JEC COMPOSITES MAGAZINE - Issue #94 - January/February 2015 - 36

nano

Further reductions in CNT yarn
resistivity will be necessary before
CNT conductors are practical for
high-speed signals in longer lengths
or for power. Prototypes of an
RG-316-equivalent coaxial cable
demonstrate the need for higher
conductivity to make CNT cables
practical for general-purpose applications. Both CNT shield-only and
all-CNT constructions offer insertion losses higher than specified in
MIL-STD-17C.

Real-world practicalities
As progress is made toward enabling
the use of CNT materials in cables,
two other issues deserve mention.
The first is how to terminate CNT
cables. CNT conductors are compatible with existing contacts and can
be terminated with standard crimping techniques, albeit with slightly
modified crimp tool settings. Testing
of the mechanical strength of the
crimps suggests that the CNT yarns
fail before the crimp fails. Shields

can be terminated to backshells with
steel bands and other compression
techniques. Tapes and yarns are also
compatible with soldering, although
they require modification of the
CNT surface.
The second issue is moving from
prototypes to production. CNT
yarns, sheets, and tapes are available
in commercial quantities, but challenges remain in volume production
of long parts needed for cable. The
production capabilities of CNT suppliers are rapidly increasing but the
supply chain today typically has long
lead times. Many applications today
- such as semiconductors or composite enclosures - use CNTs measured
in microns or millimetres. Cables
represent a completely different scale
from those applications, requiring
tens of meters.

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university partners to improve the

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conductivity of macroscopic CNT
arrangements, the company has also
manufactured more than 1600 metres
of CNT cable for testing and evaluation. These prototypes suggest that
CNT can be successfully integrated
for use in cable shielding as well as
conductors in relatively low-speed
data cables, such as Databus and
CANBus.
Building on the knowledge gained
from these initial, weight-sensitive
applications, the industry will learn
how to address cost, high volume
demands, and electrical performance. Handling of CNTs in the
form of yarns and tapes means that
manufacturing processes for building
cables need refinement to optimize
throughput and improve yields. n
More information:
To learn more on carbon nanotube
technology, connect with Stefanie at
www.DesignSmarterFaster.com

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CONTACT
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36 jec composites magazine / No94 January - February 2015
http://www.DesignSmarterFaster.com http://www.jeccomposites.com/content/call-posters
JEC COMPOSITES MAGAZINE - Issue #94 - January/February 2015

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