Use of HCL to dissolve severe corrosion from NiCad or Alkaline Batteries or oxidation

[Lyle Bickley]

In response to an offlist question, here's a bit more info on HCL use:

1. I've only been able to buy gallon sized containers of the 30% HCL (Muriatic 
Acid). That is very unwieldily to handle. A polyethelene containter with a 
small "spout" (available at drugstores) is an easy solution. Just be careful 
when transferring the acid from the gallon container to the poly container - 
use a poly funnel - HCL is "nasty" stuff.

2. Use as little acid as possible on a board/module/motherboard. Before 
applying the acid I look over the board - and discover the corroded/oxidized 
components and apply the acid directly to the components. The acid will flow 
to other, non-oxidized components, but it won't hurt them. A toothbrush can 
be used to scrub stubborn corrosion - but I've found it is rarely needed.

3. After applying the acid, rinse it off as soon as the "fizzling" stops. Use 
plenty of cold water to eliminate all traces of the acid. Then use a final 
rinse of distilled water.

4. I avoid putting acid on adjustable, semi-sealed components, such as 
potentiometers, variable capacitors, enclosed switches, etc. If they are 
badly corroded - replace them.

5. I use a hair dryer set at medium-heat/high-speed to dry the board and under 
chips, etc. Drying will also eliminate any traces of residual acid that may 
have been left behind. (HCL turns to a gas when it "drys out").

Cheers,
Lyle
-- 
Lyle Bickley
Bickley Consulting West Inc.
Mountain View, CA
http://bickleywest.com

"Black holes are where God is dividing by zero"