NiCad battery corrosion and cleanup

I have an older piece of an expensive equipment whose NiCad memory battery sprang a leak.
I have green solder bridges in a few places and little green microsopic bunnies everywhere.
I used rubbing alcohol to no avail. Using hydrogen peroxide seems to work, The bubbles ( hydrogen or oxygen?) loosens the bunnies and using canned air blows them away.
I am planning to soak the whole board in plain water afterwards and dry it up, maybe even use WD40 to make sure it does not have any water left over.
Should I be concerned about long time effect of my home remedy, say five years?
I would also like to know what is this stuff anyway - chemically - just out of curiosity.
It looks like using AAA style NiCad battery soldered to the circuit board is not very good idea.
However, this radio service analyzer must be more than 25 years old.
Thanks for reading
73
Vaclav
AA7EJ

[WA9SVD]

Quote[/b] (aa7ej5 @ July 05 2007,09:43)]I have an older piece of an expensive equipment whose NiCad memory battery sprang a leak.
I have green solder bridges in a few places and little green microsopic bunnies everywhere.
I used rubbing alcohol to no avail. Using hydrogen peroxide seems to work, The bubbles ( hydrogen or oxygen?) loosens the bunnies and using canned air blows them away.
I am planning to soak the whole board in plain water afterwards and dry it up, maybe even use WD40 to make sure it does not have any water left over.
Should I be concerned about long time effect of my home remedy, say five years?
I would also like to know what is this stuff anyway - chemically - just out of curiosity.
It looks like using AAA style NiCad battery soldered to the circuit board is not very good idea.
However, this radio service analyzer must be more than 25 years old.
Thanks for reading
73
Vaclav
AA7EJ

In short, the "blue stuff" is Copper sulfate, CuSO4 (Sorry, subscripts don't work in Windoze.) And "green bunnies" are other Copper oxidation products; (sulfides, nitrates, ,etc.) and ALL are signs of corrosion.

It comes from a chemical reaction between the corrosive components in the battery and the copper PC board traces. Unfortunately, it DOES indicate corrosion and damage to the PC board traces, as they have been (at least) partially eaten away; in severe cases, an entire trace can be eaten through, rendering a piece of equipment unusable.
As you have unfortunately discovered, not all of these
corrosion products are easily (quickly) soluble in water. (Truly a bummer. )

If the application of H2O2 (peroxide, again, no subscripts allowed) seems to dissolve the corrosion, than that IS to your benefit. Remove ALL the corrosion, and I do mean ALL, not just that which is easily visible, from ALL parts of the circuit board.
Then, and only then, apply the "water torture" treatment. (Break down and buy a gallon of "DISTILLED" water at the local grocery; accept NO substitute. It WILL be as pure as possible, and not contain ANY minerals at all. Any so-called "pure" water that isn't distilled is not as good.)

Depending upon the components on the board, you can either:

1. Swab the affected areas with clean water REPEATEDLY, to insure you have removes all traces of the corrosion AND any agent used in the cleanup.

2. FLUSH (in addition to step 1 above) the entire board with the distilled water.

2a. If the components on the board can withstand the treatment (resistors, molded or sealed ceramic caps, etc.) soak the entire board in the distilled water for a few minutes to an hour, to allow as much corrosion and clean-up gunk to dissolve.

