Hija Steve and all,
Kapton is really a great insulator, which is why it has been used so
extensively in transformers, including high voltage transformers. Someone
said it is bad news to use Kapton when you have corona --- no, the real
problem there is the corona, not the Kapton. I have not found anything that
works when you have corona --- corona will cause failures, it may take some
time, but it will happen.
The one weakness I found in Kapton was that it is very susceptible to
puncturing. So if you use it as an insulator between two flat surfaces that
are presed together, you have to make sure that those surfaces are free of
burrs.
I suppose that is why cables with polyimid insulation have a hard time
handling abbrasion on or over "sharp" corners, and maybe that is one reason
why UL does not allow cables to run across sharp corners. So make sure you
are flying in a "UL approved" airliner :).
Enjoy,
Ahne Oosterhof.
A-Laser, Inc
(503)641-9428
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Stephen R. Gregory
Sent: Monday, November 01, 1999 20:22 PM
To: [log in to unmask]
Subject: [TN] Kapton (Tm) materials...
Hi ya'll,
Not to start another thread about something that will upset people, but
lately in the media there has been some talk about Kapton (tm) materials
being somewhat unstable at elevated temperatures...there's stories about
this
with the recent crash of Egypt Air flight 990...
I, as undoubley as possibly many of you, have always understood that Kapton
(tm) tapes are what you should use when high temperatures are encountered.
I've used it on numerous assemblies to in the past to prevent such things as
a metal connector body connecting to a via that was mistakenly laid-out
without mask beneath the footprint. As a big as a pain in the butt as it
was,
we would cut a teeny piece of kapton (tm) tape to cover a via so that there
was no chance of a via to short to the connector. This is just one
example...there have been many other instances in the past (crystals,
oscillators, etc..) or with other components where I've used Kapton (tm)
tape
to do similar things...the tape needed to stay with the assembly as a
finshed
product.
Should I, or designers who specify the use of Kapton (tm) in this manner be
concerned about this? Or is this just media hysteria?
-Steve Gregory-
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