Is there a way to remove corrosion off electronic components?

[Refrigerator]

I scored a 3000 piece roll of optocouplers at the flea market, problem is they've been stored in a very damp environment and have corrosion on their legs, which makes it impossible to solder them.
They only cost me 1€, which is not a huge loss, but i mean do i really have to throw them all out? 
So far i've tried vinegar, battery acid, concentrated muriatic acid and caustic oven cleaner and none seem to help, any suggestions?   
I have some copper chloride etching solution so i might give that a try.

[Refrigerator]

As luck would have it, copper chloride etching solution is perfect at removing the corrosion.
After just a few minutes the optocouplers become perfectly solderable 
Case closed 
But just in case post what you know about removing corrosion off components   

PS: in the picture you can just about see a dark cloud around the optocouplers as they soak in the etchant, which is material being removed. So my etchant is not just self-plating copper as it tends to do on stainless steel tweezers, for example.

[Faranight]

What concentration of CuCl2 did you use for etching?

EDIT: Also, you may want to re-tin those pads after etching them because exposed copper (assuming the pads are copper) may oxidize over time when exposed to air. I hear there are some tinning solutions available that may do the job.

[DavidAlfa]

Did copper chloride fully clean the black tin oxide or was it just "good enough"?

About 2 months ago I had to refurb a Tek TG501, everything was badly oxidized, see attached pictures.

Not wanting to take unnecesary risks as lots of parts were unobtanium, I replaced every socket and brushed all the ics by hand.

[strawberry]

like this? desolder all components. scrape off rust layer and dip in acid. some transistors pins corroded off down under glass
VEF elektroakustiskais agregāts
https://boot.ritakafija.lv/forums/index.php?/topic/180444-restauracija-radiotehnika-7111-101-odisej-002-001-sakta/

[DavidAlfa]

omg, was it in a river since WWW2?  Nice job

[Bud]

Often times the bottom of a river is cleaner than "Lab"s of some people on this forum 

[coppercone2]

I duno if thats a good idea, what if the package has small cracks that absorb the solution?

Usually the cleaning bath you use for PCB is not gonna get corrosive materials into the parts even if they leak, so long you bake it out, maybe a bit of soap residue.

If I were to do this, I would dip them precisely while on a clip so they never get submerged.

Rinsing maybe, dipping I would say is risky business, especially for a opto that is designed to isolate HV.

I would do ultrasonic bath with lab soap, then follow up with small abrasives (like fiberglass or brass mini brush) for anything left behind, then clean again.. but not acid. You would be surprised how much oxidation a ultrasonic bath can get rid of with just soap.

I did a acid bath for rusty lead diodes I had once (like evaporust), and they all failed, at only 20V. Soaked em maybe 5 min, rinsed, and baked them at 80C for a long time.. but they failed

[thm_w]

I did a acid bath for rusty lead diodes I had once (like evaporust), and they all failed, at only 20V. Soaked em maybe 5 min, rinsed, and baked them at 80C for a long time.. but they failed

Evaporust is neutral, not acidic, so is safe to use.
Did you test the diodes before soaking?

[coppercone2]

i said like evaporust, this stuff is acidic I think, its the one from the hardware store, maybe metal rescue, it stings, I think its formic acid, never tasted it but if you have a wound it stings like vinegar or something, feels acidic

I did not test the pH or anything, I just assume stings = acid

by test I did a diode test, that looked ok, but in circuit they were poofing on me

[thm_w]

Yeah just warning people that if evaporust is safe to use but alternatives may not be as safe.
Interesting.

[BradC]

Just be aware that Chloride ions are tenacious little buggers and like to stick around. Your post-etch cleaning process needs to be meticulous or you risk ongoing corrosion down the track (both figuratively and literally).

[vk6zgo]

omg, was it in a river since WWW2?  Nice job

It looks a bit like the Uher "reel to reel" tape recorder I once had, that had been through a cyclone.

[tooki]

I would also be worried about etchant seeping into the case along the pins.

I would simply use a fiberglass brush to remove the corrosion mechanically.

[EPAIII]

YES!

If they still work after that bath in etching solution, just how long will that continue to be true. Most IC packages are not hermetically sealed. Gas and liquids can enter and, once inside, would be very difficult to remove.

Mechanical cleaning would be best. Followed quickly by a tinning to prevent further corrosion.

I would also be worried about etchant seeping into the case along the pins.

I would simply use a fiberglass brush to remove the corrosion mechanically.

[Refrigerator]

Just be aware that Chloride ions are tenacious little buggers and like to stick around. Your post-etch cleaning process needs to be meticulous or you risk ongoing corrosion down the track (both figuratively and literally).

Copper chloride is pretty friendly as far as sticking around is concerned.
Unlike ferric chloride it doesn't perma-stain everyting it touches and it washes off very easily.
So far i've not tested the optocouplers, i'm pretty sure they'll be fine based on my experience with copper chloride.
And i don't plan on using them for anything mission critical, just low voltage hobby projects.

[Refrigerator]

What concentration of CuCl2 did you use for etching?

EDIT: Also, you may want to re-tin those pads after etching them because exposed copper (assuming the pads are copper) may oxidize over time when exposed to air. I hear there are some tinning solutions available that may do the job.

I don't know, copper chloride is self-regenerating, meaning it gets more concentraded the more you use it.
This particular solution is close to 10 years old.

[Refrigerator]

Did copper chloride fully clean the black tin oxide or was it just "good enough"?

About 2 months ago I had to refurb a Tek TG501, everything was badly oxidized, see attached pictures.

Not wanting to take unnecesary risks as lots of parts were unobtanium, I replaced every socket and brushed all the ics by hand.

The leads take solder like new.
Although they don't look like bare copper, more like grey-ish brown.
At first i thought they were still corroded because the leads looked dark but they take solder perfectly well.

[Coordonnée_chromatique]

Hello, there are some nichicon FG fine gold caps !
"Rich sound in the bass register and clearer high end"

Did it improve the transparency and details or imaging ? 

[strawberry]

it is FW series cheaper
I buy them in bulk quantity
tested over frequency range and they are ~10% better than good chinese cap . I suspect nichicon longevity could be much better.

[coppercone2]

Did copper chloride fully clean the black tin oxide or was it just "good enough"?

About 2 months ago I had to refurb a Tek TG501, everything was badly oxidized, see attached pictures.

Not wanting to take unnecesary risks as lots of parts were unobtanium, I replaced every socket and brushed all the ics by hand.

The leads take solder like new.
Although they don't look like bare copper, more like grey-ish brown.
At first i thought they were still corroded because the leads looked dark but they take solder perfectly well.

try putting it in the ultrasonic with alnox, I found it makes things shiny

like metal transistors that look old look newer, and unused solder/crimp connectors too (i.e. spare blades on a connector).

A few times I though "holy shit, how the FUCK am I  gonna get all this looking decent" but I am pleasantly surprised after the ultrasonic to only a few patches being bad, which I can hit with neverdull or something. But beware ink disappearing.