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Anyone have experience cleaning Rust off of a PCB?

twistedsymphony

twistedsymphony

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So I recently picked up a Kaneko Blazeon, the board works fine but bizarrely has rust on a number of pins. This board doesn't have a battery nor is this related at all to leaking caps. it looks like legit iron rust.

IMG_20210514_181944354.jpgIMG_20210514_181916624.jpg
some additional photos: https://photos.app.goo.gl/uhNsT5FpcDgtjxVh9
if it looks wet that's because I've gone over it with some DeOxit.. which seems to have done nothing at all to help.

A handful of pins seem to have rusted through to the top side. too.

I'm a bit at a loss for what to do about it. out of the hundreds of boards I've bought over the years I've never seen a board rust like this I've seen suggestions online for using baking soda or vinegar. but I'm hesitant to just start mixing chemicals on this thing.

the PCB is pretty mint otherwise and like I said it currently works fine, but I'd like to make sure it stays working for the foreseeable future.

anyone dealt with this successfully before? how did you do it?
 
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Tiny bit of diet coke and an old toothbrush? Give it a scrub and then rinse well with purified water and leave to dry in a warm location for a good long while before powering up!
 
I’ve had very good experience removing rust using Evaporust. That being said, I have not tried it on PCBs. It’s very safe to handle so it’s worth a try.

If you have a junk board, you can test on that and see how that goes. I would soak a towel in Evaporust and lay over rusted spots then put everything in a bag to reduce evaporation. I have no idea if its safe on solder mask or plastics or anything non-metal, frankly, so proceed with caution.
 
If it works, you may want to reflow given how rust probably created weak joints.
 
a fiberglass pen with isopropyl was the very first thing I tried... didn't do anything :-/
 
I've seen this before. I think it happens mostly on pins that get broken (common on resistor arrays) or pins that are cut after soldering the offending IC. Since the cut is not protected by solder, it will eventually rust.
To fix it I've found that resoldering the pins with strong flux (SW21 and RMA223 seem to work well) will clear the oxide quite effectively.
Pro tip: ventilation is a must if you are sensitive to flux fumes.
Bonus: your sinuses will get very clean too!
 
I had a CPS2 A-board that took a Coke spill right onto the JAMMA harness. Was left there for years. Traces on the edge connector were green. Used oxallic acid that I bought to get rid of hard water stains on my shower doors. Got it right off, rather easily too. Kept it localized by adding water to the powder to make paste and applied it with a toothbrush. A-board is good as new now.
 
I had to clean a badly rusted Total Vice pcb I got for cheap as non-working. PCB had rust dust and the metal cage was rusted.

For the metal cage I just used white vinegar and a brush. Vinegar should stop the rusting. Cleaned with IPA. Came out nicely.

For the PCB, considering rust dust is conductive, I thoroughly cleaned it with IPA and a combo of toothbrushes/q-tips/make up removal pads. I really drenched the pcb and then let it sit for a day just to be safe. Powered right up.

So I like the vinegar + brush then IPA clean method myself
 
so far:

soaked for hours in ipa then brushed = no effect
soaked for hours in deoxit then brushed = very minor improvement
covered liquid flux then heated then flushed with ipa = minor improvement
covered in white vinegar for a few min then brushed = very minor improvement.

I think next I'll try soaking in white vinegar for hours, but I want to test out in a junk PCB first.

I'm also waiting on delivery of the specific flux mentioned by @ic3b4ll so hopefully that will work better than the stuff I have on hand.
 
I also had that issue with one PCB i got from ebay and like soneone else said i used evaporust. the way i did it was by cutting a paper towel to about the size that I needed to work soaking it in evaporush and placeing it on the affected area for 24 hours. Then cleaning it with water followed by alcohol and pencil eraser after. then i used the hakko to remove the old solder and resolder the joins.

The rust was not affecting the PCB but it was affecting my mental health.
 
twistedsymphony said:
so far:

soaked for hours in ipa then brushed = no effect
soaked for hours in deoxit then brushed = very minor improvement
covered liquid flux then heated then flushed with ipa = minor improvement
covered in white vinegar for a few min then brushed = very minor improvement.

I think next I'll try soaking in white vinegar for hours, but I want to test out in a junk PCB first.

I'm also waiting on delivery of the specific flux mentioned by @ic3b4ll so hopefully that will work better than the stuff I have on hand.
Click to expand...

Sorry for necrobumping this topic but I also have a PCB with oxide (rust) in some of their components (like what @ic3b4ll said, resistor arrays are the most affected compontents) that I want to be cleaned.

This kind of rust, like the one @twistedsymphony posted in his PCB, is produced by atmospheric oxidation when metals and other parts are in contact with moisture or water for a long period of time, but not for a cap or battery leaking.

I plan to replace all of those affected resistor arrays and maybe one or two srams with rust in their legs, but I also need to remove similar rust spots in components and solder side of the PCB, similar of ones of that Blazeon from @twistedsymphony

In the end, what was the better method for cleaning that in your case?
 
I was not able to find a solution that worked.
twistedsymphony said:
soaked for hours in ipa then brushed = no effect
soaked for hours in deoxit then brushed = very minor improvement
covered liquid flux then heated then flushed with ipa = minor improvement
covered in white vinegar for a few min then brushed = very minor improvement.

I think next I'll try soaking in white vinegar for hours, but I want to test out in a junk PCB first.

I'm also waiting on delivery of the specific flux mentioned by @ic3b4ll so hopefully that will work better than the stuff I have on hand.
Click to expand...
soaking in white vinegar for a long periord = very minor improvement (no different than soaking for a few min)
the Flux recommended by ic3b4ll = minor improvement (no better than the flux I had tried before)
I did also try applying a few drops of evaporust to the effected areas and let it soak for 24 hours = no effect (I would suspect it needs to be submerged to really take effect)

And that's about where I left off :-/
Short of soaking the whole PCB in evaporust I'm out of ideas.
 
the tetris bootleg I need it for is not worth 40$ ... so in the garbage it goes.
 
@twistedsymphony sorry it didn't work... Did you try the SW21 or the RMA223? The former is a lot more active than the latter.

@Nebula I think the results will depend on how much rust there is and whether or not the solder mask absorbed it.

Oxides aren't generally conductive, so if you can live with the discoloration in the solder mask it should be fine.
 
I actually tried both and didn't get much of a difference between them.

no harm though, one can never have too much flux :P
 
ItsBobDudes said:
I have used Loctite Naval Jelly on heavily rusted candy cab control panels with great success. If you want to give it a go on a junk PCB I don't mind sending you some.
Click to expand...
This is what I was going to recommend trying. I've never tried it on a pcb either, but it worked great on rusty steel parts in the past.

Naval Jelly is phosphoric acid and converts the rust to a white powder
 
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