Removing oxidation from plated through holes

[gkmaia]

Hi,

I got some hard encrusted blue oxidation on most of the plated through holes of my Game Gear PCB.

I've been reading about ultrasonic cleaning, ammonia, baking powder. Also read that oxidation on copper/nickel is also a good thing as it builds a protective oxide layer.

So I don't want to be poking into those holes and then damaging the plating.

Any ideas on how to clean it NON-mechanical? With chemicals?

OR

Should I just leave it as it is?

[PKTKS]

Your photo may be not the best shot.

But as far as I can see IT IS **NOT** even close "BAD"

But the corrosive rust  already started and there is no way back.

This case seems simple JUST BRUSH THE RUST W/ IPA (ISOPROPANOL)

Mild brush lot of IPA brush all crappy rust with care...
Dry with a lint free paper or just air.

If you want to protect the corroded parts try PCB varnish in small amounts
spot based

Paul

[shakalnokturn]

Of course getting rid of the cause of oxidation would be a good thing.
Those SMD electrolytic capacitors appear to be the original parts, they have spewed a good amount of their electrolyte.

[gkmaia]

Of course getting rid of the cause of oxidation would be a good thing.
Those SMD electrolytic capacitors appear to be the original parts, they have spewed a good amount of their electrolyte.

Yes, they did. I got to remove them but before I want to decide how far to go with the corrosion issue. May not be worth.

[gkmaia]

Your photo may be not the best shot.

But as far as I can see IT IS **NOT** even close "BAD"

But the corrosive rust  already started and there is no way back.

This case seems simple JUST BRUSH THE RUST W/ IPA (ISOPROPANOL)

Mild brush lot of IPA brush all crappy rust with care...
Dry with a lint free paper or just air.

If you want to protect the corroded parts try PCB varnish in small amounts
spot based

Paul

Nice, Paul! Thanks! Ive done lots of IPA and brush already but the rust inside the holes are just impossible to remove. Can't poke them as they are hard as a rock inside those holes.

What about pcb green mask those holes and isolate them from enviroment?

[PKTKS]

Nice, Paul! Thanks! Ive done lots of IPA and brush already but the rust inside the holes are just impossible to remove. Can't poke them as they are hard as a rock inside those holes.

What about pcb green mask those holes and isolate them from enviroment?

yep that "absorbed"  rust will not just be wiped out that easy.

From my trial and error procedures removing and replacing rusted parts...

The only method that will remove the rust is to remove the solder joints itself.

And that will vary cf. the amount of rust and oxidation of the joint

Mild ones you may just "wick" out with a good "RA" flux

The bad ones... I use a very aggressive flux ... really nasty stuff - BUT WORKS
Requires a lot of care to apply and ASAP to clean that   

Really magical stuff when dealing with corroded joints that refuse to melt properly
and continue in blobs and residues

The stuff I use melts the oxides and I can just wick or suck all very easy.

This:
http://www.soldabest.com.br/produtos_pasta_soldar.htm

or the orange pot from this guys.. both are similar stuff
http://cobix.com.br/produtos/produtos

Aggressive stuff. Corrosive and residual.. but works removing all oxides fast and clean

Have no better alternative than this to do a SAFE (preserve PCB from damage) and clean job

They are soluble in IPA. Cleaning is not that bad..
Paul

[ebastler]

If it's blue, why would it be "rust"?
Electrolytes or salts, maybe?

Have you tried cleaning/brushing with water? If there are no sensitive mechanical parts on the board (switches etc.), immerse it in soapy water and brush gently, then rinse off with distilled water and dry in a warm place.

If the residue is stubborn and you are serious (reckless?  ), just put the whole board in a dishwasher.

[Clint_dk]

Try give a shot of deoxit contact cleaner through the holes.

[PKTKS]

If it's blue, why would it be "rust"?
Electrolytes or salts, maybe?

Have you tried cleaning/brushing with water? If there are no sensitive mechanical parts on the board (switches etc.), immerse it in soapy water and brush gently, then rinse off with distilled water and dry in a warm place.

If the residue is stubborn and you are serious (reckless?  ), just put the whole board in a dishwasher.

My interest in this topic is very specific.

I have a board that is really hard to clean than that.

VIAS are filled with that sort of "blue/white" oxidation...
and  even scrapping IPA over it will not clean underneath.

This is not the first time I have heard some ideas of "washing" (w/water)..
Sounds really weird.  If IPA will not do it right ... how water should do it?

Best case scenario so far is Ultrasonic bath in IPA. Or else.. other solution...

Ideas welcome

Board attached

Regards
Paul

[ebastler]

Sounds really weird.  If IPA will not do it right ... how water should do it?

