rejected [why??}, and resending message below

-----Original Message-----
From: Alderete, Michael
Sent: Wednesday, May 19, 1999 11:24 AM
To: 'IPCtechnet'
Subject: Polyimide, temperature for discoloration and /or pyrolosis
[charring]


Help.

Anyone know what temperature polyimide [in PWB]:
a. starts to discolor
b. pyrolizes, or chars?

Had similar problem at the last company- 3 phase power, 115V AC, runs into
rig-flex backplanes on F/A-18 targeting pod. Water [salt water or wash down
fluids] was getting into vented elec boxes, and shorting out the 3 phase
power. Fire and black stuff all over inside of box resulted.

Know very little about current design and circumstances, but our guys think
it's a short induced problem. PI material darkens; don't think they see
charring in this instance.

Thanks in advance

Michael

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