I'm having some issues with electronics since I moved to a new weather., Here humidity goes up to 80%. Last thing is that I found some corrosion (like green and white stuff) over the tiny pins of the atmega16u2 of my Arduino Mega. I'm guessing this may be related to my board happening to be unplugged and plugged suddenly, this because I understand this chip handles USB. I tried applying some solvent (sorry if its a mistake!!) and cleaning but is still there. What could I do? I would like to also clean like the whole board... should it be enough by using an electronic cleaner?
That is oxidation and you can not remove all of it with solvents, because the oxides are not soluble in such liquids. But a gentle scrub with a PCB safe cleaner will remove some of it, just from the friction of the brush.
This is why a conformal coating is used on electronics intended for harsh environments - it should
be possible to apply conformal coating yourself if corrosion is an issue. It would be wise to clean
with distilled water and IPA first to remove any traces of salts (which accelerate corrosion greatly).
Handling a PCB is one way to put salts on the surface, note.
Corrosion may be due to simple chemical action, or if there is a moisture path across the PCB surface
you can get electrolysis if the circuit is powered up. How its plugged in is not relevant, whether its
plugged in is.
I did not know what conformal coating was, thanks a lot I have an idea of it now.
I boutght a CRC cleaner. I tried my best to clean it up. It improved a lot but there are still small signals of corrosion.
I've ran the program in the board and it works pretty well.
It looks to me to be a result of flux on the board coupled with moisture. Just a note, there is no "No Clean" solder. There are solders whose flux is not very active and in many cases can be left behind. But under the wrong conditions No Clean solder flux can corrode.
I clean my boards with 91% alcohol and a small brush (like a stiff toothbrush). Once you brush the area with alcohol use a paper towel to absorb the liquid on the board so any corrosion particles don't just stay on the board when the alcohol dries. After blotting the area I use an air compressor to blow off any under the chip. I don't recommend this to others as folks will tell me its not ESD safe, yet I've been doing it for years.
I've also cleaned boards in hot water and a mild detergent. Then rinse with hot water. In a production setting one would use deionized water but my tap water seems OK. If one wanted to be more correct you could make the final rinse in distilled water from any grocery store.
JohnRob:
I've also cleaned boards in hot water and a mild detergent. Then rinse with hot water. In a production setting one would use deionized water but my tap water seems OK. If one wanted to be more correct you could make the final rinse in distilled water from any grocery store.
I have done a similar type of clean, one board so bad it was a all or nothing, cleaned in water/mild bleach solution.
PCB was a CPU board, 8085 type, lots of 40pin wide DIL ICs soldered in, PCB was knackered (mouse nests), but situation dictated a clean had to be tried. It worked, a liberal spray with WD40, but a new PCB assembly was fitted a couple of days later.
DIL legs on ICs were a "little" thinner that the originals.
Tom..
JohnRob:
It looks to me to be a result of flux on the board coupled with moisture. Just a note, there is no "No Clean" solder. There are solders whose flux is not very active and in many cases can be left behind. But under the wrong conditions No Clean solder flux can corrode.
I clean my boards with 91% alcohol and a small brush (like a stiff toothbrush). Once you brush the area with alcohol use a paper towel to absorb the liquid on the board so any corrosion particles don't just stay on the board when the alcohol dries. After blotting the area I use an air compressor to blow off any under the chip. I don't recommend this to others as folks will tell me its not ESD safe, yet I've been doing it for years.
I've also cleaned boards in hot water and a mild detergent. Then rinse with hot water. In a production setting one would use deionized water but my tap water seems OK. If one wanted to be more correct you could make the final rinse in distilled water from any grocery store.
I agree 100% with the stuff on the board being left from improper cleaning at the factory! No clean solder flux is based on the flux in the solder being heated to such a temperature that it decomposes into inactive chemicals. Really hard to accomplish in reality because of the soldering person is trying to use minimum heat do get the job done, not deactivate the flux.
Paul
I didn't think of it when I posted my cleaning procedure(s) but on leaking batteries I've used windex with ammonia (being a base solution) with success.
A key point is to be sure the board is dry when you are finished. Even if you have to let is sit on a radiator overnight.
JohnRob:
I didn't think of it when I posted my cleaning procedure(s) but on leaking batteries I've used windex with ammonia (being a base solution) with success.
A key point is to be sure the board is dry when you are finished. Even if you have to let is sit on a radiator overnight.
Before drying, use compressed air to remove water and crap from under all components. Leftover crap is just as bas a visible crap on a circuit board.
Paul
