On 02/10/2014 22:40, Jon Elson wrote:
Phil Allison wrote:

Nutcase Kook :


Only military grade ICs are specced to hermetic sealed packages.


** Horse manure.


For all

else, water is likely to migrate to the die with some probability

greater than zero, only needs going along one pin of one IC.



** Shame how nearly all PCBs are washed ( ie defluxed) in hot water these
days.

Wot a bull****ting fool you are.
For new components, I agree with you. For boards that have run hot
for a long time, many power/thermal cycles, exposure to possibly
hideously contaminated air, I am not sure I agree. I think that
under such conditions, the sealing of the package definitely may
degrade. The chips themselves are passivated way better than in
the early days, too, and that helps.

On the other hand, getting things cleaned up well, and then make
sure to properly dry them before powering on, it should be OK.
Once the chips get warmed back up, the water will be driven out.
Gear that runs stone cold should definitely be dried carefully
(ie. some heat applied).

Jon


Once the thermal cycling has broken the seal somewhere, then the gap is
of ideal capillary-action dimension to suck up any water