Can we talk about the temp rise? You say a 45 deg C rise may be to
extreme...if i'm using an all Polimide material, dosen't this material have a
high glass transition range (TG), so I could go on past 45 deg?
I do split traces, but would rather use 3 oz. copper in this application. My
flex needs to bend one time, it could even stay bent. All i'm doing is
replacing a wire harness. Is there something out ther like a wire bonded
on a flex?
=======================================================
 A 45 deg delta may be to extreme even if the laminate is able to
withstand it.
What we have done is split the trace.  This is part of what note 5 in the
IPC-D-275 hints at.  Ten 10 mil traces are as good as one 100 mil trace.
Also be careful of the copper weight.  An easy way to carry more
current is to use a heavier copper but in a flex circuit the key word is
"flex".  It's hard to bend a bus bar.  We try not to use anything greater
than 2 oz.

Good Luck


Michael L Vaughan
Lockheed Martin Astronautics Denver Colorado
(303) 977-7959  [log in to unmask]


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