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Topic: nicad battery dammage  (Read 9068 times)

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Offline zapdbf

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nicad battery dammage
« on: October 03, 2011, 12:27:53 PM »
I am not a chemist, I am an electronic technician. As a hobby and side job I repair pinball machines.  Battery acid damage is the scourge of this hobby.   NiCad battery’s can (and usually do) leak fluid onto the pc board. This will corrode the copper traces and the Solder joints (40%tin/ 60% lead) the copper corrosion I can handle, it’s the solder corrosion that is a mess to work with.  The solder will turn into a hard caked brown gray powder that is very difficult to remove.
To stop the corrosion I am using vinegar in water – is this a good way to stop the progress of the corrosion ?
Also is there some way that I can dissolve the caked brown gray power that has been created from the battery fluid reacting with the solder?
If I can get these joints cleaned off better then my next goal is to get the copper solder pads clean enough to accept new solder correctly, even after I get this stuff off after allot of scraping, the copper solder pads still will not accept solder well.

Thanks for any advice you can give me.

Offline Arkcon

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Re: nicad battery dammage
« Reply #1 on: October 03, 2011, 01:17:21 PM »
The electrolyte, the fluid used in a battery, for Ni-cads is sodium hydroxide, and vinegar is ... OK ... for neutralizing the alkaline fluid.  But you have to use not too much, or excess will attack components.  How much is too much is too hard to gauge, so just use a little bit at a time, and rinse with plain water as well as you can.  Using an electronics cleaning is best for cleaning any electronics, its a safer solvent than water -- which is what vinegar, vinegar water and the electrolyte basically are.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline zapdbf

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Re: nicad battery dammage
« Reply #2 on: October 03, 2011, 01:54:43 PM »
Thanks, using water on a pcb can be tricky but i have used the technique for many years other contaminate issues and have had no issues. My bigger question is how to remove the solder that reacted with the sodium hydroxide. Is there a chemical solution that i can try to remove this with? My wish is to find a solvent that would break down the reacted solder so I can remove it easily. - This is the biggest issue i have. It is a real job trying to remove this reacted solder. A hot soldering iron does very little to help it will break it up a little but the residue is terrible to get off.
Again thinks for all your advice, I do appreciate it.

Offline zapdbf

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Re: nicad battery dammage
« Reply #3 on: October 03, 2011, 02:15:21 PM »
is the product of lead and sodim hydroxide, lead hydroxide ?
If so this is the stuff i am dealing with.

Offline billnotgatez

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Re: nicad battery dammage
« Reply #4 on: October 03, 2011, 03:09:42 PM »
In the original solder, what is in the solder other than lead.

Is it lead and tin and flux.


Offline Arkcon

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Re: nicad battery dammage
« Reply #5 on: October 03, 2011, 05:40:36 PM »
It is possible that lead and tin can react with the potassium hydroxide in spilled electrolyte to form lead and tin hydroxide.  If there's just a small amount of spill, it may form lead and tin oxide as well, or instead, or with a reaction with the air afterward, as the chemistry of lead and tin is a little bit more complex than for other metals.  At any rate, yes, the corroded solder traces can be a problem for solder adhesion when trying to repair.  Try to scrape, as carefully as possible, the oxide off.  Try to use swabs of vinegar, or other acid cleaning agents designed for solder joint cleaning, like an acid flux, to get the breaks clean before re-soldering.  You appear to be looking for some sort of reagent to dunk the board in and get 100% dexodized solder traces with 0% damage to good solder and other components.  You will not succeed in that search.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline zapdbf

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Re: nicad battery dammage
« Reply #6 on: October 03, 2011, 07:15:57 PM »
The damage is over a long period of time, when i get these boards they have been exposed to the electrolyte for years. Some of the joints are so corroded that the solder is more like a dry granular substance. Capillary action under the solder mask causes the electrolyte to travel all over the board eating the copper traces then the joints when it comes to one. The problem with scraping is that it takes a very long time and time is money as they say. I am trying to make it affordable to repair these boards. and save these old pinball machines from the junk yard. Regular flux causes a gray substance to bubble up and actually makes it a very sticky mess. Worse then trying to scrape it dry. I was hoping for maybe an acid solution that would break it down, as far as the components go they usually are damaged too severely to salvage the area affected is striped of the components in that area once i can get them off, and new components are soldered back in. It is a tedious and time consuming process if i could get the old solder off quicker the process could be cut in half. 

Although the suggestion of using acid flux, i have not attempted to use this, i may and see how this works.

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