Hi, Lakshmi,
Several diverse reasons:
1. to carry out major mods, ensure the boards are properly clean and leave
the board looking aesthetically clean again afterwards.
2. to carry out ICT (In-Circuit Testing) on the board. When you have 2000
test points on a board, you can't mask them against coating and if you need
to test the board again after coating (field failure, mod programme, etc)
you have to remove the coating to allow the test jigs to make proper
contact. It's more straight-forward than trying to locally clean all those
test points.
3. after a number of local mods or repairs, the coating looks pretty rough
and there's a good chance that it's no longer as effective as it should be,
so for aesthetic reasons again, but mainly to ensure adequate coating
performance and the minimum of entrapped residues, we strip and re-coat
boards.
Our product is class 3, Avionics, so has to be always as good as we can get
it.
Peter
Lakshmi Dwivedula <[log in to unmask]> 15/04/2003 07:36 PM
Sent by: TechNet <[log in to unmask]>
Please respond to "TechNet E-Mail Forum."; Please respond to Lakshmi
Dwivedula
To: [log in to unmask]
cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
Subject: Re: [TN] Con Coat Stripper masking materials
One of the reasons that Acrylic based Humiseal IB31 became popular (against
its polyurethane material) is because of its ability to allow rework
without stripping. Why do you need to strip the coat? You can perform the
modifications, (clean the soldering iron tip) and spot recoat with a brush
under a UV Light.
Regards,
Lakshmi Dwivedula
(978) 256 6214
Mail to: [log in to unmask]
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