How do you clean old capacitor residue off solder pads? - Answered, thanks

[Platinumfungi]

So I'm just finishing up with a total overhaul on a PC Engine Duo. Everything seems to be working properly, but many of the old surface mount caps left a greenish brownish residue on the solder pads after removal. I tried some Isopropyl alcohol and got the basic filth off but they still look like crap to me.  They work, but I feel a little uneasy about it.  Does anyone know any good way to clean the pads that the caps mount to?

Thanks for any info. I can supply a pic if this doesn't make sense.

[Michael Helgeson]

If you really want to go the limit wash the main board in the dish washer,then let it dry under a fan for 2 days. Other methods are using goo gone,then cleaning the after garbage and oil of the goo gone with alcohol. Or you could just let it be,close it back up and let it stay closed forever.

[nat]

I can second the dishwasher method. IT sounds crazy, but I've used it computer boards before too. It works magic.

The key is allowing sufficient air drying time (at least 2 days). Whatever you do, don't use the oven or other heat-dry methods. Excessive heat can damage PCBs and their components.

[Michael Helgeson]

Yea if you use the dishwasher make sure to remove the pcb before the drying cycle begins.

[Platinumfungi]

Dishwasher eh?  Do you have to remove components from the pcb first? Obviously I'd think the laser assembly would not like soap and water, but then again I'd think everything but the board itself wouldn't...  I've heard of cleaning keyboards that way too though. 

Does the residue have the potential to cause problems that you guys know of?  It seems to work just fine, but I'd like to be sure that it's ok to close up and move on.

Thanks for the input.

[Michael Helgeson]

Well,I'm not sure what type the residue is that your speaking of,is it the flux your talking about? That will be fine,just messy looking. If you wash the pcb to remove it or anything else gunk or mess wise,the chips and caps,ect. stay on the pcb.The cd-drive and wires do not.

Chips and pcbs typically get washed in process via certain methods in some facilities anyway to make sure they are clean before assembly. Water wont hurt the caps,they are plugged to prevent leaking,the same applies during washing,the caps wont allow water in if they are reliable caps. Washing pcbs is  a method as old as time used in electronics repair shops that do their job well. It helps locate broken traces on dusty or dirty pcbs or helps find cold joints or corrosion from acid,ect....

[Platinumfungi]

Good information to know. Thanks again.

[SignOfZeta]

I'm not sure what residue you are talking about. If its flux, just leave it. Likewise if its the oil that sometimes leaks from capacitors, just ignore that too.

If it works, its better to just not f*ck with stuff since if the unit functions, the only two possible fruits of your labors are a) it continues to function, and b) you break something that previously was functional.

[Platinumfungi]

The residue was just gunk from the old caps themselves.  It looks just like the corrosion that batteries sometime leave on the metal contact points of anything that had batteries sit ideal in them for years. Greenish dried up battery acid is the best way I can describe it. 

[Michael Helgeson]

You can try a toothbrush and alcohol too.

[SignOfZeta]

The residue was just gunk from the old caps themselves.  It looks just like the corrosion that batteries sometime leave on the metal contact points of anything that had batteries sit ideal in them for years. Greenish dried up battery acid is the best way I can describe it. 

Well there might be green stuff from the copper tracings reacting from the leakage, but the stuff in capacitors isn't anything like battery acid, so you don't have to worry. If it were batter acid, that could be a problem, but the stuff in a capacitor is just a dielectric, or sometimes oil to keep the things cool.

[Platinumfungi]

Sounds good guys. Thanks for the replies.