EoW January 2012

87 / 132

EuroWire – January 2012 85
Technical article
Stephen Pearson
Tyco Electronics
Greensboro
North Carolina
USA
Email:
Website:
Kenneth E Cornelison
Beta LaserMike
Dayton
Ohio
USA
Email:
Website:
▲ ▲ Figure 11: Spike at 80 MHz in one trial
▲
▲ Figure 12: Spike missing at 80 MHz after pretwist changes
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▲ Figure 13: Spike reduced at 125 MHz after pretwist changes
Mainly, lay variation signatures are found
at the fundamental pair lay length, the
twinner bow speed and the pretwist
speed.
The nominal lay length values are
affected by changes in process set
points, specifically pretwist ratio and its
interaction with bow speed.
Quantitatively, these changes are
relatively small. But there appears to be
a relationship between the inputs and
the lay lengths that would require further
validation for statistical significance.
An additional and potentially larger
impact to the nominal lay length can be
seen between machine types.
Subsequent processes can add to or have
an impact on the variation signatures.
This was evident in the measurement of
pairs at cabling.
Additional signatures for cabler bow speed
and take up spool diameter were seen.
Finally, and most importantly, crosstalk
performance is significantly affected by
the process changes in these experiments.
Investigation into the changes in lay
length values as well as changes in the
variation signatures are needed to verify
the contribution from each factor.
It is reasonable to assume that there are
other process inputs that could have an
impact to the lay variation as there are
other unexplained signatures seen at
both twinning and cabling. Their impact
to crosstalk performance would require
further investigation. n