GregS wrote:

In article , "Michael A. Terrell" wrote:

"Paul E. Schoen" wrote:

"William Sommerwerck" wrote in message
...
I remember having problems with leakage on a board that
stored voltages in polystyrene capacitors using CMOS
switches and op-amps, but the voltage would bleed off too
quickly to be useful as a "memory". We tried all sorts of
flux removers and it still didn't work well enough. But I had
had an idea that it might be ionic contaminants such as
salt, so I took a board into the mens room and scrubbed
it with hand soap and flushed it with hot water. Then I dried
it with a heat gun, and "voila" it worked like a champ rather
than a chump.

Interesting observation.

Question... Wouldn't distilled water alone flush off ionic contaminants?

Probably. But there may be some sort of oily residue that will be removed by
the detergent. And hot water from the tap is much cheaper. It may be good to
do a final rinse with distilled or deionized water. I have heard that some
people stack their boards in a dishwasher. But my method works for me and is
is very practical for small quantities.


We used a citrus based cleaner in a commercial board washing machine
at Microdyne. It was a modified stainless steel industrial dishwasher
with a separate solvent tank and fresh water wash. Then the boards went
into a board drying oven for 12 to 24 hours. This was for small runs of
boards stuffed and reflow soldered in house.

I noticed citrus based degreasers leave behind oil.
Thats a bad thing when you really want to paint something thinking
it will work. Bad for tape sticking also.

I think I allready mentioned mens room board cleaning.


Mention whatever you want, but it was a NASA approved process. We
built telemetry equipment for the aerospace industry. NASA wouldn't
approve of your method. We built millions of dollars worth of equipment
per year.