Hi Steve,

We use Uresolve Plus Gel from Dynaloy for spot urethane c/c removal (we use Conap CE-1155).  It's a gel so it doesn't run all over the board and works fairly quickly depending on your coating thickness.   We sometimes set-up an "assembly line" and spot strip many boards at a time:  apply the gel, wait, wipe off, rinse, clean, inspect. 

You have to be careful with microblasting.  The operator can easily blast through the coating and into the PWB butter coat or solder mask if they are not careful.  It can be tedious work if you have a large area to do and lots of assemblies.

I think the soldering iron burn through method is OK for small components and small jobs.  However there's always a concern with thermally overstressing the PWB with burn-though c/c removal of through-hole components.  If you are working with surface mount parts you also need to get all the c/c off the pads so you can solder the new part in place, which can be a challenge. 

We've even evaluated a laser removal method but that was not successful due to the normal variations you see in coating thickness across a board.  The laser wasn't "smart" enough to sense the coating thickness and adjust it's power accordingly. 

-- Gregg

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