Cleaning PCB's that have been sitting around?

[skiraly017]

I have some Express PCB boards that don't always get used right away and the pads get tarnished.

1) What's the best way to store them so this doesn't happen? Maybe one of those little silica gel pouches in the storage bags?
2) What's the best method to clean them if they are tarnished?
3) I have a small ultrasonic cleaner, could I use it to clean them like the jeweler does with my wife's jewelery? What liquid solution should I use?

Thanks for any advice.

[SonicVI]

Use this stuff.

[skiraly017]

Thanks but these are already tinned by Express PCB, there's no bare copper.

[tranceracer]

I usually put a light coat of Krylon Crystal Clear on the trace side of the PCB that I etch but don't use right away to keep the Cu from becoming oxidized.  The heat of the solder just melts the clear and the clear kind of acts like a fluxing agent but I also put flux on the terminals before I solder the components.

[head_spaz]

ExpressPCB pcb's should already be tinned and soldermasked. I've never had any problems
storing them.

If they are tinned, then just hit the pads with a soldering iron.

For bare copper boards, I use TARNEX.
You can find it anywhere, it's usually found in the cooking supplies section and it's used for
polishing silver-silverware, and copper pans.
I use it to prepare my boards for artwork too. I just wipe it with TARNEX, then sponge it with
BON-AMI, a rinse in cold water, and then just before I start ironing, I swab it with rubbing alcohol.

For long term storage, I spray my boards with Testors clear laquer. It dries almost instantly,
and melts like it's not even there when soldering.

I also give my assembled boards a shot of clear coat too... keeps the moisture out and gives
it a nice "magazine-photo-like" sheen... without being too obvious looking.

[John Lyons]

There are a couple things you could use.
Try a brown grocery bag wadded up.
Seriously...it will work.

If that's not enough to get the oxidation off
then use a green pot scrubber under and
some water from the sink. Dry well and
knock the board on the counter to dislodge
any water in the holes.

I usually use #0000 steel wool on bare
copper boards but this will dull the solder
mask and silk screening on a pro board.

Anything mildly abrasive will work really.

John

[Paul Marossy]

I have found that using an SOS pad (steel wool product) cleans up PCBs very nicely. Never needed to use anything else.

[StarGeezers]

What about the old salt and vinegar trick ? Sure cleans up a penny quick ...

[SonicVI]

Thanks but these are already tinned by Express PCB, there's no bare copper.

I don't think you need to worry about it if they're already tinned do you?