Re-lacquering PCB's for outside usage?

[Chris Wilson]

I have some expensive outside radio linked PIR sensors and 2 have suffered water ingress. I eventually found the reason they were intermittently faulty was the coating on the PCB's had become slightly conductive and op-amps were doing "funny things". I soaked and washed the boards after dismantling the devices in isopropyl alcohol and dried them slowly. I have found some coatings go soft and are removed by IPA, and some are unaffected. This stuff came off in minutes. They now work fine but I fear usage in an outdoor environment may cause PCB track degradation. I would like to re-coat them with a water proof varnish of some kind. has anyone any experience as to what to coat them with please? Thanks!

[android]

You could try Electrolube DCA SCC3 Conformal Coating. I bought a 200ml spray can recently, but have to admit to not actually using it yet. You can solder through it later if you need to. Pricey though.

[tautech]

Here's a local one for you:
http://uk.rs-online.com/web/p/electronics-varnishes-lacquers/0569290/

I use similar one all the time in our humid climate, even on new home etched PCB's before soldering.
Good for touch ups after rework too.

[Chris Wilson]

Excellent, RS are convenient as I need some other stuff that I can add on to get free P&P. Thanks for that!

[madires]

CRC's SK10 works fine for me. SK10 is flux and lacquer in one, but it's not a conformal coating. I got old home automation stuff I made over 20 years ago and the PCBs still look like new (some mounted in a moisty environment).

[SeanB]

If you only have a few use some 2 part clear epoxy after cleaning the board to coat the boards on each side. Cover all components and wiring so that moisture does not get to the copper.

[wagon]

If you are really tight for funds you can use a clear 'enamel' paint in a pressure pack can.  Do a couple coats.  Works OK, and is good considering you can buy a can of it for about $5.

[Chris Wilson]

Got the RS branded spray coming as per tautech's link, hopefully it will do the job, with luck they'll last another 14 years then Thanks everyone!