In a previous life doing contract manufacturing, we had a switch that
was rated by it's manufacturer as being washable... Investigation
showed that not to be quite true. But of course it was established with
the customer (and designer) as a good part, so we had to make it work.
We ended up putting finger cots on the switches before putting them
through the cleaner. The switch had an o-ring to seal it, but under
water pressure it wasn't quite working.
Not the best fix, but the obvious alternative was to install it last,
using "no-clean" flux. Yech!
What kind of defects? The switch would short out - we'd find it during
test. Because it was sealed anything that got in there tended to stay
in there for a while.
regards,
- Graham
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ken Bloomquist
Sent: Friday, April 18, 2008 1:34 PM
To: [log in to unmask]
Subject: Re: [TN] Defects related to water wash
Hi Carl,
Sorry to have sidetracked your original email subject.
If you have components that are sensitive to moisture entrapment then
they must be sealed during water wash. If you get water into say a
switch then a number of bad things can begin to happen. Some that come
to mind are corrosion to internal metal parts, dendrites growing if
contaminants got into the switch along with the water, a sticky switch
again if more than just plain water got in there and the worst thing is
that most of the defects will be latent only causing a problem when your
customer needs your product at a most important moment!
I'm sure others will chime in with more reasons but the manufacturers of
components warn against washing particular parts for a reason, don't do
it unless you seal them really good!
KennyB
-----Original Message-----
From: Ray, Carl (GE EntSol, Intelligent Platforms)
[mailto:[log in to unmask]]
Sent: Friday, April 18, 2008 7:59 AM
To: [log in to unmask]
Subject: Re: [TN] Defects related to water wash
My initial question was related to functional damage to components due
to the exposure to the washing processes. Not any types of mechanical
damage. Example - BIT Switches have tape to protect the component from
the wash process. If the tape was removed or if a part was not designed
to withstand a washing process what types of related defect could be
expected, short and long term?
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