What PCB Cleaner to use ?

[Albert101]

Hello,

I need to do a repair to a PCB for my dishwasher and the side that is soldered seems to be covered by some sort of varnish or painted translucent plastic.

What is this coating and how do I remove it in order to desolder a relay that needs to be changed ?

Thank you for your help.

[ddavidebor]

You should only take off a few millimeters with a screwdriver so you can make contact with the tip.

[Psi]

It's most likely conformal coating to protect the circuit from the corrosive effects of the steam which contains dissolved washing powder.

[Albert101]

And I should reapply some conformal coating after my repair is done correct ?

Thanks so much for the info.

[moemoe]

Yes, you probably should, the manufacturer didn't apply it without a reason.

I myself use "Urethan 71" from Kontakt Chemie, I coated some pcbs built into my motorcycle with it (everywhere but the contact terminals), and it works pretty well: http://www.crcind.com/csp/web/ProdDisp.csp?lng=3&idx=2827553&country=GE&product=URETHAN%2071&business=ELECTRONIC&CSPCHD=00000001000034uziMS6DB0000I5uvOzre8o9Mub7hDdgS1w--


Just found this funny video when looking for an english page of the manufacturer:

[ConKbot]

Depending on how thick/heavy the material was, I'd go for using a soldering iron tip that wasnt my favorite, and doing it in a well ventilated place, and forget about even removing the coating.  once you desolder it, you can scrape off the crispy bits, clean up your joint, replace the relay.  Seal it back up something when youre done.  Silicone would keep water off, but is still permeable to water vapor.  Something like marine goop would be commonly available, and keep water vapor out, but it certainly wouldnt be the prettiest repair.