Hi Steve,

The Humiseal manual suggests "1B73 can be removed by most organic
solvents including alchols, common terpines, conformal coatings thinners
and semiqueous cleaning solutions"

The actual Humiseal thinner for 1B73 is Humiseal thinner 521.

I know that's not specifically what you asked, but it may help.  I
beleive you'll need to strip the board and recoat after repair
regards

Greg Major

> -----Original Message-----
> From: Stephen R. Gregory [SMTP:[log in to unmask]]
> Sent: Tuesday, May 18, 1999 9:55 AM
> To:   [log in to unmask]
> Subject:      [TN] Rework of Acrylic Conformal Coated Boards
>
> Hi ya'll!
>
> We just got a rework job in from a customer where we're gonna change a
> PLCC28
> out for them, remove it and replace it with another. The board has
> been
> conformal coated with an Acrylic conformal coating (Humiseal type 1B73
> I
> believe...).
>
> I know reworking can be done just by burning through the coating, and
> then
> cleaning up the pads real good before putting the new part back down.
> We're
> water soluble, so we're gonna have to run the boards through the
> cleaner to
> clean the flux residues...and I know that we'll damage the coating
> when
> putting it through the cleaner. On the boards that I've looked at, the
> coating has been compromised anyway on spots here and there just from
> the
> handling...acrylic is not too tough.
>
> I told our customer that the coating was gonna be pretty raggy looking
> when
> he got the boards back from us, and we're not in the conformal coating
> business. But what's bothering me, is that I think they've got some
> spray
> cans and they're gonna try and touch-up things themselves...against my
> strong
> recommendations. I think the boards should be stripped of the coating
> that's
> on there now, baked, and then re-coated.
>
> But like I said, we're not in the conformal coating business, and I've
> not
> worked much with the stuff anyway. I'm just thinking logically about
> it...am
> I sweating things too much?
>
> Thanks!
>
> -Steve Gregory-
>
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