[amsat-bb] Elex equip surviving total immersion

Franklin Antonio antonio at qti.qualcomm.com
Mon May 29 22:38:17 UTC 2017

You found the magic method!  

Most people don't realize how LOOOONG it takes for water to evaporate out of all the really tiny spaces under ball grid integrated circuits and whatnot these days.  I have long recommended 24 or 48 hours or even longer at 150F.  Higher temps risk melting plastic parts. 

Opening the gizmo so water vapor can get out is of course also helpful, but most folks don't know how.  If you can't open a gizmo, then cycling temperature between room temp and 150F can also be helpful.  This "pumps" the water vapor out.  It takes a long time to do a cycle, because you have to wait for the innards to really cool, and there are long thermal time constants.   I do it by raising the oven to 150F, then turning it off and letting it cool down over the next couple of hours, then repeat.  I suggest anyone doing this PUT A SIGN ON THE OVEN so nobody accidentally tries to use the oven during this time.

The thing that destroys wet electronics is electrolytic action.  If you can take the battery out, do it instantly.  Otherwise, while it is wet current will flow thru the water bridges between circuits, and deposit conductive compounds formed from the metal ions moved by the current.  Once you have a bunch of conductive junk under chips etc, recovery is very very difficult.  If you can't take the battery out, turn the thing off as soon as possible (which of course in modern electronics doesn't mean really "off", but at least some circuits will be deenergized.)  Then begin the drying process immediately.  Time is your enemy, as every second the battery is in, metal ions are moving.

Impatient people don't leave the phone in the oven long enough, try to turn on and use the still-wet-inside gizmo, thus destroying it.

Did someone take a video of you in the muck?   We might even pay to see that.  

From: AMSAT-BB <amsat-bb-bounces at amsat.org> on behalf of Robert Bruninga <bruninga at usna.edu>
Sent: Monday, May 29, 2017 2:11 PM
To: amsat bb
Subject: [amsat-bb] Elex equip surviving total immersion

Leaning over the edge of a pier, I heard a plunk and as they say, time
slowed down as my brain instantly realized it was my cellphone,.

I jumped in and dug around in the muck (about 3' deep) and probably in
under a minute found it.  Ran to the house. ran fresh water all over it,
dried it and then the same with alcohol.  Then dried it in the toaster oven
(NOT ON, but I'd let it get too hot to touch, then turn it off and stick
the phone in.

That sorta worked.  But the screen was shot.  Next day I took it apart 2
screws and then just unsnap everything.  There is virtually nothing inside
but one circuit board anda  few chips and the chcklet keyboard.  The screen
would not detach.

So I then put the ckt brd  in a 60C (140F) box and left it 24 hours.  Now
it works perfectly!

Just FYI
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