Blue Battery Acid Corrosion on Circuitry

[AquaSentinel]

Hi

n00b here.

I opened this 20 year old toy up. Lots of battery acid. There’s blue corrosion. Cleaned up the terminal as best I could. Thought contact would work. Not working. Looks like the blue corrosion(?) has advanced to circuitry. Can see it through the side on the back of the board. I can’t access this side because the battery terminal was soldered on the other side after insertion with plastic barrier between the 2 pieces. Can see the blue has made it through to the front side if you look carefully.

Wondering if it’s possible to dunk this thing in some sort of chemical that will remove the blue corrosion & not damage the rest. You don’t know what you don’t know.

Also does blue corrosion mean something. I’ve seen plenty that isn’t blue.
Many thanx.

[Haenk]

Dipping it will certainly destroy something - like the motor.
Probably best to disassemble it, then mechanically clean the PCB and everything that looks contaminated, some vinegar might help; rinse with destilled water.
Unfortunately, if you don't remove it, it will creep and destroy more and more of that wonderful piece.

[AquaSentinel]

Wow!

I didn’t know it would continue to deteriorate.

I can’t clean it because it was soldered together around the plastic & can’t be removed. So I can’t get to the damaged side.

[Kim Christensen]

The blue corrosion is alkaline, so you'd neutralize it with a mild acid like vinegar. It'll bubble when you brush some vinegar on it.
Best to disassemble and clean. Those tabs can be desoldered with great care and the right equipment.
Another option would be to remove the motor + switch, and then give with whole thing a vinegar bath scrub, fully rinse with clean water, and then fully dry it out without melting the plastic. Is there any sort of speaker for the R2D2 beeps? If so, that should be removed/protected from washing also.

[AquaSentinel]

It has a remote that contains the speaker.

Has the blue “corrosion” possibly damaged the piece permanently? Or does it just stop the electrical flow? I’m wondering scientifically what’s going on here.

[AquaSentinel]

For those interested here’s a working example:
https://youtu.be/kJjc68q9HkU

[Kim Christensen]

Alkalines will erode metals. So eventually it'll cause broken connections once it completely eats through the wire lead and any other metals. It'll also be conductive and disrupt the circuitry.
What you could try is to carefully clean off the battery contacts with vinegar and water rinse without letting it wick down inside. Cotton swab method. Then briefly try a fresh battery to see if it still functions. It seems like it takes an odd battery size/type.

[AquaSentinel]

I’ve already cleaned the terminals as best I can with vinegar. I think the problem is that it’s spread to the back of the circuit board. Can’t access it to see well or take a photo but it’s there.

Will the alkaline continue to spread without a battery source? Or will it just destroy what it’s already in contact with?

It takes AG13/LR44 which is the more common button cell for kids toys. Can’t remember if it was 2 or 3.

Thanks for all the advice Kim & Haenk!

[Kim Christensen]

It might spread a bit more in a higher humidity environment, but nowhere near as much if the old batteries were still in there leaking.
You definitely want to clean the PCB if it's migrated to the back side. Looks like I can see it coming through the holes in the PCB. That'll destroy it, if it hasn't already:

[BlownUpCapacitor]

I think putting vinegar on the PCB is the best option to neutralize the alkaline and then follow it up with a wash with distilled water. The chemical reaction between the acid and base will turn it into soluble salts. Let it dry under a fan for a couple hours then test.

Do the same with the other stuff like battery contacts to remove it all. Don't expose it to the plastic as the plastic may deteriorate.

Do only the PCB and the contacts. Mechanical parts may suffer damage.

This is how I fixed one of my multimeters with duraleak juice everywhere.