorship of the National	 Government assumes any liability resulting from the use of the 
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.
https://ntrs.nasa.gov/search.jsp?R=19750000195 2020-03-19T20:28:05+00:00Z
The multiple-layer stripe-line coil structure sub-
stantially reduces the high-frequency loss in two ways: 
Sufficient spacing between the layers or columns of 
conductors can be provided to reduce the interwire 
coupling, and secondly, with the winding in the coil 
connected in series, the current will flow through 
adjacent vertical arrays or columns of conductors. 
This winding arrangement minimizes the potential 
differences between neighboring turns, thereby 
minimizing high-frequency loss due to interwire 
coupling. The arrangement also helps to minimize the 
unequal current distribution at high frequencies 
which occurs in coils with parallel-wound layers. The 
effective turns in this winding scheme can be 
controlled by varying the conductor width. (By 
increasing the conductor width, the number of 
effective turns in the winding is decreased.)
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Langley Research Center 
Mail Stop 139-A 
Hampton, Virginia 23665 
Reference: B7540195 
Patent status: 
Title to this invention has been waived under the 
provisions of the National Aeronautics and Space Act 
[42 U.S.C. 2457(f)], to the Rockwell International 
Corporation, Anaheim, California 92803. 
Source: Thomas T. Chen and

John E. Ypma of

Rockwell International Corp. 
(LAR-11705) 
Categories: 01 (Electronics - Components 
and Circuitry) 
02 (Electronics Systems) 
B75-10195	 08 (Fabrication Technology)


Stripe-line coil for magnetic-field generation in bubble memory devices

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