While both water and IPA are polar solvents, many molecules are dissolved in water much more easily than in IPA or other alcohols.

Have you ever tried to dissolve salt in alcohol? Doesn't work all that well...
https://www.reddit.com/r/askscience/comments/19bwki/why_doesnt_salt_dissolve_in_rubbing_alcohol/

[KL27x]

Blue color makes me suspect the board was exposed at some point to a base like say ammonia. Perhaps animal urine. Sorry, I have no suggestion for removing it.

[helius]

Use a strong solution of ammonium thioglycolate (hair perm salt) with .5% benzotriazole. Allow to soak for several minutes to an hour.
This chemical is being sold now in Japan for corrosion removal and is also available in the US for removing rust stains from marble.

[wraper]

This is not the first time I have heard some ideas of "washing" (w/water)..
Sounds really weird.  If IPA will not do it right ... how water should do it?

IPA is among the most useless solvents to clean corrosion. Almost all corrosion that comes off is due to mechanical impact, not IPA. Organic solvents in general are not good for dissolving salts and oxides.

[StuartA]

The various comments about water and IPA are all true, but...Corrosion products are more likely to be soluble in water than in IPA, but IPA is a good wetting agent, so a mixture of say 10% IPA in water provides a good combination. You frequently hear of people talking about using lemon juice to remove corrosion products caused by old batteries, but lemon juice is really citric acid which is acting as a chelating agent, i.e. a chemical that combines with metal ions in a way that makes them very soluble, but wouldn't normally attack metal itself. So, a mix of water, IPA and citric acid (available commonly as a white powder) should make an interesting cocktail, and if you can get access to an ultrasonic bath, that should help nicely.

[daniel444]

copper sulfate is blue in color
a protective oxide layer would not be visible

[StuartA]

Copper sulphate is blue. I thought the folks in Aus would know that. And please don't call up IUPAC  .

[ebastler]

Copper sulphate is blue. I thought the folks in Aus would know that. And please don't call up IUPAC  .

You mean, as in "Sulfate is the spelling recommended by IUPAC, but sulphate is used in British English"? 
https://en.wikipedia.org/wiki/Sulfate

[PKTKS]

Thanks for the helps

The blue green white crap is not cat dog kid or other urine....

Here the air is filled all daylong all year through a very salty
ionic breeze (sea spray) which is impossible to avoid.

Combine this (hot) air  (temps are also high all year) with the fan
inside the electronics  cases  and you have a very good corrosive device

The ionic air spread by the FAN is corrosive by itself.

I see that some kind of these ionic salts will not dilute on IPA
otherwise they will on water at some degree.

BUT. Don't forget to consider that other near by parts will be
affected far most from water than from IPA.

So far scrapping IPA over those corroded parts works fine enough
corrosion does get wet and fluid enough to be removed...

I have heard other combinations of powerful solutions like
https://www.all-spec.com/Catalog/Chemicals-Cleaning-Supplies/Ultrasonic-Cleaners-Accessories/Ultrasonic-Cleaner-Solutions/000-955-516-6768

OR
https://www.ebay.com/itm/Branson-EC-Electronic-Cleaner-Ultrasonic-Cleaner-1-Quart/183639687580?epid=9007302161&hash=item2ac1c7419c:g:ttMAAOSw4RZbIu0p

But they are very price and chemicals import legislation here is just insane...

Anything paste with ammonia  would do the magic trick but inside VIAS
they will also  left conductive residues...

I have wonder a combination of such paste and fast IPA bath..
some vent and warm rest oven to evaporate residues..

Paul

[wraper]

Anything paste with ammonia  would do the magic trick but inside VIAS
they will also  left conductive residues...

If you use any cleaning solutions other than organic solvents, you need to clean with pure water afterwards regardless.

[PKTKS]

If you use any cleaning solutions other than organic solvents, you need to clean with pure water afterwards regardless.

nah  I mean a regular crappy paste I use for corroded solder joints.

The stuff does magic.  Corrosion vanishes ..

Such paste unfortunately is also corrosive and conductive.

After soldering the corroded spot the residues must be cleaned

In regular THT spots there is no problem but VIAS will need special care..

THIS CRAPPY STUFF DOES MAGIC ON CORRODED SPOTS
http://www.soldabest.com.br/produtos_pasta_soldar.htm

but be warned.  It is corrosive and conductive and residue prone.

In simple terms you apply the crappy paste (ammonia based) and heat it up
All corrosion vanishes in a nasty cloud of oxides.. the spot will be left clean with 
some residues to be cleaned.

e.g.  No corrosion left but with the paste residues left
Fortunately these residues are very easily soluble in IPA