3. Rinse with distilled water, both sides.

4. Air/sun dry after (carefully) shaking excess water from the board. If you CAN set a board out in the sun for a few hours, it WILL speed drying time.
5. Allow sufficient drying time. Different PC board materials, and even some components may take more time than expected to "dry." A full day, especially a full day in the sun isn't excessive, even if not necessary. Just use judgement here.
6. Inspect, CAREFULLY, the board, particularly the areas most affected by the corrosion. if there are traces that have been destroyed because of corrosion, they will have to be repaired. If they are small thin traces (the ones most susceptible to damage) they canoften be repaired with a small tipped, low wattage solder iron and a strand of wire from a piece of 20 AWG or so stranded wire. If a WIDE (current handling) circuit board trace has been damaged, then an external jumper may be required.
6a Spraying a board with WD-40 has its proponents, but WD-40 really isn't for widspread use on a PC board, and COULD have a delitrious effect on some components, since it IS a petroleum based (read: solvent) lubricant. Use sparingly at best as it DOES leave a residue.
7. Install a new battery as needed, and allow time to charge.
8. Make mental note to check every few years, along with other electronic gear and gadgets (including computer motherboards) in the shack and home that may have internal batteries so you don't have to perform the same repairs to other items.
9. Also be aware that some batteries at or near the end of life may start to leak long before they no longer provide power or a usable voltage. Just because an old battery seems to be providing it's purpose for backup does NOT mean it isn't starting to leak. It's better and easier to check than have to repair.
9. Other items to check are:
TV, cable, and other home entertainment electronics that use a remote
garage door openers
auto alarm key chains
alarm clocks with battery backup

The list could be endless.

And don't forget to replace the "smoke detector" batteries at least once a year. THAT is one place you don't want to wait for the batteries to fail before you replace them.

Finally, dispose of used batteries responsibly. Save them up if need be, and take them to a recycler, even if they are the "nickle and dime" type of flashlight battery; many areas DO have laws requiring recycling of all batteries, not just the NiCd cells, which ARE the most hazardous to the environment, after lead-acid batteries.

[VK2AKG]

I think you will find this link informative:
http://www.rskey.org/calccorr.htm

Good luck! (you will need it), Frank

[WA9SVD]

[quote=VK2AKG,July 05 2007,19:53]I think you will find this link informative:
http://www.rskey.org/calccorr.htm

Good luck! (you will need it), Frank




The above link states:

"what about the blue or green stuff? That stuff, believe it or not, has almost nothing to do with batteries; it has everything to do with the presence of voltage (whether from a battery or another source) in a damp environment (that's my theory anyway.)"


Well, that's the "theory" of the person in your reference. But it's just not accurate. Voltage alone will not produce the corrosion in the "blue or green" gunk. It wouldn't appear in a piece of equipment powered solely from line voltage, even at "eternal" trickle levels. And it doesn't occur in equipment where batteries are kept properly charged or replaced when failing. It IS caused by leakage of batteries, and or high humidity experienced by the equipment in question. Humidity alone CAN cause such corrosion IF corrosive solder flux was not completely removed, regardless if any battery or voltage is present in a circuit.

[VK2AKG]

Larry, the quote you attribute to me not only includes things which I did not say but is obviously much larger than my original posting.

Are you able to do the same for my bank account?

[WA9SVD]

Quote[/b] (VK2AKG @ July 06 2007,07:05)]Larry, the quote you attribute to me not only includes things which I did not say but is obviously much larger than my original posting.

Are you able to do the same for my bank account?

Only after I do it to my own account!

Sorry if I made it appear those were all your words. It was a sloppy job of cut and paste.

To be specific, the words are from the article you indicated. (I'll try to fix it.)

[VK2AKG]

Thanks Larry.

aa7ej5 Notwithstanding the snippet which has been quoted above, I still believe you will find something of value in the following the link I provided.

Good Luck,

Frank

Operation sucessfull, but patient died!
Well, I did clean the green stuff as far as I am concerned.
Buttoned it up an it run for about half an hour.
Then it clicked and all I am getting now is all zeros on the display and ERROR.
One of the ribbon cables did not get cleaned up and in the process of uplugging it it broke.
I need to take the front pannel off and start over.
Anybody wants Cushman Radio analyzer build in 1982?
Needs work!

[WA9SVD]

Just to add:

The corrosion is usually a mixture of copper compounds, some green, some blue. (Copper hydroxide and others are green; others, such as Copper sulphate, are usually blue) that result from the leakage of various types of batteries, rechargeable or not.
But again, batteries can start to leak BEFORE they no longer provide voltage, so it's better to check before batteries of ANY type are completely dead.

[K8ERV]

I hear the stuff is green cause red was already taken-- (no, K8ERV did NOT say that)!

Tom K8ERV Montrose Co.