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31654Re: Rescuing a circuit board from leaking batteries

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  • s100doctor
    Jul 17, 2013
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      --- In midatlanticretro@yahoogroups.com, Matt Patoray <mspproductions@...> wrote:
      > I am working on an AT&T 55C terminal, the main mother board has a NiCd battery on it that of course leaked... Are there any good methods for removing the nastiness?

      Some of the discussion seems to center on whether the battery was NiCd and the toxic consequences of that. It may or may not be NiCd, it may be some other material, unless you can clearly identify the brand and model of battery. Batteries in general are not excessively toxic; use "rubber" gloves if you are concerned while removing the debris, and put the remains in a plastic bag and turn them over to a recycling facility. YOu can find specific disposal directions for specific types of batteries.

      The general problem with decayed batteries is that the active contents will corrode copper traces and components. Also, removing the debris from the board will also damage components. The most benign cleaner is soap and water, and a soft (they have grades of soft and medium and firm) NEW toothbrush, used with care. After that, there are solvent-based cleaners or dilluted solvents. People have their favorites, I don't think any of them will react awfully to batteries contents of any sort.

      Once the bulk of debris is removed, you can look at the board and see the damage. Look VERY closely, as you may find corroded solder connections or corroded pins on surface-mounted chips, and damage some distance from the battery. Copper oxides are of course, green or blue-green. Remote damage is because years of small currents from the battery ALSO corrode copper and therefore damage components. It's a VERY VERY good idea to remove ANY battery from any computer in storage - period.

      Computers of the 1970's have large traces and most will survive a lot of corrosion and traces can be repaired. Post-1980's computers with surface-mount chips and tiny traces and multilayer boards, often will NOT. 68K Apple Macs are a good example of the latter, with their PRAM batteries creating all kinds of damage after decades on-board.


      Herb Johnson
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