10/2/2001
Folks, I am seeking technical help on the
pros/cons of removing Humiseal Type 1A33 conformal coating (MIL Spec Type UR)
using Humiseal 1063 Stripper Solvent, or any other solvent that can remove the
coating by dipping. We are returning boards from the field for a
significant amount of rework where removal of coating by conventional means
such as by soldering iron or spot application of solvents is not
practical. The boards are FR4 base material (0.063 to 0.125 inch
thick) with all parts being plated-thru-hole military specification
parts. There are parts such as connectors and numerous Integrated
Circuit sockets where the stripper material could get into. There are
also a significant number of teflon insulated stranded wire jumpers that are
fastened to the board using RTV covered over with conformal coating. The
OEM plans on dipping the complete board in a pan of Humiseal 1063 liquid and
leaving it sit till the coating is dissolved. Cleaning will then be done
using alcohol with DI water applied manually followed by automatic cleaning
via in-line cleaner using solvent and DI water. Omega Meter type ionic
test will then be done on sample basis to verify the ionic contamination has
been removed (Humiseal 1063 stripper is highly conductive).
Has anyone out there removed conformal coating
using Humiseal 1063 stripper or other solvent dipping process. If so,
please advise if you found the process technically acceptable, and please
provide specific process details, including the post cleaning method
used. I would appreciate an answer as soon as
possible.Thanks.
I can be reached at following
contact:
Les Bogert
Bechtel Plant Machinery Inc.
412-829-8489
FAX
412-825-8997